International Journal of Power Electronics (96 papers in press)
Selective Harmonics Elimination for Three-Phase Seven-Level CHB Inverter Using Backtracking Search Algorithm (BSA)
by Sourabh Kundu, Arka Deb Burman, Santu Kumar Giri, Sarbani Mukherjee, Subrata Banerjee
Abstract: This paper introduces backtracking search algorithm (BSA) to solve the nonlinear transcendental equations to obtain triggering angles of a three phase seven-level cascaded H-bridge (CHB) inverter and also eliminates 5th and 7th order harmonics while satisfying the requested fundamental component. A comparative study has been made in terms of execution time, the statistical probability of achieving global minima, and a rank of convergence rate to establish the supremacy of the BSA optimization technique over other recognized methods such as genetic algorithm, bee algorithm, and particle swarm optimization techniques. Simulation and experimental results confirm the effectiveness and accuracy for obtaining precise switching instants that fruitfully satisfy the required output voltage quality.
Keywords: backtracking search algorithm (BSA); bee algorithm (BA); cascaded H-bridge (CHB); genetic algorithm (GA); particle swarm algorithm (PSO); selective harmonic elimination pulse width modulation (SHE-PWM).
A New Reduced Switch Count Three Phase Multilevel Inverter
by GEETHA Ramanujam, Ramaswamy M
Abstract: The paper develops a new multilevel inverter (MLI) topology with a view to reduce the number of power switches in the passage of current to reach each level of the output voltage. The philosophy involves the use of bidirectional switches to avert the flow of circulating current between the two sections of the power circuit. The formulation brings in the use of a new pulse width modulation strategy to eliminate the higher frequency components of the output voltage. It incorporates the phase disposition type of modulating scheme to shape both the voltage and current to a nearly sinusoidal waveform. The total harmonic distortion indexed by smaller values for the output voltage over the traditional firing scheme serves to be the highlight for the MLI in acclaiming its place in the inverter world. The experimental results obtained using a prototype validate the simulated performance and establish the viability of the proposed MLI to serve the diverse needs of the utility world.
Keywords: Multilevel inverter; Total harmonic distortion; Phase disposition; Pulse width modulation.
Optimum Pulse-width modulation strategy for a symmetric cascaded Multilevel Inverter
by Ashraf Yahya, Syed M. Usman Ali
Abstract: This paper investigates for the most suitable PWM strategy for a symmetric cascaded Multilevel inverter. The objective is to determine a PWM switching strategy which optimizes inverter performance by ensuring higher DC link utilization and minimum Total Harmonic Distortion (THD) at low switching frequency to minimize switching power losses also. Simulations carried out in Matlab-Simulink environment has given an insight of inverter performance when carrier based PWM techniques are applied. In this parametric evaluation both odd and even multiples of 50 Hz modulating signal were applied for obtaining switching frequency for various Multicarrier based PWM strategies.
Keywords: Multilevel; inverter; carrier based PWM; modulation index; phase disposition; Inverted sine.
A Modular DC-DC Converter with Zero Voltage Switching Capability
by Farzad Sedaghati, Reza Haghmaram
Abstract: A bidirectional DC-DC converter with high power density is proposed in this paper. The presented converter provides power transfer in both directions only with adjusting phase shift angle. Zero voltage switching (ZVS) in both turn on and turn off moments of all switches is the major capability of the converter that makes it suitable for high power applications. ZVS of the converter is provided without any auxiliary devices. High frequency transformers are employed in the converter configuration to match the converter two sides voltage. Moreover, the transformer leakage inductance along with external auxiliary inductance acts as energy storage in power transfer from one side of the converter to the other side. Steady state operation of the converter is analyzed. ZVS criteria of the proposed converter are studied and finally, experimental measurement results of laboratory scale prototype are presented.
Keywords: DC-DC converter; modular converter; ZVS operation; high-frequency isolation.
A Comparative Closed-Loop Performances of a DC-DC Switched-Mode Boost Converter with Classical and PSO based optimized Type-II/III Controllers
by NIRAJ RANA, ARNAB GHOSH, SUBRATA BANERJEE
Abstract: The DC-DC switched-mode Boost converter is well-known for its extensive applications ranging from few watts to several megawatts in different engineering fields. In this paper, a closed-loop Boost converter has been designed and implemented by using classical and particle swarm optimization (PSO) based optimized Type-II/Type-III controllers. The closed-loop control for Boost converter is difficult due to presence of a right-half-plane zero, and it is problematic for the conventional PID controller to exhibit good closed-loop performance with line, load changes and parametric uncertainty. The comparative studies between the closed-loop performances of the proposed Boost converter with classical and optimized Type-II/Type-III controllers have been produced. Simulations & experimental results are provided to demonstrate the effectiveness of proposed optimized controllers for the Boost converter. It is found that the PSO optimized Type-III controller exhibits better stability & closed-loop performance than the others reported controllers in this paper.
Keywords: DC-DC Switched-Mode Power Converter; Boost Converter; Non-Minimum Phase System; Classical Type II/III Controller; Particle Swarm Optimization; Optimized Type-II/III; Simulation and Experimental Results.
Fuzzy-PI Controller Applied to PMSM Speed Controller - Design and Experimental Evaluation
by Hicham Fadil, Mohamed Larbi Elhafyani
Abstract: Several advantageous are offered by synchronous motors with permanent magnet (PMSM) which are required in numerous fields for high performance adjustable speed operation. However, PMSMs speed control is related to directly to controllers and it needs to be adjusted using an appropriate regulator. In this paper, a proportional integral (PI) regulator applied for PMSM speed adjusting is considered and enhanced using a Fuzzy logic process by making that PI regulator gains self-adapting and ensures a good performances of the controller in transient states. A PMSM motor controlled using an eZdsp F28335 board is exploited to validate MATLAB/SIMULINK software results, and to show Fuzzy-PI improvement and performance under many constraints.
Keywords: Fuzzy-PI regulator; Permanent magnet synchronous motor; PI controller; speed control.
Power Sharing Control Strategy of Parallel Inverters in AC Microgrid Using Improved Reverse Droop Control
by Chethan Raj D, Dattatraya N. Gaonkar, Josep M. Guerrero
Abstract: Microgrid structure is developed on the basis of distributed generation units. Microgrid distributed generation units and energy storage devices are connected through inverters interface to the point of common coupling. Micro-grid system with multiple inverters, the use of conventional direct and reverse droop control method will cause uneven distribution of power, which is due to the difference between the output impedance and the line impedance of the inverter. In this paper, the traditional reverse droop control method is introduced and the power distribution of inverter output impedance is analyzed, and the defects of traditional reverse droop control are pointed out. Adding virtual resistor in the control loop of reverse droop control improves the power sharing and stability of operation, but also leads to the voltage drop in microgrid. To compensate the output voltage deviation, secondary control is proposed. Simulation results show the correctness and effectiveness of the proposed control strategy.
Keywords: Droop control; reverse droop control; distributed generation; inverters; microgrid; output impedance; secondary control; virtual resistors.
Cascaded H-Bridge Inverter with Reduced Device Count Control Considering Harmonic Distortion Minimization
by Faouzi Armi, Lazhar Manai, Mongi Besbes
Abstract: In this paper, a serial/parallel cascaded H-bridge (CHB) multilevel inverter is presented. The topology has the advantage of reduced number of switching devices, DC-sources and gate driver circuits. Consequently cost and complexity are greatly minimized, providing the same number of output voltage levels even more compared to conventional structures and other topologies given in some recent literatures in which authors have proposed new topologies with reduced circuit devices count (RDC).
The main contribution of this work is the ability to choose a set of harmonic order to be eliminated; in other similar works PWM technique is only capable to minimize total harmonic distortion (THD) without eliminating selected harmonic which require a complex output filter.
The feasibility and effectiveness of the proposed topology is evaluated with intensive simulation study and experimentally tested on a prototype using a field-programmable gate array (FPGA) to implement N-R algorithm for inverter selective harmonic elimination (SHE) control.
Keywords: Serial/Parallel CHB multilevel inverter; Reduced Device Count; Newton Raphson algorithm; Switching angles; SHE; THD; FPGA.
Study of Complex Dynamics in DC-DC Boost Converter with dSPACE based Real Time Controller
by ARNAB GHOSH, NIRAJ RANA, SUBRATA BANERJEE
Abstract: Switching converter circuits are nonlinear and time-varying in nature. In this paper, the complex dynamics in voltage mode controlled (VMC) DC-DC Boost converter has been investigated through simulation and experimentation. The converter is controlled by naturally sampled constant frequency pulse width modulation (PWM) signals in continuous conduction mode (CCM) and converter exhibits fundamental, quasi-periodic & chaotic oscillations for the variation of circuit parameters. In simulation study, the model of Boost converter is computed by non autonomous differential equations and finally the computational waveforms have been verified with experimental results. In order to verify simulation study, a laboratory scale prototype of closed-loop Boost converter has been fabricated. The closed-loop converter is controlled by dSPACE in real-time platform. The results obtained from simulation and experimental study have been presented and compared. It has been observed that the route to chaos is achieved by the slow-scale instability in this proposed study.
Keywords: Boost converter; voltage mode control; phase-portraits; dSPACE controller; chaos.
A REAL TIME IMPLEMENTATION OF INTERLINE DYNAMIC VOLTAGE RESTORER FOR IMPROVEMENT OF POWER QUALITY
by Ramchandra Nittala, Alivelu M. Parimi
Abstract: Voltage deviations which occur frequently in the form of voltage sag/swell cause severe disturbances and damage sensitive loads present on the distribution side of power system. One of the feasible solutions to mitigate these voltage sags/swells is by utilizing FACTS devices. The FACTS device proposed in this paper is Interline Dynamic Voltage Restorer (IDVR) which contains two or more Dynamic Voltage Restorers (DVR) with a common DC link. In this paper, IDVR is designed for a specific application to mitigate power quality problems in an existing real time load. A case study of the load network data of BITS Pilani Hyderabad Campus in Telangana, India which is spread over 200 acres is considered as the real time load. Various multiple voltage sag/swell scenarios are analysed in the real time load. The results have proven that the IDVR can effectively mitigate multiple voltage sags/swells in the considered real time load.
Keywords: Interline Dynamic Voltage Restorer (IDVR); Power Quality; Voltage Source Inverter (VSI);Voltage Sag/Swell.
Three Level Inverter Based Unified Power Flow Controller
by Khoukha BERRAHAL, Abd El Malek BOUHENTALA, Ahmed BENSALEM
Abstract: Unified Power Flow Controller is a power electronics based device utilized to improve transmission line capacity and control power flow transmitted by power transmission systems. This paper presents the application of the decoupled control strategy to control independently active and reactive power in the event of changes in the step points of the powers. Two types of controllers are used to handle the control strategy proposed: conventional PI regulator and fuzzy logic PI regulator. The fuzzy logic controller must have high performance to handle the problem of adjustment of power decoupling. Also, a three level Neutral Point Controller inverter is used in both series and shunt parts of the UPFC to get multistep voltage wave and improve the power quality.
Keywords: GTO;power flow control;UPFC;FACTS.
Hexagon Hysteresis Current Control Based STATCOM for Grid Connected Wind Turbine System
by Munireddy Gundala, Gowri Manohar T
Abstract: The use of renewable power sources, like wind power, has been increased recently due to climatic changes caused by fossil fuels and fast depletion of fossil fuels. This has lead to the tremendous increase in the interconnection of wind turbines to power system grid. This interconnection of wind turbines on a large number in to grid causes problems such as power quality, maintaining system voltage, reactive power compensation, control of grid frequency and aspects of power system grid stability. In this paper, STATCOM utilizes Hexagon Hysteresis Current Controller (HHCC) to improve the power quality. The proposed control scheme supplies the required reactive power to the system and thus relieves the source, leading to unity power factor (UPF) at the source and also it injects currents to reduce THD to satisfy IEC standard. In the proposed HHCC, the current control has been achieved by transforming the three phase (a, b, c) system in to stationary (α, β) reference frame and the complex space vector concept is employed. Further, the proposed systems dynamic response has been studied and the results have been presented.
Keywords: Wind Turbine System; Static Synchronous Compensator; Hexagon Hysteresis Current Control; Battery Energy Storage System; Total Harmonic Distortion.
An Efficient Crowbar to Improve the Low Voltage Ride-Through Capability of Wind Turbines Based on DFIG Excited by an Indirect Matrix Converter
by Ahmad Khajeh, Reza Ghazi, Mohamad Hosseini Abardeh, Mahmoud Oukati Sadegh
Abstract: Due to numerous advantages, in this work the traditional Back-to-Back converter is substituted with an Indirect Matrix Converter (IMC) to control the doubly-fed induction generator (DFIG). The recent grid codes require that the wind turbines must have the low voltage ride-through (LVRT) capability. One of the main challenges of the IMC that slows down the industrial applications is the fault currents handling. In this paper a new low cost, simple and reliable method is proposed to protect the IMC from large fault currents. This method is based on a novel crowbar structure. The PSIM simulation results confirm the efficiency of the proposed method in satisfying the new LVRT standards. Also, experimental results of a laboratory prototype verify the effectiveness of the proposed method.
Keywords: Wind turbine; DFIG; Indirect matrix converter; Low voltage ride-through; Crowbar.
Artificial Neural Network (ANN) based Power Quality Compensator
by Dr P. N. Tekwani, Ashwin Chandwani, Sagar Sankar, Neel Gandhi, Siddharthsingh Chauhan
Abstract: A reliable and efficient adaptive neural network based active power filter to estimate and compensate harmonic distortion from supply mains is presented in this paper. Now-a-days, there is drastic rise of current and voltage harmonics in power systems, caused by nonlinear loads. Active Power Filters (APF) are used to mitigate harmonics and thereby improve power quality. This paper deals with application of artificial neural network in shunt active power filter which provides ease in implementation and fast dynamic response compared to conventional active power filters. In depth analysis of neural network applications in the intelligent control and estimation for power quality compensation is presented in this paper. Here, both, reference compensating current generation scheme as well as current controller for the active power filter are developed using artificial neural network technique. Effective compensation provided by the proposed artificial neural network based shunt active power filter is proved through simulation results. Experimental analysis carried out using dSPACE DS1104 also validates power quality improvement by the proposed APF scheme.
Keywords: Artificial Neural Network; Hysteresis Current Controller; Power Quality; Shunt Active Power Filter.
DESIGN AND ANALYSIS OF DISCRETE PID CONTROLLER FOR LUO CONVERTER
by Shenbagalakshmi Rengamani, Vijayalakshmi Subramanian, Geetha Krishnan
Abstract: A thorough and effective analysis of the positive output super lift Luo converter along with the discrete PID controller has been carried out. The converter is designed to operate under continuous conduction mode and modeled using state space averaging method. The closed loop control is based on time domain approach and current mode discrete PID controller thus designed tunes the system in such a way that the converter specifications are satisfied. The Luo converter along with the controller thus designed is robust, shows stiff output voltage regulation without any overshoots or undershoots and highly efficient. The steady state error is almost zero. Extensive simulation is carried out and the results are illustrated. The controller platform is verified using LabVIEW.
Keywords: closed loop control; current mode control; dc-dc converter; discrete PID controller; Positive Output Super Lift Luo converter (POSLL).
Stability Improvement of Power System with Connected Wind Turbine Using Three Levels STATCOM
by Ahcene Bouzida, Radia ABDELLI, Abderrazak AIBECHE, Aimad BOUDOUDA
Abstract: The penetration of Doubly Fed Induction Generator (DFIG) into the power grid has become an important concern for power system engineers today. Voltage stability is an important factor to maintain the wind farm in service during some abnormal operating conditions. This paper deals with the integration of Synchronous Static Compensator STATCOM to overcome the voltage stability issue for the power systems with connected wind turbine. A dynamic model for the wind turbine equipped with DFIG and connected to the power system has been presented and the integration of a STATCOM as a dynamic reactive power compensator to maintain stable voltage and protecting the DFIG has been studied during a severe low voltage condition. The developed system is simulated and the results demonstrate that the good control of STATCOM enhances voltage regulation as well as transient stability of the variable-speed wind generators system during three phase faults. Many verifications based on time-domain simulations for powers, voltages and currents have been presented in order to show the STATCOM capability in improving transient stability of the studied power system.
Keywords: STATCOM; Wind turbine; Transient stability; DFIG; Power compensation; Voltage Regulation.
MODELING, DESIGN AND IMPLEMENTATION OF QUADRATIC BUCK CONVERTER FOR LOW POWER APPLICATIONS
by Ravindranath Tagore Yadlapalli, Anuradha KOTAPATI
Abstract: This paper discusses the modeling, design and implementation of Quadratic Buck Converter (QBC) for low voltage CPU voltage regulator applications. The small-signal modeling of QBC is characterized by state-space averaging technique. The QBC has been applied with Average Current-Mode (ACM) control strategy in order to evaluate steady sate as well as dynamic performance. The hardware development of QBC is exploited using FPGA controller. The PSIM simulation results are validated with the experimental results in terms of line and load regulations. It can be verified from results that the system stability is guaranteed for a wide range of operating conditions.
Keywords: Switched-Mode power supply (SMPS); Right-half-plane zeros (RHPZ); Average current-mode (ACM) controller; Transient settling time (TST); Transient voltage deviation (TVD).
Digital Variable Switching Frequency Controlled Integrated Power Converter for Class C & Class D Appliances
by Mopidevi Subbarao, Ch SaiBabu, S. Satyanarayana
Abstract: Existing methods for integrated switched mode power converters are mainly based on voltage controller technique, but they fail to comply with international regulatory standards (IEC 6100-3-2 and IEEE 519-1992) for class C and class D electrical appliances. Variable switching frequency current controller has been proposed in this work, owing to its features, viz- fast dynamic response, no compensation circuit and less complexity in design. Integrated converter for 100W load operating in universal range of voltage (90V-230V), 50Hz has been designed and implemented using MATLAB/Simulink, verified in hardware using TMS320F2812 digital processor board and thus results found to be complying with international regulatory standards.
Keywords: Switched mode power converter; Variable switching frequency; IBFC; Integrated Converter; power Factor correction; DSP.
Modular Switched Mode Power Supply, Tested With DC Motor Load
by Kandadai Nagaratnam Srinivas
Abstract: A modular switched power supply fit to be used as a standby supply in the electrical laboratories or in the industrial work floors is proposed in this paper. Conventional switched power supply involves bulk transformers. Various disadvantages arise due to this bulkiness. This work makes an attempt to address this issue and proposes a solid state switched power supply. The description of the proposed circuit, simulation of its operation and the working model are presented.
Keywords: Modular switched power supply; DC supply; solid state devices.
Non-isolated High Gain Bidirectional DC-DC Converter: Design and implementation
by Adel Karami, Ali Nahavandi, Bahman Eskandari
Abstract: This paper proposed a non-isolated bidirectional dc-dc converter with high step-up/down voltage gain. This converter has the ability to transfer the energy in both directions. The proposed converter uses three inductors that are coupled together pairwise with same winding turns. In step-up mode; the inductors operate in parallel in charging mode and series in discharging mode. In step-down mode; the inductors operate in series to be charged and parallel to be discharged. The proposed converter has higher step-up and step-down voltage gains than the conventional bidirectional dc-dc boost/buck converter. Simulations are obtained by using PSCAD/EMTDC software and the results are presented. Finally a laboratory prototype is implemented to validate theoretical analysis.
Keywords: Non-isolated; bidirectional dc–dc converter; coupled inductors.
Development and experimental validation of fault detection and diagnosis method in SPWM modulated symmetric cascaded H-bridge multilevel inverter
by Nithin Raj, Anjali Anand, Jagadanand G, Saly George
Abstract: This paper discusses gate open-circuit fault detection and diagnosis method in SPWM modulated symmetric cascaded H-bridge multilevel inverter. First, an output voltage modelling under fault condition in cascaded H-bridge multilevel inverter is presented. Further, simulations of fault conditions have been carried out for the development of the fault detection and diagnosis method. Based fault modelling and simulations, a fault detection and diagnosis method have been proposed based on the mean values of the bridge voltages as the diagnostic feature. Further, the proposed method has been validated experimentally on a 5-level symmetric sine pulse width modulated cascaded H-bridge multilevel inverter.
Keywords: cascaded H-bridge (CHB); fault detection and diagnosis (FDD); fault modelling; gate open-circuit fault; sine pulse width modulation (SPWM); multilevel inverter (MLI).
Analysis and Design of Novel Non-Isolated Quadratic Boost DC-DC Converter.
by Subhendu Bikash Santra, Tanmoy Roy Choudhury
Abstract: This column elucidates analysis and design of novel single switch non-isolated quadratic boost converter. The operating principle is discussed both in CCM and DCM mode. Analysis includes closed loop average current mode control. The proposed converter exhibits stable operation under input voltage and load change. Linear control theory is applied for the loop compensator design. The suitability of the proposed scheme is well visualized and validated through simulation results procured using PSIM 9.1.1 and experimental results obtained from a practical 75 watt converter. The converter is designed for 75 Watts with 89-90% measured efficiency, where voltage and current ripple is 2 % of output voltage and 1 % of rated inductor current, respectively.
Keywords: Quadratic Boost converter; CCM and DCM mode; Voltage stress; Voltage step-up ratio; Current mode Control; Efficiency.
Adaptive RBF Neural Network Based on Sliding Mode Controller for Active Power Filter
by Huiyue Zhang, Yunbo Liu
Abstract: In this paper, an adaptive radical basis function neural network (RBFNN) is proposed to deal with dynamic tracking error problems which is the mathematic model uncertain or complex for the three-phase active power filter (APF). The adaptive RBFNN systems are employed to approximate the system function term in the sliding mode controller. Different from back propagation neural network (BPNN), RBFNN is local uniformly convergence so that it enhance the convergence speed of weights. According to Lyapunov stability analysis guarantee the control algorithm stable implementing that is working out the adaptive law and dragging the states onto the sliding surface and sliding along it. This approach is almost model-free requiring a minimal amount of a priori knowledge and is robust in the face of parameter changes. The simulation results of APF demonstrate the outstanding compensation performance and strong robustness.
Keywords: APF; RBF neural network; Sliding Mode Controller; Active Power Filter.
Design and Implementation of a Novel Single Phase Universal Power Converter
by Mudadla Dhananjaya, Swapnajit Pattnaik
Abstract: Universal power converter have drawn the attention of researchers in the recent past, as they can be used for dc-dc, dc-ac, ac-dc, ac-ac and variable frequency conversion. In this paper a novel universal power converter has been proposed with a simple switching structure which is formed by the reduction of device count as compared to individual conventional converters. Further, it will give the most economic operation with less complexity and compact in size. This converter can be configured as dc-dc, dc-ac, ac-dc, ac-ac and cycloconverter. The operation of the proposed converter in all configurations have been discussed. The proposed converter is simulated in MATLAB environment to evaluate its performance and experimental results are verify with simulation results.
Keywords: dc-dc converter; dc-ac converter; ac-dc converter; ac-ac converter and cycloconverter.
A New EABC for DC-link Capacitor Voltage Equalization of MPC based 5-L HPFC
by Naveen Yalla, Pramod Agarwal
Abstract: In this paper, a new multi-device unidirectional buck boost topology is proposed to equalize the DC link capacitor voltages of multi-point clamped (MPC) based five-level high power factor (HPF) converter. Two independent controlled chopper topologies (consisted with two parallel connected control devices and one single uni-directional diode) makes the proposed topology effectively and efficiently to mitigate the deviation of DC link capacitor voltages, which is caused due to voltage drift phenomena. The desired pwm signals are generated by a phase shift control strategy. Proposed configuration provides two times ripple frequency current through the inductor, which can contribute less inductor size, all most 50% of traditional one, and therefore the lesser weight of the core and its corresponding losses. The contribution of proposed topology is analyzed mathematically and results are verified by simulation as well as prototype experimental setup.
Keywords: AC/DC power conversion; External auxiliary balancing circuit; Multi point clamped; Multi level converter; High power factor converter.
An Improved Topology of Cascaded Multilevel Inverter with Low Switch Count
by Bikram Das, Manas Patra, Debashis Chatterjee, Aniruddha Bhattacharaya
Abstract: An improved topology of a multilevel inverter is described in this paper. Proposed topology is comprised of the basic module to get positive levels at the output. An H-bridge can be formed to obtain ac output. Developed topology significantly reduces the number of IGBTs, DC voltage sources, gate drivers for the same number of levels. Different algorithms are presented to determine the number of levels, switches and total blocking voltage. Comparison of the proposed topology with the conventional cascaded multilevel inverters and other existing topologies in the literature has been carried out to show the advantages of the newly proposed topology. The operation and performance of the proposed multilevel inverter are verified by suitable experimental results with a single phase 15-level multilevel inverter considering resistive and inductive loads.
Keywords: Cascaded Multi level inverter; reduced switch; Loss comparison; total standing voltage,H-Bridge;.
Increasing quality of SMPS through proper design of a high-frequency transformer
by Michal Frivaldsky, Pavol Spanik, Viliam Jaros, Andrej Kanovsky
Abstract: High frequency transformer significantly influences power losses, power density and efficiency of isolated power converter. With optimal design of high frequency transformer high efficiency and power density can be obtained, what is necessary for achievement of the upcoming regulations and standards for dc-dc converters. This paper deals with verification of the design procedure of high frequency transformer, which id oriented for high efficiency achievement of switched mode power system. Simulation model of dc-dc converter with precise model of high frequency transformer is developed for the verification purposes. The proposed procedure servers for optimal selection of best solution for high-frequency transformer in terms of ferrite material as well as shape of magnetic core.
Keywords: efficiency; transformer core; core shape; ferrite material; high frequency,.
Synchronous Reference Frame Sliding Mode Observers for the Inverse of the Rotor Time Constant of the Induction Motor
by Mihai Comanescu
Abstract: The paper discusses the problem of inverse rotor time constant estimation for the induction motor (IM) and presents two sensorless sliding-mode observers (SMOs) that are constructed using synchronous reference frame models. Estimation is done assuming that the magnitude of the flux is available. A voltage model observer is used to estimate the αβ fluxes: these are used to compute the field-orientation angle and the flux magnitude. The paper develops an observer based on the first-order model; however, this does not perform well under parameter variations. A second observer is developed using an augmented model (which now involves the speed of the motor) this is transformed into a sensorless design by feeding it with a speed estimate (assumed inaccurate). It is shown how to design the feedback gains in order to reduce the sensitivity of the estimate to the input speed error. The theoretical developments are supported with simulations and experiments.
Keywords: induction motor control; voltage model observer; sliding mode observer; rotor time constant estimation.
Design and Performance Evaluation of Self-Supported Dynamic Voltage Restorer for Mitigating Various Power Quality Problems
by Shubhendra Pratap Singh, Abdul Hamid Bhat
Abstract: Dynamic voltage restorer (DVR) is used to shield voltage sensitive loads from harmonic distortion and sag/swell in supply voltage consistently. In this paper, a self-supported dynamic voltage restorer (DVR) is discussed. The control methodology based on calculation of unit templates is used for dynamic voltage restorer (DVR). Fundamental of terminal voltage is extracted by using the synchronous reference frame (SRF) theory and the reference load voltage is obtained. The comparison is done between the reference load voltage and the sensed load voltage to generate the error signal and this error signal is processed by the pulse width modulation (PWM) controller to generate the control pulses for voltage source converter (VSC) of dynamic voltage restorer. In this paper, designing of main system parameters such as VSC-DC link capacitance, ripple filter, AC side inductance and Insulated gate bipolar transistor (IGBT) based VSC rating is given in detail. In the capacitor supported dynamic voltage restorer, injected voltage is in quadrature with line current so there is no need of active power injection during steady state. At the time of any disturbance in supply side, dynamic voltage restorer only supplies or absorbs the reactive power to maintain the load voltage constant. By using MATLAB/Simulink simulation studies, the above control strategy is tested. The simulation results for voltage harmonic distortion, voltage sag/swell and voltage unbalancing demonstrate the viability of DVR controller.
Keywords: Dynamic voltage restorer (DVR); Voltage sag/swell; Total harmonic distortion (THD); Power quality; Custom power devices; Fuzzy logic controller (FLC).
Performance Analysis of SPRS based Induction Motor Drive using Multi-level Inverter and Buck-Boost Chopper
by Sita Ram Bhardwaj
Abstract: This paper presents the performance analysis of induction motor drive (IMD) utilizing slip power recovery scheme (SPRS) with two and three level voltage source inverter (VSI) and buck-boost chopper employing gate turned off thyristor, metal-oxide semiconductor field effect transistor, insulated gate bipolar transistor as switching devices. A mathematical model of 2 hp, 400V, 50Hz, 1440 rpm IMD has been developed and Simulated in MATLAB. The performance parameters taken for induction motor drive are reactive power, power factor, efficiency, and total harmonic distortion (THD) of the supply. The novelty of proposed scheme lies in the implementation of simulation model of SPRS using three level inverter and buck-boost chopper from the dynamic model library of MATLAB/Simulink. The simulation results have shown that two-level VSI with chopper controller has enhanced the power factor and efficiency of IMD compared to the SPRS without chopper. The three-level inverter has reduced the reactive power consumption and THD, consequently, enhanced the quality of power supply.
Keywords: Buck-boost chopper; efficiency; induction motor drive; inverter; power factor; slip power recovery scheme.
Comparative Analysis of Non-Inverting Buck Boost Converter Topologies for Fuel Cell Low Voltage Applications.
by M.Venkatesh Naik
Abstract: The FC sources are unregulated voltage sources and require power converter devices to get a regulated output voltage. When these devices are used in low voltage low power applications DC-DC buck boost converters (BBC) are required to get the regulated voltage on load side. The multi device multi switch operation of the buck boost converters are usually employed for successful operation of the FC stacks. In this paper, the different non inverting type of buck-boost converters i.e., Buck Boost Converter (BBC), Multi Device Buck Boost Converter (MDBBC), Interleaved Buck Boost Converter (IBBC), and Multi-Device Interleaved Buck Boost Converters (MDIBBC) are analyzed and comparative study among them are presented with respect to the parameters like, ripple current, component size, power losses and efficiency. The comparative study demonstrates that the multi device converter topologies are more efficient than the other converter topologies employed in low voltage low power applications.
Keywords: buck boost converters; ripple current reduction; fuel cell low voltage applications.
Rotor Vibration Control of Hybrid Pole Bearingless Switched Reluctance Motor with C-Dump Converter
by V.S.Sobhan Polamraju, G. V. Nagesh KUMAR, P.V. Ramana Rao
Abstract: Rotor vibration control during start up, acceleration and deceleration phases is one of the key problems besides stable levitation, in high-speed applications of bearingless switched reluctance motor (BSRM). In this paper, an effective intelligent sliding mode controller is proposed for suppressing the rotor vibration due to residual unbalance and external disturbance during levitation and motoring phases. The parameters of time-varying sliding surface for avoiding high control gains and chattering are adjusted integrating the sliding mode control (SMC) and features of fuzzy logic control. The experimental studies conducted on a prototype BSRM system confirm that the application of fuzzy SMC guarantees the robust performance with less chattering under model uncertainties and unknown external disturbances compared to classical sliding mode controller.
Keywords: BSRM; C-Dump Converter; Fuzzy Logic; Radial force control; Rotor vibration; SMC.
Modified GSA for Minimization of THD of Voltage Source Multilevel Inverter
by VARSHA SINGH, SWAPNAJIT PATTNAIK, Shubhrata Gupta
Abstract: Optimization techniques have always been a reliable friend while dealing with complex non-linear problems. Among a wide gamut of available optimization techniques, Genetic Algorithm (GA) has always stood out on account of its being flexible and adaptable. This paper is an attempt to find a worthy competitor to GA. In the process, a new heuristic algorithm Gravitational Search Algorithm (GSA) has been chosen for implementation. The new technique, GSA is based on the laws of gravity and mass interaction. In order to obtain an efficient solution and quick convergence to the problem of minimization of THD of the 15 level MLI under study; the algorithm is further modified. In the modified GSA (MGSA) the initial gravitational constant (Go) and the updating constant (α) are suitably modified. In this paper, SHE equations are used to find the optimum switching angles in both GA and GSA to minimize the total harmonic distortion (THD) of the inverter output voltage. The simulation and hardware results rendered by sinusoidal pulse width modulation (SPWM), GA, GSA and MGSA are compared for validity with each other. It is found that hardware results are in concurrence with the simulation results
Keywords: GSA; MGSA; GA; MLI; SPWM; THD; power quality.
DC DC Buck Converter with Second Order Sliding Mode Control: Analysis Design and Implementation
by Brijesh Naik, Axaykumar Mehta
Abstract: This article discusses about the analysis, design and implementation of the DC DC Buck converter with the Second Order Sliding Mode Control (SOSMC) or 2-sliding control. Also, performance of the converter is tested for both classical sliding mode control and the SOSMC. The analysis of DC DC Buck converter with the SOSMC is presented. The output feedback is used. The bounds of controller parameters are obtained to assure stability. The systematic implementation guidelines are provided. Effects of varying controller parameters are explored with simulation and experimental results. Effects of the load disturbance are also studied. It is shown that the use of SOSMC reduces the chattering in the controlled variable i.e. the load voltage of the converter. Finally, the simulation and experimental results are presented.
Keywords: higher order sliding modes; 2-sliding control; sliding mode control; buck converters; chattering alleviation.
Universal Control Algorithm for Automatic Current Regulated LED Driver
by Vishwanath Gupta, Biswarup Basak, Kamalika Ghosh, Biswanath Roy
Abstract: In the present work a universal control algorithm is proposed which automatically regulates the output current of an LED driver as per the connected load requirements. The unique features of the proposed control algorithm is its operability in a wide output power range and remaining unaffected by the unequal current sharing among the LED strings arising due to mismatch among same wattage LED chips. The proposed control algorithm is tested by modelling and simulating an LED driver in MATLAB SIMULINK to operate LED modules having series-parallel combination of 3W LED chips in the range of 18W-72W. The results obtained from simulation show that the proposed control algorithm successfully regulates the output current of the LED driver according to load requirements. The electrical performance of the simulated LED driver on universal AC supply complies with IEC 61000-3-2:2014 Class C regulations and shows significant improvement over previously proposed LED drivers.
Keywords: Universal control algorithm; automatic current regulation; LED driver; LED modules; modelling and simulation.
Novel Classifier Design for Optimizing the Accuracy for Identification of Disturbance in Power System
by Devi Vighneshwari
Abstract: Origination of the disturbances in the power system is not a new problem and various technologies have evolved while various research-based contributions have addressed this problem to a large extent. Reviewing existing techniques shows much usage of iterative optimization while designing the classifier. Hence, higher accuracy arrives at the cost of computational complexity in the existing system. Therefore, the proposed system introduces a novel framework where short-time Fourier transform is applied on the numerical-modeling on power signal generation corresponding to practical stages of various disturbances. A simple and novel feature extraction process is applied, which causes the system to enhance its potential for the classification process. Adopting IEEE 1159 standard, the disturbances of power system has been modeled, which is trained using dual-layer feedforward network. Comparative analysis shows proposed system outperforms conventional techniques by offering higher accuracy with lower computational complexity. From the analysis, it is observed that the proposed concept of detection offers higher accuracy of the classification within extremely very less iteration with less execution time of 2.6551sec.
Keywords: Power Quality; Power System; Disturbance; Classification; Identification.
Design and Analysis of Space Vector Pulse Width Modulation Techniques for Z-Source Inverter
by Satwant Singh, Santosh Sonar
Abstract: This paper presents the design, analysis and digital implementation of space vector PWM based various switching sequences for the Z-source inverter. Three main type of switching sequences have been taken, these are continuous switching sequence, basic bus clamping, and advanced bus clamping. Each of these sequences is designed in order to achieve symmetry in output line voltage. Two main control techniques, maximum boost, and maximum constant boost have been used to analyze each sequence in terms of switching transition per sample and duration of positive dc bus clamping. The novelty of the paper is the design of all switching sequence considering the conditions of symmetry and the implementation of advanced bus clamping techniques in the area of Z-source inverters. Simulation and experimental results have been presented to verify the design.
Keywords: Z source inverter (ZSI); space vector pulse width modulation (SVPWM); maximum boost control (MBC); maximum constant boost control (MCBC); shoot through (ST) state; non-shoot through(NST) state.
Enhanced Dynamic Performance in Grid Tied Bidirectional Converter with Direct Power Model Predictive Control
by Bhadra R Warrier, A. Vijayakumari, Sasi K. Kottayil
Abstract: : A direct power control is envisaged as a preferable choice for control of grid tied converters in the future. Expulsion of additional power computations will improve the dynamic response of the control thereby making it fit for quick acting micro-grids. The work presented tweaked the basic model predictive control to provide a reference computation directly from power references based on the instantaneous pq theory. This added feature utilizes the predictive system model to estimate grid voltage in contrast to conventional method of sensing it from the system, and further compute the current references directly from applied power references. While keeping other merits of model predictive control like good harmonic profile and accurate reference tracking, the direct power model predictive control suggested here also ensures a seamless bidirectional power flow between inverter and rectifier modes of operation. A detailed analysis of the proposed control for multiple applications is attempted which validate its potential and proves its efficacy to be a fast, comprehensive and independent converter control scheme.
Keywords: Bidirectional grid tied converter; outer power loops; model predictive control; direct power control; transition time.
Evaluation of POD and APOD Multicarrier SPWM Techniques for Three Phase Seven Level Diode Clamped Multilevel Inverter fed Induction Motor Drive using FPGA
by Susheela Nunsavath
Abstract: Multilevel inverters have drawn tremendous interest in high power high voltage applications due to their merits such as reduced voltage stress on switches, lower EMI problems and reduction in THD The MLI technology is also advantageous in improving output waveforms due to the higher number of levels in the waveform of output voltage along with a reduced input filter size which is useful for grid connected applications. This paper focuses on implementation of three phase diode clamped multilevel inverter fed induction motor drive using various multicarrier based sinusoidal pulse width modulation techniques. The performance analysis of the inverter is carried out using phase opposition disposition (POD) and alternate phase opposition disposition (APOD) techniques. In addition to this, the comparison of the modulation methods is also analyzed. Simulation is performed using MATLAB/SIMULINK. The POD and APOD carrier based sinusoidal pulse width modulation techniques for three phase seven level diode clamped multilevel inverter are implemented on VPE Spartan 3A DSP board using Xilinx field programmable gate array (FPGA) and the experimental results are presented to validate the effectiveness of the operation of the seven level diode clamped multilevel inverter using PWM strategies.
Keywords: alternate phase opposition disposition (APOD); diode clamped multilevel inverter; field programmable gate array (FPGA); sinusoidal pulse width modulation (SPWM); induction motor; phase opposition disposition (POD).
Phase shift voltage regulating control technology in high voltage electrostatic precipitator power supply
by Jiahui Li, Huiyue Zhang, Zhengrong Jiang
Abstract: With the peoples health requirements and the development of industry, the electrostatic precipitator is widely used in many industrial areas, such as smelting, cement production, electric boilers and so on, as well as in household air purification. In order to improve the frequency of the converter and reduce the switching loss, a phase shift voltage control method based on PID control is introduced in this paper. A serious of problems are also be solved by the method, such as the uncertainty of electrostatic precipitator load, the characteristics of nonlinear and time-varying, and the uncertainty of stray parameters of high frequency transformer which is the core device of the electrostatic precipitator power supply. This method can make use of the stray parameters of high frequency transformer reasonably, so that the power device can work in soft switching state. In the same time, it is suitable for industrial mass production with lower cost but good effect. The results of simulations and experiments show that this voltage modulation mode makes the dusting power supply output 60kV voltage stably, and has good dynamic performance, which makes the dust removal system more robust.
Keywords: The power supply of the high frequency and high voltage electrostatic dust removing ; PID control; Phase shift voltage regulation; Robustness.
Particle Swarm Weighting Factor Optimization for Predictive Control of Three Level Inverter with Balanced Voltages
by Zakaria Lammouchi, Kamel Barra
Abstract: The paper presents a design procedure of weighting factor optimization for finite states model predictive direct torque and flux control of an Induction Machine (IM). The multilevel converter feeding the machine is a Three Level Neutral Point Clamped Voltage Source Inverter (3LNPC-VSI). The flexibility of the predictive method permits to control simultaneously the torque, the flux and the DC link input voltage of the source. The cost function uses at least one weighting factor adjusted to satisfy desired performance. The chosen value of this factor may not be suited for all ranges of operating points and finding these values are very time consuming and complex. The main aim of this paper is to propose an online optimization of the weighting factor by the Particle Swarm Optimization (PSO) approach well known by its robustness and fast convergence to the global optimum. Simulation results show that PSO strategy is very efficient to design accurately and quickly these weighting factors.
Keywords: Induction motor; predictive control; cost function; multilevel converter; balanced DC link voltage; weighting factor; particle swarm optimization.
MODELLING AND EXPERIMENTAL VALIDATION OF ELECTRICAL CHARACTERIZATIONS OF HIGH SPEED FLUX REVERSAL GENERATOR
by Vidhya Bheeman, K.N. Srinivas
Abstract: This paper makes an attempt to provide a comprehensive documentation of characterization of high speed Flux Reversal Generators (FRG). At first, a conventional design of FRG is proposed for high speed application. Then for this machine, keeping the minimization of cogging torque as the major constraint, the design dimensions are fine tuned. A thorough static characterization and dynamic characterization on the finalized dimensions are presented. Finite element analysis is used for this purpose. Validation of the above characterizations has been made through an experimental setup. As magnetic material play an important part in the stator-rotor construction of high speed FRG, it is viewed that a novel soft magnetic material can enhance the performance of this machine. To this effort, a novel soft magnetic material called cobalt-iron (Hiperco 50A) is proposed whose analyses are also documented in this paper. As a whole, this paper can serve the purpose of a detailed electrical characterization of FRG, which forms the contribution of this paper.
Keywords: Flux Reversal Generator; Static characterization; cogging torque; Dynamic characterization; Soft magnetic material; Finite Element Method.
Low Power Digital On-Chip Implementation Of Fibonacci Non-Magnetic Switching Converter For IoT Applications
by Vivekanandan Subburaj, Debashisha Jena, Parthiban Perumal
Abstract: Power management (PM) block is one of the important block in system on chip (SoC). Non-Magnetic converters (NMCs) are more reliablernfor SoC since it is small in size and having low power level. Recently SoC is applicable to all Internet of things (IoTs). NMCs are havingrnthe capability to share more transformation voltage levels to different part of the ICs in order to obtain high efficiency. Compare to all rnNMCs, the Fibonacci converter generates different voltage level (i.e) 21 voltage levels in single PM block. Power frequency modulation (PFM) rncontroller is used to select and control different voltage levels. In this paper fully integrated digital controller rn(Verilog-HDL) based converter design is implemented using 180 nm technology for load current which is less than 1 $mu$A and consumes 10 $mu$W total rnpower with an area of 166 $mu$m X 205 $mu$m.
Keywords: IoTs; power management; Non-Magnetic; Integrated; Fibonacci; ICs.
MEMS 3D-MicroTransformer Fabrication on PCB Using Electrodeposition Method
by Mohammad Zayed Ahmed, Mohd Alrashdan, Amir Abu-Al-Aish, Burhanuddin Yeop Majlis
Abstract: A rectangular 3D- micro-transformer was designed, fabricated on a Printed Circuit Board using Micro Electro Mechanical System technology. The fabrication process included an electroplated copper coils and an Ni/Fe magnetic core. The 3D- micro transformer is aimed for low frequency applications. The total footprint of the micro transformer is 3.1744
Keywords: MEMS; Fabrication; PCB; 3D Micro-Transformer; Electrodeposition.
MULTI-VARIABLES, SINGLE OBJECTIVE OPTIMAL POWER FLOW OF IEEE-30 BUS SYSTEM USING PARTICLE SWARM OPTIMIZATION, ARTIFICIAL BEE COLONY, AND CUCKOO SEARCH ALGORITHMS
by Mohd Alrashdan, Abed-Al-Rahman M.S Al-sharqi, Mutasem Al-Sharqi
Abstract: Particle Swarm Optimization (PSO), Artificial Bee Colony (ABC), and Cuckoo Search (CS) nature-inspired algorithms used extensively to solve optimization problems in different fields of engineering, including Optimal Power Flow (OPF) in power distribution systems. In this paper, MATLAB software was used to optimize multi-variables including the fuel cost, power losses and voltage deviations in IEEE-30 Bus System as one objective function based on PSO, ABC, CS algorithms. The ABC algorithm shows the lowest objective function of 978.78025, the best fuel cost of 830.54 ($/h), best power losses of 6.1235 (MW) and voltage deviation of 0.14417 (p.u.). While the CS algorithm showed the moderately objective function of 984.7569, PSO search algorithm has the highest objective function of 1067.6442. These three algorithms approve each other in OPF and confirm the usage of this algorithm in combining several variables in one objective function.
Keywords: IEEE-30 Bus System; Optimal Power Flow; Particle Swarm Optimization; Artificial Bee Colony; Cuckoo Search; fuel cost; power losses; voltage deviations.
Different Artificial Intelligence Strategies to Control an Inverter of an Active Power Filter for Power Quality Improvement
by Ouarda Lahmadi
Abstract: Active Power Filter (APF) is the best solution to minimize harmonic contamination drawn from nonlinear loads, but its effectiveness is strictly dependent on how quickly and accurately its control algorithms can perform. In this paper, performance of APF is analyzed for various types of artificial intelligent current controllers which are used to generate switching signals of the Voltage Source Inverter (VSI). Three efficient and reliable intelligent approaches were adopted. The first two are based on a PI-Neural regulator and the direct control using a Multi-Layer Perceptron Neural Network (MLP) respectively. The third one is based on the fuzzy logic regulator. These intelligent approaches are automatically able to adapt itself to any change in the parameters of the electrical network, no need accurate mathematical models and can work with imprecise inputs with easy implementation. So, the objective of this paper is to take advantages of these intelligent techniques to improve the compensation performance of the conventional APF and enhance the power quality. To control the operation of an APF, existing control algorithms are already used for harmonic extraction, DC-link capacitor voltage regulation and synchronization. In this paper, we propose to extend the use of the Adaptive Linear Neuron (ADALINE) to build a homogeneous computing structure. The proposed compensator APF-Neural, based on a complete neuromimetic strategy, for harmonics identification and control of three-phase VSI was tested under various operating conditions. Simulation results demonstrate the utility of our proposed structure for power quality improvement. We further show its effectiveness and robustness compared to the fuzzy and conventional current controllers.
Keywords: Adaptive compensation; Artificial intelligent controllers; Harmonic current compensation; LMS training algorithm; Multi-Layer Perceptron Neural Network (MLPNN); Shunt Active Power Filter (SAPF); Voltage Source Inverter control (VSI).
The maximum power tracking of variable step fuzzy logic control based on power prediction
by Zhixiang Hou, Jiqiang Hou
Abstract: The perturb and observe algorithm oscillates in the vicinity of maximum power point, and fixed step size can not be set on the premise of meeting tracking accuracy and speed. To locate the optimal operating point of photovoltaic power generation system and to solve the contradiction between tracking accuracy and speed, a variable step fuzzy logic control method based on power prediction is proposed. In other words, the variable step is introduced on the basis of power prediction method and meanwhile, the fuzzy logic control method is adopted control the variable step in real time to track the maximum power point. The comparison of simulation results of other methods, and that of the method proposed in this paper shows that the method proposed cant only track the maximum power point fastly, but also improve the dynamic performance and steady-state performance of the system. The experimental results prove the effectiveness and practicability of the algorithm.
Keywords: Photovoltaic power generation system; Maximum power point tracking; Variable step size; Fuzzy logic control.
A New Soft Switching PV Module-Integrated Boost DC-DC Converter
by Khairy Sayed
Abstract: Abstract- This paper introduces a new non-isolated soft switching boost PWM DC-DC converter utilizing a switched capacitor edge-resonant cell. The proposed converters can readily fulfill a higher voltage gain due to coupled-inductor which render as a transformer to magnify the voltage gain. At the same time, the boost inductor serves as a resonant inductor. The soft switching converter proposed here can achieve a zero-current soft-switching (ZCS) at turning-on and zero-voltage soft-switching (ZVS) at turning-off operations in the used active semiconductor switches. Those beneficial features enable a wider soft-switching range of operation with a higher step-up voltage ratio due to the auxiliary edge-resonance cell, which results in a higher efficiency and low losses. In order to demonstrate the effectiveness of the novel type boost converter, a small laboratory prototype is implemented by simulation and experimental setup using a standard 250-W, 72-cell PV module. Then, the operation performance of the proposed soft switching power converter is examined followed by the design guidelines of the proposed power converter and the results analysis.
Keywords: Boost DC-DC converter; Soft switching; ZCS; switched capacitor; edge resonant; module-integrated converter.
Enhanced Z- Source inverter based voltage frequency generator to conduct Induced over voltage test on Power transformers
by Geno Peter
Abstract: Abstract: Transformer is said to be the heart of an electrical power system. The life time of a well maintained transformer is well above 25 years. Frequent residual life assessment on transformers has to be done to extend the life time of the transformer. Testing of transformer is required, as its an indication of the extent to which a transformer is able to comply with the customers specified requirements and the respective standards. Testing is required to determine the condition of the Transformer in order to identify the most vulnerable component of the equipment. (IEC 60076-1). Before the development of Power electronic devices, motor generator set was used to generate the required voltage and frequency to conduct the induced over voltage test on power transformers. Static frequency inverter has replaced the noisy and bulky motor generator set. . In this paper, induced over voltage testing on power transformers using enhanced Z source inverter is discussed. First, the power transformer was fed with the required voltage and frequency using a conventional Z source inverter, and then with an enhanced Z source inverter using MATLAB platform and the performance is analyzed. Field testing was done with an enhanced Z source inverter circuit on a power transformer based on the simulation results.
Keywords: Transformer; motor generator; Z source; Static frequency Converter.
Artificial Neural Network based Multiport DCDC Converter for Simultaneous Power Management
by Ashok Kumar B., Angeline Ezhilarasi G
Abstract: In the paper, Artificial Neural Network (ANN) is proposed for providing the optimal operation of multiport dcdc converter. Here, the proposed controller is utilized to achieve the simultaneous power management of multiple renewable energy sources, which can be of different types and capacities. Initially, the modeling and control topology is designed after that, the principle and operation are analyzed. The proposed dcdc converter just uses one controllable switch in every port to which a source is associated. Along these lines, it has the benefits of straightforward topology and least number of power switches. The photovoltaic (PV) and Wind Turbine Generator (WTG) are considered as the sources and these are associated with the converter. The PV is worked in view of the maximum power point tracking (MPPT) controller and the WTG is associated with the battery source. The main objective of the paper is to achieve the simultaneous power management through the utilization of multiport dc-dc converter with ANN controller. The ANN works based on the input layer, one or more has hidden layers and the output layer. The proposed ANN controller is applied to get the optimal output of the converter. The input of the proposed controller is error voltage and the output is control pulses. The proposed converter is applied for simultaneous MPPT control of a wind/solar hybrid generation system consisting of one WTG and different PV panels. The proposed method is implemented in MATLAB/Simulink platform and their performances are evaluated. The performance of the proposed method is compared with the existing controller and PI controller. The simulation results are provided to validate the effectiveness of the proposed converter. Then the efficiency of the converter is also determined to evaluate simultaneous power management of the WTG and PV panels for converter.
Keywords: Multiport DC-DC converter; ANN; PI controller; voltage; WTG; PV.
Exponential Reaching Law and Sensorless DTC IM Control with Neural Network Online Parameters Estimation Based on MRAS
by Said Legrioui, Salah Eddine Rezgui, Hocine Benalla
Abstract: The most important problem in the control of induction machine (IM) is the change of its parameters, especially the stator resistance and rotor-time constant. The objective of this paper is to implement a new strategy in sensorless direct torque control (DTC) of an IM drive. The rotor flux based model reference adaptive system (MRAS) is used to estimate conjointly the rotor speed, the stator resistance, and the inverse rotor time constant. The process of the estimation is performed on-line by a new MRAS-based artificial neural network (ANN) technique. In addition, the drive is complemented with a new exponential reaching law (ERL), based on the sliding mode control (SMC) to significantly improve the performances of the control system compared to the conventional SMC which is known to be susceptible to the annoying chattering phenomenon. An experimental investigation was carried out via the Matlab/Simulink with real time interface (RTI) and dSPACE (DS1104) board where the performance of the proposed method was tested at different points of IM operation.
Keywords: DTC; MRAS; Induction Motor; Sliding mode; Exponential reaching law; Neural network ; Parameters estimation; dSPACE.
Analysis and design of IMC-PI Controller with faster set point tracking and disturbance rejection for Interleaved DC-DC SEPIC converter based Power Factor Correction
by Komathi Chandraselvam, Umamaheswari M.G
Abstract: This paper deals with the design of Internal Model Controller (IMC) - Proportional Integral (PI) controller for Interleaved DC-DC Single Ended Primary Inductance Converter (SEPIC) based Power Factor Correction (PFC). The transfer function of the proposed converter exhibits seventh order dynamics with complex right hand plane (RHP) poles and zeros. IMC based PI controller is used to achieve perfect control since it contains the internal model of the process implicitly or explicitly. The cascade control strategy is implemented for the proposed converter with IMC based PI controller as inner current and outer voltage controller. The dynamic and steady state performance parameters of the proposed scheme are evaluated using Matlab/ Simulink software. The simulation results reveal that the proposed scheme offers excellent stability characteristics, robustness, faster set point tracking and disturbance rejection for various uncertainties in the process as compared to conventional PI controller.
Keywords: Power Factor Correction; Internal Model Controller; PI Controller; Total Harmonic Distortion; Interleaved DC-DC SEPIC converter.
A Comparison of Different DC-DC Converter Topology for Electric Vehicle Charging
by Manaswi Srivastava, Arun Kumar Verma, Pavan Singh Tomar
Abstract: The dc-dc converter with soft switching technique is now a widelyrnaccepted industrial application/ electric vehicle. But it also deteriorate from some problems like duty cycle loss, conduction loss, circulating current loss, narrow range of soft switching, and voltage ringing. Some methods are proposed to rectify these problems to make the dc-dc converter more efficient. In this paper, typical auxiliary networks are analyzed and classified. The features and limitations of the dc-dc converters are compared. Finally, the characteristics of the dc-dc converter are summarized to choose the best topological architecture for electric vehicle application.
Keywords: Auxiliary Network; ElectricVehicle (EV); Topology; Soft Switching;rnZero Voltage And Zero Current Switching (ZVZCS); Zero Voltage Switchingrn(ZVS).
ANALYSIS,DESIGN AND IMPLEMENTATION OF A FIXED FREQUENCY PWM BASED SLIDING-MODE CONTROLLER FOR QUADRATIC BUCK CONVERTER
by Ravindranath Tagore Yadlapalli
Abstract: The dc-dc converters are well-known due to their nonlinear and time-variant nature. This paper addresses the investigation of a fixed frequency PWM based Sliding Mode Current (SMC) controller applied to Quadratic Buck Converter (QBC). The QBC is well-suited for very low voltage CPU VR applications with high-step-down dc-dc conversion ratios. The SMC control features the reference current profile generation, satisfaction of hitting, existence and stability conditions besides the selection of sliding surface parameters. The simulation of QBC is realized for 19V~8V/1V at 50 KHz using PSIM software. The experimental results are presented in order to validate the simulation results. The strength of this control strategy is analyzed for both line and load regulations.
Keywords: Switched Mode Power Supply (SMPS); Right-Half-Plane Zero (RHPZ); Sliding Mode Control (SMC); Transient Settling Time (TST); Transient Voltage Deviation (TVD);.
Conventional Inverter Emulation-Based DTC Strategy Dedicated to Delta Inverter
by Imen Nouira El Badsi, Bassem El Badsi
Abstract: The paper proposes a novel direct torque control (DTC) strategy for induction motor (IM) drives fed by (B3-VSI). The introduced strategy, noted DTC_Emu_
B3 , is based on the emulation of the operation of the conventional inverter (B6 VSI). The limitation associated with the reduced number of the intrinsic voltage vectors generated by the B3-VSI has been eradicated by suitable synthesis of the look-up table incorporated in the DTC scheme. A suitable combinations of the three voltage vectors intrinsically generated by the B3-VSI, lead to the synthesis of the six balanced voltage vectors of the B6-VSI. This approach has been adopted in the design of the look-up table of the proposed DTC strategy. Simulation and experimental results have revealed that B3-VSI fed IM drives exhibit interesting performance. These have been experimentally validated.
Keywords: Direct torque control; induction motor drive; conventional inverter;rnreduced structure inverter; emulation; look-up table.
Regulation of Hybrid Micro Grid Under Transient Operations
by Narayan Gupta, Priyanka Paliwal
Abstract: In recent times, there has been a significant awareness in the installation of distributed generation comprising of renewable energy resources such as wind and solar. As output available from solar or wind resources is not constant at all points of time. The proposed hybrid micro grid is seen as a promising solution to counteract the effect of intermittency of wind and solar radiations. This paper deals with voltage and frequency control in grid connected and islanding micro grid. In this paper, a hybrid AC/DC micro grid comprising of wind driven doubly fed induction generator (DFIG), solar photovoltaic system and solid oxide fuel cell (SOFC) along with a battery energy storage system interfaced with voltage-frequency controller is proposed. SOFC and Solar PV cell are connected to common DC bus; which is synchronized with AC bus at point of common coupling where wind generator and utility grid is connected. The voltage and frequency controller interconnected at PCC takes care of transients and ﬂuctuations which arise due to transition between islanding and grid connected mode, and presence of nonlinear loads. It also maintains bidirectional energy exchange among utility grid and micro grid. The proposed control algorithm is distributed in nature which overcomes the disadvantage of single point failure as in central controller; also it does not require any communication link which reduces the cost of controller. The proposed novel strategy suits well in sustaining voltage and frequency in islanded operation of micro grid due to any fault or disconnection of main utility grid, as well as in grid connected mode and in resynchronization with utility grid. The controller also maintains total harmonic distortion (THD) within specified norms under different balanced/unbalanced linear and non linear loading conditions. The SPS tool has employed to verify the efficacy of proposed topology.
Keywords: Micro Grid; Grid side converter; Rotor side converter; Solid Oxide Fuel Cell; Solar Photovoltaic cell; THD; Voltage Frequency (VF) Controller; Battery Energy Storage System (BESS).
Soft-Switched High Step-Up DC/DC Boost Converter for Distributed Generation
by Shib Sankar Saha
Abstract: Conventional boost converters are practically operated with maximum voltage gain of 5, as an extremely large duty cycle in excess of 80% results in reverse recovery problem of boost diode and large conduction losses in power devices, inductors and filter capacitors. High step-up boost converters, as required in distributed generation systems using green energy sources, are now-a-days drawing prime attention of power electronics engineers. In recent years, wide research is going on to operate the switching devices under soft-switched condition, so that, the converters can be made more compact by operating at high switching frequency and simultaneously maintaining high efficiency. In present work, a new soft-switched high step-up coupled-inductor boost converter is proposed to meet the demands of distributed generation systems. Performance of the proposed converter is verified by a prototype laboratory model and behaviour of the converter is found to confirm the theoretical analysis.
Keywords: Coupled inductor; DC-DC boost converter; High voltage gain; Pulse-width-modulation (PWM); resonant converter; soft-switching; switch mode power supply (SMPS); zero-current switching (ZCS); zero-voltage switching (ZVS).
Performance evaluation of 2.25 kWp rooftop Solar PV plant based on experimental measurements in the desert environment, Case study for Ghardaia, Algeria
by Layachi Zaghba, Messaouda Khennane, Amor Fezzani, Idriss Hadj Mahamed, Abdelhalim Borni
Abstract: The aim of the present study was to assess the electrical performance and the suitability of a of 2.25 kWp micromorphous photovoltaic plant in desert climate in the region. These PV plant were placed on the roof of a Car Parking in the field of Applied Research Unit in Renewable Energy (URAER) located at Ghardaia (latitude 32.37
Keywords: micro-amorphous; grid connected; solar PV rooftop; performance parameters; monitoring; desert environment.
Hybrid PWM modulated Cross Switched Asymmetrical Multilevel Inverter with Reduced Number of Conducting Devices
by Thamizharasan Sandirasegarane, Maalmarugan J, Krishnakumar C
Abstract: This paper brings out a new topology for a cascaded multilevel inverter (CMLI) with a view to reduce the number of power switching devices in the path of the current. The philosophy suggests the integration of a low voltage pulse width modulated (PWM) inverter along with a high voltage fundamental switching inverter to produce the specified number of output levels by switching the series connected dc sources of high voltage inverter in an additive and or subtractive combination with low voltage PWM inverter. It invites a hybrid PWM approach to the process of generating the pulses for synthesizing the stepped nature in conjunction with the variable pulse width output. The use of a smaller number of switches to reach the output voltage show cases the ability of the modular architecture to expand the scope of CMLI. The artifacts of a Field Programmable Gate Array (FPGA) foster to realize its implementation in pulse generation for switching the devices and verify the simulated results for steady state and dynamic load conditions in order to attach a viability perspective for its use in the real world.
Keywords: Field Programmable Gate Array; Pulse Width Modulation Inverters; Hybrid PWM; Reduced gate drivers.
Real-time performance evaluation of Two-Quadrant Z-Source DC-DC Converter for DC Drive
by Hanuman Prasad
Abstract: This paper contributes to real-time performance evaluation of two-quadrant z-source DC-DC converter drive for industrial application. Regulating the switching duty ratio of the converter produces the desired output voltage level. Z-source DC-DC converter has additional qualities over a traditional buck-boost converter such as higher boost factor at low switching duty ratio, more reliable, inherent short circuit protection and impedance network that behaves as a second-order filter. Z-source converter-fed separately excited DC-drive model is developed in MATLAB/Simulink and executed in field programmable gate array (FPGA)-based real-time digital simulator (RTDS) at fixed-time step of 10
Keywords: FPGA; RTDS; z-source DC-DC converter; DC motor; switching duty ratio; PI controller; regenerative braking.
Elucidation for Prime Power Flow DelinPuent in Wind Energy System
by Nagalashmi P.
Abstract: Wind energy is a renewable energy source its generation rate is tends to be due to uncertainty. This issue (OPF) is considered to resolve by a replacement Amalgam Multi Destination Synthetic Physical Optimization (AMDSPO) algorithmic rule, which does not require any administration parameters contrasted with various meta-heuristic calculations. Synthetic Physical Optimization (SPO), a modestly new population based intelligence algorithm, indicates fine execution on change issues. Besides, this paper presents half breed assortment of Animal Trek Optimization (ATO) algorithmic govern to express the union normal for SPO.The proposed methodology effectiveness is tested on IEEE 30-bus,IEEE 118-bus and IEEE 300-bus check system. The results oriented in the proposed methodology are compared for its betterment from other techniques. Thus the proposed methodology resolves the OPF issue and gives efficient wind energy power generation system.
Keywords: Renewable energy sources; Optimal Power Flow (OPF); meta-heuristic Algorithms; Artificial Physical Optimization (APO); Animal Migration Optimization (AMO).
Amplifying Power Quality and Diminishing Harmonic Distortion in MG VIA Adaptive MPC Based Robust EKF through IPSO-SHE
by N.Narender Reddy, A. Srujana, O. Chandrashekar
Abstract: The objective of Micro Grid (MG) is to generate, regulate and distribute the electricity to the utility grid. Any faults occur in the MG can cause deviations on the voltage, frequency and voltage sag/ swell, which affects the power quality. In order to overcome these issues in this paper we proposed to design an Adaptive Model Predictive Control (MPC) based Robust Extended Kalman Filter (REKF) with Improved Particle Swarm Optimized Selective harmonic Elimination (IPSO-SHE) Control system. This fetches the importance of power quality improvement. The utilization of Adaptive MPC with Robust EKF express the harmonic signatures produced in the system which can be used to detect islanding. An IPSO-SHE is finally employed to reduce the harmonics which significantly improves the quality of power delivered to the load. Our proposed control system has been implemented in the working platform of MATLAB/SIMULINK and tested with certain load conditions. The simulation results of the proposed control system and comparison with existing control systems shows the significance of the proposed work.
Keywords: adaptive model predictive control extended Kalman filter (EKF); islanding; improved particle swarm optimization (IPSO); selective harmonic elimination (SHE).
A Novel Design and Control Strategy of DVR for Fault Current Mitigation
by Sheena Latif, Savier J.S
Abstract: This paper proposes an innovative topology and control algorithm of Dynamic Voltage Restorer (DVR) for limiting the fault current in a grid connected power system. The method takes into account the effect of both balanced and unbalanced fault conditions affecting sensitive loads. The DVR acts as a voltage restorer during voltage sag conditions and as a fault current limiter during fault conditions. The Fault Current Limiting (FCL) mode of DVR is analysed with two topologies, one with conventional crow bar switches and the other with Out of Phase DVR (OPDVR) in which an out of phase series voltage is injected into the grid. Analysis of the method is carried out in MATLAB/SIMULINK environment. The results obtained with the proposed method indicate that OPDVR has better performance as compared with the conventional FCLDVR mode of operation.
Keywords: Voltage sag; Dynamic Voltage Restorer; Fault Current Limiting; Out of Phase DVR; Fault Current Limiting DVR.
Non-Linear-Variable-Gain Fuzzy Control with Finite Control Set Model Predictive Based DSTATCOM System to Improve Power Quality in Distribution System
by Gokulananda Sahu, Kamalakanta Mahapatra
Abstract: In this paper a T-S (Takagi-Sugeno) fuzzy control structure with model predictive current control based distribution static compensator (DSTATCOM) is proposed to improve power quality in distribution system. This control technique is based on proposed instantaneous symmetrical component and active power (ISCAP) method for reference generation, T-S fuzzy control for quick stabilization of DC-link voltage to achieve faster tracking of reference currents and model predictive control for switching signals generation without need of modulators. This combined effort enhances the compensation capability of the system as well as making the system cost effective. Through simulation and real-time experimentation it is found that proposed controller has improved performance in terms of harmonic elimination, power factor correction, quick stabilization of DC-link voltage and reactive power compensation. Finally this controller is employed with real-time hardware-in-the-loop (HIL) based OPAL-RT 5600 System with RTDS hardware OP5142 which is incorporated with front end processor Xilinx spartan-3 XC3S5000.
Keywords: Distribution Static Compensator; Model Predictive Control (MPC); Power quality; Real-time Digital Simulator(RTDS); Hardware in-the-loop(HIL); Fuzzy Logic Control(FLC).
Modeling and Simulation of Three Phase Power Factor Correctors with Fast Dynamic Response based on Fixed PWM and Bang-Bang control Techniques using DC-DC SEPIC Converter Modules
by Umamaheswari M G, Sivasubramanian S, Sam Swamya Vasanth, Lekshmi Sree B, Veerapandiyan Veerasamy
Abstract: The main concerns of the power supply industry is to obtain a single stage converter with a low-cost for achieving Power Factor Correction (PFC) complying with required harmonic standards and regulated output voltage simultaneously, especially for high power three-phase applications.This paper presents the modeling and simulation of single stage Three Phase Power Factor Correctors using DC-DC SEPIC converter modules based on Fixed PWM/ Bang-Bang control techniques. The design equations and state space model of the DC-DC SEPIC converter to aid the control loop are derived based on the modes of operation of converter. The cascade control strategy uses single outer voltage loop using Proportional Integral (PI) controller to regulate the output voltage and three inner Fixed PWM/ Bang-Bang controllers to shape the source current. PI controller parameters are determined by using TYREUS-LUYBEN tuning method. Extensive simulation studies are carried out by using MATLAB/ SIMULINK software tool. Performance analysis has been made for the two proposed approaches by comparing the simulation results.It is inferred from the results, the proposed scheme provides the power factor close to unity, low % Total Harmonic Distortion (THD), regulated output voltage for load variations and effective set point tracking. To substantiate the simulation results, experimental results using fixed PWM technique is presented.
Keywords: Power Factor Correction (PFC); Cascade control; Fixed PWM control technique; Bang-Bang Control; Proportional Integral control; Pulse Width Modulation (PWM); Switched Mode Power Supply (SMPS); Total Harmonic Distortion (THD).
A Novel Maximum Power Point Tracking Technique Based on Extreme Value Theorem for Photovoltaic Systems
by VANDANA JHA, UDAY SHANKAR TRIAR
Abstract: This paper proposes a new maximum power point tracking method for photovoltaic devices based on Extreme Value Theorem. The proposed method is based on the property that if a real-valued function is continuous in the closed and bounded interval, then it must attain an absolute maximum and an absolute minimum, each at least once. A critical point is an interior point in the domain of a function at which the derivative of the function with respect to the concerned variable is equal to zero or derivative of the function does not exist. In the proposed technique, applying the Extreme Value Theorem, the derivative of the power with respect to the voltage of the photovoltaic device is equated to zero and subsequently the exact value of the voltage of the photovoltaic device at the maximum power point is obtained without any iteration.
Keywords: Photovoltaic systems;Maximum power point tracking;Extreme Value Theorem;Critical point;Derivative.
Hybrid ANFIS-FA based control strategy for UPQC -Power Quality enhancement in Smart Grid
by P. Malleswara Reddy, A. Srinvasula Reddy, B. Sarvesh
Abstract: In the paper, a hybrid technique is proposed for analyzing and controlling PQ issues in SG. Initially, the normal behavior of SG system is analyzed. After that, some disturbance is created in the SG system and determined the abnormal behaviors. First phase of proposed methodology is utilization of wavelet transformation algorithms for processing the inputs. Here, Multi Wavelet Transform (MWT) is utilized to extract the features of inputs for classification. The hybrid technique is a combination of hybrid ANFIS and FA, which is utilized to maintain the dc-link voltage of the UPQC. The hybrid ANFIS means, FA is used to select the optimal dataset for training the ANFIS. The main objective of the proposed technique is detecting and controlling the PQ issues in SG. The proposed method is implemented in MATLAB/Simulink platform. In order to analyze the effectiveness of the proposed method, various types of issues are analyzed and tested with the existing methods such as, UPQC with ANFIS, UPQC with Artificial Neural Network (ANN) technique, UPQC with Gravitational Search Algorithm (GSA).
Keywords: Adaptive Neuro Fuzzy Inference System (ANFIS); Firefly Algorithm (FA); Power Quality (PQ); Smart Grid (SG) and Unified Power Quality Controller (UPQC).
Single Phase Transformerless Photovoltaic Inverter for Grid Connected systems- An overview
by Mohammed Ali Khan, Ahteshamul Haque, V. S. Bharath Kurukuru, Saad Mekhilef
Abstract: Renewable energy sources plays a vital role in satisfying the growing electricity demand. Out of the numerous available sources solar energy is projected as the most viable ones. Solar Photo Voltaic is used for converting solar energy into unregulated DC electrical energy. The generated DC energy is converted to AC voltage of anticipated magnitude and frequency using solar inverters. Transformerless grid integrated inverter is the emerging topology used in the solar inverter. The objective of this paper is to provide a critical review of the grid integrated solar inverter. The review is done on the primary operation, research advancements in topologies & control, comparing performance parameters, listing challenges. In addition, a review of industrial solutions with performance parameter is also provided. Furthermore, review of various other important parameter was also presented. A new topology is proposed, and its performance is evaluated and compared with the simulation results of conventional topologies. The common mode noise is reduced in the new proposed topology.
Keywords: Solar Inverter; Transformerless Topology; Control techniques; Cost
Experimental Investigations on Three-Phase Interleaved SAPF with Modified Indirect Current Control Algorithm
by Vijayakumar Gali, Nitin Gupta, Ram Avtar Gupta
Abstract: This paper presents a novel inverter topology, called three-phase interleaved inverter for three-phase shunt active power filter (SAPF). This proposed topology is used for compensating current harmonics, reactive power to improve the power factor of the system. In addition, it eliminates the shoot-through problem which is the hazardous problem in conventional voltage source inverter (VSI based SAPF. This proposed topology uses reference current generation techniques to control the flow of compensating currents and reactive power. The existing feed forward control techniques results in switching notches and distortions in the reference source current hence, poor harmonic compensation. Modified indirect current control technique (MICC) is implemented in this paper to generate a reference current without distortions. Therefore, no switching notches and ripples presents in the source current hence, the source current %THD will be improved. The proposed system is modelled by using MATLAB
Keywords: Interleaved inverter; modified indirect current controller; shoot-through problem; switching notches; voltage source inverter.
Power Quality Improvement using Multilevel Inverter Based Active Filter for Medium-Voltage High-Power Distribution System: A Comprehensive Review
by Soumyadeep Ray, Nitin Gupta, Ram Avtar Gupta
Abstract: Medium-voltage distribution system faces great challenges as number of medium-voltage; high-power loads such as electric drives etc. are increasing which inject non-linearity into the grid. On the other side, sinusoidal and uninterrupted voltage and current waveform at rated frequency is highly desirable at low to high power consumer end. Voltage/ current harmonic content, poor power factor, reactive power burden, poor voltage regulation and excessive neutral current create major problem in balanced/unbalanced loading condition. In such cases, filters provide a viable solution to overcome the aforesaid power quality problems. Conventional two-level inverter based active power filter is becoming popular and cost effective solution due to its simple structure and easier control. However, this configuration is facing great challenges in medium-voltage distribution network due to use of high rating switching devices and use of line-frequency transformer. Multilevel inverter (MLI) posses a great solution in such scenario as it generates higher voltage output with lower rating switching devices. As a result, voltage and current of improved quality can be maintained using MLI which is based on lower rating semiconductor devices. MLI based filters are successfully used in medium-voltage distribution sector and a lot of research around the globe are already carried out in this area. However, capacitor voltage balancing is a major research domain in MLI based filters. Despite of this, MLI technology is widely accepted in medium to high-voltage industrial applications. Therefore, this paper presents a widespread review on MLI based active filter (AF) by assessing its potential to replace two-level inverter based AF in medium-voltage distribution sector. Different possible configurations, control techniques, selection of power semiconductor switches and their different applications are reviewed comprehensively. A list of 131 research papers is decisively examined and is appended for quick reference.
Keywords: Active filter; Multilevel Inverter; Power Quality; Control Technique.
An Adaptive Power System Management with DG Placement and Cluster Based Load Forecasting By CS, K-Means and ANN Algorithms.
by Veeresha A.G, Maruthi Prasanna H. A, Likith Kumar M. V., Ananthapadmanabha T.
Abstract: Power system management plays a big taskof grid utilization in the researcher‟s world with the maintenance of power imbalance by proper power distribution with load forecasting in the network. For better grid utilization, a distributed generation (DG) and load forecasting system must be integrated to get the reduced power loss.Concern to that placing of DGs is very important for maintaining the good voltage profile.Hence,the paper proposed a novel system for complete power system managementwith proper grid utilization based on DG placement and load forecasting using cuckoo search (CS) and K-mean with artificial neural network (ANN). The proposed system placed the DG in a most appropriate place by optimization subsequently predict the load by utilizing cluster based algorithm thereby reducing the power loss and maintain good voltage profile.The proposed system is tested in standard IEEE-30 distributed Bus system suggested that the performances analyzed based on power qualities as well as load forecasting provides better performance on power qualities with minimum power loss of 0.035kW and the good total voltage profile of 312kv.
Keywords: Distribution Generation (DG) placement; cuckoo search algorithm; artificial neural network; load forecasting; power grid utilization.
Enhancement of Fault Ride-Through Capability of Grid-Connected Wind Farm
by Kishor Bhadane
Abstract: The Distributed Power Generation (DPG) at low /medium voltage demands that the renewable generation system is always grid connected during fault condition to ensure the stability of wind power system. The DPG consisting of Wind Turbines (WT) along with Fixed Speed Induction Generator (FSIG) does not provide accurate reactive power control and hence there is need for dedicated compensation. Due to fault condition the negative sequence component is affected and hence there is direct impact on DPG with reduction in life expectancy. This paper proposes the application of Distributed Static Compensator (DSTATCOM) for Fault Ride through (FRT) and reactive power compensation. It has been observed that the compensation of negative sequence component improves the performance of FSIG based WT. Also the compensation of positive sequence component avoids the collapsing of voltage and improved the stability of WT. The simulation is done in MATLAB and various tests are considered under fault condition in which results are presented. The FRT enhancement of grid connected WT by usingrnDSTATCOM is 30% and hence 30% additional wind power is penetrated to the grid
Keywords: Distributed Power Generation; Wind Turbines; Fixed Speed Induction Generators; Fault Ride Through capability;rnDSTATCOM.
Analysis of Voltage Stress on a Coupled Inductor Based High Gain Boost DC-DC Converter with Light Load Condition
by Tanmoy Roy Choudhury, Byamakesh Nayak, Subhendu Bikash Santra
Abstract: In this paper, voltage stress of a coupled inductor based high gain boost DC-DC converter is established under light load condition. During this condition, reverse recovery occurs on the switches of the converter enabling resonance condition on the parasitic elements of the devices. Due to this, a large voltage stress appears on the switching devices. However, appropriate snubber design can save the devices from the attack of this voltage stress. To attain a proper snubber design, a complete realization of the parasitic elements has to be suitably evaluated through a complex and tedious analysis. However, an indirect method using maximum voltage stress analysis can also be a suitable alternative for proper snubber design. A detailed study in this regard with respect to steady state analysis, voltage stress formulations with a variation of load condition etc. are the key aspects of this work. Validation of this study is carried out with a laboratory prototype of 50 W capacity.
Keywords: coupled inductor; gain crossing point; light load condition; single switch; voltage stress on devices.
Decoupled Control of Quasi-Z Source Inverter for Decentralized Renewable Energy Application
by ARVIND YADAV, Vinay Deolia, Sanjay Agrawal
Abstract: Decentralized Renewable Energy (DRE) systems are acclaimed worldwide as it serves as an alternate to the grid extension to remote areas having no access to electricity. The Impedance Source Inverter (ZSI) has overcome the limitations of conventional Voltage Source Inverter (VSI), have buck/boost capabilities. This paper presents an alternative approach of obtaining shoot-through pulses in a quasi-Z source inverter (qZSI) along with decoupled control by keeping dc link voltage constant instead of capacitor voltage. Dynamics of the system are investigated by deriving small signal model, the proposed control methodology uses separate controllers to handle dc and ac side dynamics to get desired shoot-through pulse and modulation index without any overlap, performance of the control methodology is verified under normal condition and under disturbances. Results are obtained using PSIM which verifies the control methodology and depicts the ability of disturbance rejection and effective reference tracking without compromising stability issues.
Keywords: DRE system; Photovoltaic (PV) module; Quasi-z source inverter; shoot-through (ST); decoupled control.
Method of Calculating Generator in the Mode of Recuperative Braking in the Improved Start-Stop System
by Vladimir Dvadnenko, Shchasiana Arhun, Aleksandr Bogajevskiy, Svitlana Ponikarovska
Abstract: Improving the method of recuperative braking of a car with a start-stop system by installing an additional generator is offered. This generator is connected with driving wheels, which makes possible to increase the efficiency of a car with a start-stop system. The features of recuperative braking in the proposed start-stop system allow using the stored kinetic and potential energy of the car more efficiently. An option of the optimal control of the brake torque of an additional generator is offered. The recuperative braking under consideration required an appropriate method of calculation. This technique makes possible to obtain the dependence of the braking moment on the angular velocity of the generator in various modes, the dependence of the allowable maximum generator power on the speed and load, the dependence of efficiency and the braking moment on the speed. Redistribution of energy generated by an additional generator for charging the battery and heating the engine coolant has been introduced. The brake torque of the electric machine G290 is calculated in the mode of recuperative braking when the car is moving at a speed higher and lower than critical, as well as in the rheostatic braking mode. The obtained results are of practical importance for the transport industry.
Keywords: start-stop system; mathematical model of synchronous generator; recuperative braking; hybrid car; ecological safety; valve electric drive.
An Improved Low Switching Frequency Modulation Scheme for a Symmetric CCS-Multilevel Inverter
by Rakesh Kumar, Deepa Thangavelusamy
Abstract: In this paper, a low switching frequency modulation scheme is proposed for the symmetrical configuration of Cross Connected Sources based multilevel inverter (CCS-MLI). The proposed scheme, named modified Nearest Level Modulation (mNLM), is an improvement over the conventional Nearest Level Modulation (NLM) scheme for MLI. The implementation of mNLM, compared to the NLM, has shown a considerable reduction in total harmonic distortion (THD) at the ac output of MLI. The mNLM works through variations in the switching angles of the MLI. By suitably varying the switching angles, the THD content is brought to the minimal. An algorithm for the same is also proposed which enables the mNLM to be implemented on other MLI topologies. Simulation is carried out in MATLAB/Simulink environment and it is also extended to a hardware prototype. The effectiveness of the proposed modulation scheme is also seen in terms of improved inverter parameters such as rms voltage, rms current, generated power.
Keywords: Multilevel inverter; Pulse width modulation; Inverter modulation scheme; Total harmonic distortion; Nearest level modulation; Cross-connected sources based inverter.
A Novel Modeling and Control Strategy for a Full-wave ZCS Quasi Resonant Boost converter for PV-based Battery Charging System
by Reza Sabzehgar, Rami Ghali
Abstract: In this paper, a novel modeling and control strategy is proposed for a DC-DC quasi resonant boost converter utilized in a photovoltaic-based (PV-based) battery charging system. The MOSFET switch of the boost converter is operated at zero current using a resonant tank, providing soft-switching functionality, to reduce the switching losses experienced by conventional boost converters. The principles of operation of the utilized converter are analyzed in details and a characteristic function representing the model of quasi-resonant converter circuit is derived. This model is then used to design and implement a frequency control technique, which will maintain a constant DC voltage at the output stage of the converter to charge the battery. Simulation studies are conducted using Matlab Simscape toolbox to evaluate the performance of the proposed controller. Simulation results validate the soft-switching functionality of the converter and its ability to reach and maintain the desired output voltage for charging a battery load in the presence of varying input voltage generated by a PV system with intermittent nature.
Keywords: Soft Switching; Zero Current Switching (ZCS); Full-wave Quasi Resonant Converter; Boost Converter; Photo Voltaic (PV) System; Battery Charger; Control of Power Electronics Converter.
Effective Predictive Current Control for a Sensorless Five-Phase Induction Motor Drive
by Mahmoud MOHAMED
Abstract: The paper aims to develop an effective predictive current control (PCC) procedure for a sensorless five-phase induction motor (IM) drive. The proposed PCC considers the discrete behaviour of the voltage source inverter and provides the voltage vectors utilizing the finite control set (FCS) principle, thus there is no need for using the pulse width modulation (PWM) techniques. A combined sliding mode -Luenberger observer is used to estimate the motor speed, stator current, rotor flux, load torque, and stator and rotor resistances. An effective pole placement procedure is proposed for selecting the most appropriate gains of the observer to enhance the estimation process and to improve the observers robustness against uncertainties in the system. The drive performance has been tested for a wide range of speed changes. The obtained results demonstrate the effectiveness of proposed PCC in obtaining high dynamic performance from the drive. Moreover, the proposed sensorless procedure has confirmed its validity to estimate precisely the required control variables.
Keywords: Five-phase IM drive; predictive control; current control; sensorless control; sliding mode observer; Luenberger observer; pole placement.
Development of Generalized and Optimum Structures of a Multilevel Inverter using Switched Capacitor Technique for Renewable Energy Conversion Systems
by Tapas Roy, Neha Aarzoo, Abhijit Dasgupta
Abstract: A novel multilevel inverter topology is presented in this paper. The presented topology is based on the concept of switched capacitor technique. The important features of proposed topology are that it uses symmetrical DC power sources to generate different output voltage levels, it has self-voltage balancing capability to balance the capacitor voltages and it can boost the input voltages to desire voltage levels. Further, optimal structure of proposed topology is developed from general structure of presented topology. Proposed topology requires less components such as switching devices, DC power supplies, capacitors, diodes to generate specific number of output voltage levels in comparison with other topologies. Phase disposition pulse width modulation (PDPWM) scheme is employed for switching the proposed inverter. Extensive simulation and experimental studies of 17-level proposed inverter structure prove its merits and effectiveness. The proposed topology can be applied in renewable energy conversion systems such as photovoltaic systems to generate boosted multilevel output voltage from low voltage DC renewable sources.
Keywords: Boosting factor; multilevel inverter; switched Capacitors; voltage Level.
Response of Electron-irradiated Silicon Carbide Schottky Power Diodes at Elevated Temperature
by Nurul Fadzlin Hasbullah, Mohamad Azim Mohd Khairi, Yusof Abdullah
Abstract: Thermal dependence experiments have been carried out on silicon carbide Schottky power diodes. The devices were exposed to 3 MeV electrons with 10 MGy dose. Current density-voltage (~300 K to ~490 K) characterization have been used for the investigation. The results show that, at the highest tested temperature, the forward current density at 0.3 V increased approximately 7 orders of magnitude for unirradiated devices and approximately 8 orders of magnitude for the irradiated devices. The increase is believed due to the generation of free carriers which obtained the energy from the temperature. The series resistance of unirradiated increased with increasing temperature which may be due to the decrease in the free carrier mobility, whilst the series resistance of irradiated devices decreased with increasing temperature which indicates that more free carriers have acquired enough energy to be released from the traps introduced by the irradiation. The reverse current density shows that the current increased with increasing temperature due to the radiation-induced defects that act as generation-recombination centres. The activation energies of the irradiated devices were derived, and it is higher than the unirradiated devices. On top of that, there are two slopes in the plot of the activation energy versus voltage which suggests that the reverse leakage current is probably due to two different type of mechanisms.
Keywords: electron radiation; SiC; Schottky diode; high voltage; temperature dependent; electrical characterization; activation energy; leakage current mechanism.
Bi-directional Power Flow Control with Improved Power Quality using Intelligent Controller for AC-DC Coupled Hybrid Micro-Grid System
by C. Nagaraj, K. Manjunatha Sharma
Abstract: At the level of the distribution system, the intermittent solar-wind renewable sources and non-linear power electronic loads connected to the mains grid causes harmonics, which distorts its current. Also, many DC loads are connected to the AC distribution system and thereby increases the power conversion stages. These issues can be adequately addressed by introducing the smart micro-grid system. In an individual AC or DC micro-grid, the more number of AC-DC-AC/DC-AC-DC power conversion stages lead to the losses. Therefore, in this paper, the AC-DC coupled hybrid micro-grid system is presented in which AC renewable sources and AC loads are connected to AC sub-grid as well as DC renewable sources, and DC loads are connected to DC sub-grid thereby reducing the power conversion stages. Further, the generalized power conversion loss calculation is also discussed. The shunt active power filter based 3ϕ 4-leg bi-directional intermediate converter using d-q load current technique without phase locked loop is proposed to achieve the inverter-based and rectifier-based power flow between AC and DC sub-grids with acceptable power quality as per IEEE 519 standards at a common coupling point. The hysteresis based current technique is used to compare the actual filter current with a reference filter current to generate the switching pulses for the bi-directional intermediate converter. The MATLAB simulation is carried out, and the performance of the proposed system is analyzed using the d-q load current technique based fuzzy logic and PI controller. To validate the proposed control technique, different case studies are performed by considering balanced and unbalanced grid and load conditions with variation in renewable sources. The obtained results demonstrate that the overall system performance is improved with the d-q load current technique based fuzzy logic controller.
Keywords: bidirectional intermediate converter; common coupling point; coupled hybrid micro-grid; hysteresis based current technique; shunt active power filter.
Comparative Study of FCS-MPC and PWM Control Techniques for Autonomous Four-Leg VSI
by Raef Aboelsaud, Alexander Garganeev, Ahmed Ibrahim
Abstract: Finite control set model predictive control (FCS-MPC) is considered as a new control technique in the power electronics fields which dont require modulation stage. The absence of modulation stage results in operating under variable switching frequency which can affect the harmonic distortion of the output signal, the switching losses, filters design, and so on. On the other hand, the linear controllers control the power converters with constant switching frequency by using modulators. In this paper, the overall performance of FCS-MPC is assessed by performing a comparative study with a linear controller based on scalar pulse width modulation (PWM). The control systems are applied on an autonomous 4-Leg voltage source inverter (VSI) with LC filter as part of an autonomous power supply system. The main purpose of the two control techniques is to control 4-Leg VSI to provide balanced load voltage with lower total harmonic distortion. The steady state performance of the two control techniques is tested under balanced, unbalanced, linear and nonlinear load conditions. Moreover, the effect of the load variations on the switching frequency of the FCS-MPC is discussed. Finally, the performances of the two control methods in tracking the reference voltage under transient conditions are analyzed.
Keywords: Control; FCS-MPC; PWM; PID; Four-Leg Inverter.
Droop Control Method based on Fuzzy Adaptive Virtual Resistance for DC Microgrids
by Hossein Khoramikia, Seyed Mohammad Dehghan, Saeed Hasanzadeh
Abstract: DC microgrid is a high-efficiency and high-reliability solution for integrating energy sources, energy storage units and loads. Droop control method based on the virtual resistance is the most popular control method for DC MGs. However, this method has two limitations: 1- Unequal load sharing in case of unequal line resistances of converters, 2- DC bus voltage deviation with increasing the load. In this paper, in order to solve these limitations, a new control method based on fuzzy controller is proposed to determine instantaneous virtual resistance considering current sharing error and DC bus voltage deviation. In the proposed method, a low bandwidth communication network is used for current sharing of converters and DC bus voltage regulation. The performance of the proposed method has been investigated for difference line resistances and load changes. The simulation results show that the proposed control method leads to increasing load sharing accuracy and DC bus voltage restoration improvement.
Keywords: DC microgrid; fuzzy controller; voltage restore; load sharing.
Model Predictive Current Control with Duty Ratio Optimization for a Three-phase Grid-Tied Inverter based on Runge-Kutta Approximation
by Shahrouz Ebrahimpanah, Qihong Chen, Liyan Zhang
Abstract: This paper proposes a model predictive current control for a three-phase inverter connected to the grid by using a duty cycle optimization based on Runge-Kutta approximation. In this method each of 7 possible switching states are checked to find one that minimizes the cost function. It is a fact that the current ripples cannot decrease to a minimum value because there is only one voltage vector during one control period, thus the sampling frequency should be selected high for a sufficient performance. In order to find a solution to this problem, a duty ratio optimization technique based on Runge-Kutta approximation is introduced by using a non-zero and a zero voltage vector. Moreover, the duration of the two voltage vectors are selected according to the current error minimization. Simulation and experimental results verify that the proposed method obtains reduced current ripples and lower total harmonic distortions compared to the conventional method.
Keywords: model predictive current control; THD; total harmonic distortions; cost function; three phase-grid tied inverter.
Multi-function Control of Small-scaled Grid-connected PV Systems
by Esmaeil Zangeneh Bighash, Seyed Mohammad Sadeghzadeh, Esmaeil Ebrahimzadeh, Frede Blaabjerg
Abstract: One of the most important fields in distributions grid is the power quality issue. In this regards, voltage drop and harmonic distortions are two important challenges in the power quality. Some custom power devices like Resistive-Active Power Filter (R-APF), Dynamic Voltage Restorer (DVR), and The Static Synchronous Compensator (STATCOM) are used in order to fix these challenges. However, due to the high cost, these devices cannot be dispersed overall distribution grid. On the other hand, the installation capacity of the grid-connected small-scaled PV systems in distribution grids is remarkable. Therefore, the capacity of these systems can play an important role in distribution grids. By applying a proper control, these systems can, in addition to their energy source, be used as a harmonic and voltage compensators at the point of common coupling (PCC). This paper presents a multi-functions control scheme for small-scaled PV systems. In the presented approach, the control system, in addition to delivering the energy of the panels to the grid, will put the solar system in the harmonic and voltage compensation process at the PCC. Both the voltage and harmonic compensation strategies are implemented by on-line analyzing the PCC voltage. The structure in the proposed approach is a single-phase transformerless HERIC inverter with the LCL filter at the output. Finally, the results will be evaluated by MATLAB simulator and verified by experimental prototype.
Keywords: Resistive-Active Power Filter (R-APF); Active Power Filter (APF); Dynamic Voltage Restore (DVR); Static Synchronous Compensator (STATCOM); Photovoltaic (PV); Uninterruptible Power Supply (UPS); and Low-Voltage Ride-Through (LVRT).
A Comprehensive Review on BLDC Motor and Its Control Techniques
by Dileep Kumar, R.A. Gupta
Abstract: Brushless direct current (BLDC) motor drives have gained more popularity and emerged as the latest research area due to their ability to offer salient features such as compact size, higher efficiency, less maintenance, rugged operation, more reliable, and high torque to weight ratio. Recently, BLDC motor drives are widely adopted in numerous fields of industries and household applications such as robotics, electric vehicle, defense, aviation, industry, ventilation, dryer, and air conditioner. Most of the BLDC motors are consist of three hall sensors which are commonly employed for generating the gate pulses for the inverter to achieve a successful commutation sequence. It is worth mentioning that, proper commutation sequence is essential in order to effectively control the phase winding current. Moreover, rectangular shaped phase currents are required to produce a constant torque. However, practically ideal rectangular current shape cannot be obtained due to the phase winding inductance. Therefore, BLDC motor drives are facing the great challenge of current ripples due to the unequal rate of incoming and outgoing phase current during the commutation process which results in torque ripples. In view of these aspects, this paper presents a comprehensive review of the BLDC motor drive. Different converter topologies and current/torque control techniques have been carried out thoroughly to verify the potential of BLDC motor drives.
Keywords: BLDC motor; Inverter; DC-DC Converter; Torque ripple; Current ripple.
Universal Inverters for Flexible Power Electronic Test-Bed Implementation
by Lei Shao, Hanze Liu, Jiucang Sun, Ji Li, Hongli Liu, Xiaoqi Chen
Abstract: As the rapid development of electric grids, power electronic equipment has been widely deployed in modern power systems. The flexible operation of power electronic equipment has significantly complicated the grid operation, which enables different types of grid operation conditions that need to be emulated in the lab to facilitate the testing and development of advanced control diagram. Note that the fully controllable power electronic converters make it feasible to establish and simulate different operation conditions, which greatly diversifies the flexibility of conventional test-beds used for power electronics and power system research. In this paper, a generic three-leg converter is used and further functional expansion is implemented to make it a controllable unit for simulating different grid assets, including photovoltaics (PVs), batteries, etc. Hence, a universal inverter-based grid simulator is developed. Advanced control diagram is designed to achieve the flexible operation of the power-electronics-based grid simulators. Rather than relying on conventional synchronous-frame-based proportional-integral (PI) controllers, proportional-resonant (PR) controllers in stationary frame is used to avoid the coordinate transformation from a-b-c framework to d-q-0 framework. In other words, the coordinate transformation from stationary frame to rotational frame is eliminated. Test cases are established to test and validate the developed universal grid simulator.
Keywords: Grid simulator; stationary frame; synchronous frame; universal inverters.
Design of a Model Predictive Controller for Grid Connected Microgrids
by Sambit Kumar Panda, Arnab Ghosh
Abstract: Power electronics converter and inverter systems for microgrid operations are always stochastic in nature. When the system operates in grid tied mode the user always faces a steady state residual problem as the load connected to the grid varies and so the amount of current drawn from the microgrid varies which leads to a mismatch between the actual current and desired current. As a result, input current changes which creates a significant amount of voltage drop at the input. All the converters and inverters used in our system are controlled using Model Predictive Controller (MPC) except the boost converter for solar PV system which is operating in Incremental Conductance method (INC) and for the bi-directional converter a two loop continuous current control is implemented for controlling the output voltage as well as the inductor current reference. The inner loop forms the core of MPC whereas the outer loop keeps track of the voltage. The proposed control strategy gives very fast dynamics when subjected to different stochastic conditions and certainly the control strategy doesnt allow the DC voltage to fall below a certain voltage level. Presented simulation results justify the effectiveness of proposed strategy.
Keywords: Microgrids; Model Predictive Control (MPC); Incremental Conductance method (INC); Optimization technique; Microparks.
Simulation and Comparative Analysis of Single Phase H Bridge Micro Inverters with Conventional PI Control and Virtual Output Impedance Control: A Case Study
by Apoorva Saxena, Durg Singh Chauhan
Abstract: In this paper it has been proposed that Microgrids can form economical and technically viable option for the electrification in remote rural areas. It has been observed that inverters form the basic building blocks of these Micro grids. Proper selection of inverter design parameters along with suitable gain margins and phase margins of control loops, can help in the stable operation of inverters with improved voltage quality by reducing the Total Harmonic Distortion (THD). The dual voltage and current feedback loops are designed for the proposed inverter and closed loop performance analysis is performed for the corresponding transfer functions. The effect of voltage and current loop control parameters on the phase margin, cutoff frequency etc is analyzed in detail using industry recognized PSIM software. Introduction of a third virtual capacitive feedback loop changes the inverter output impedance nature and magnitude. The design of this virtual feedback loop is explained by controlling the time constant of the integrator circuit. The comparative analysis of the inverter performance is done for both with and without the virtual impedance feedback loop through a case study of 510 W, 220 V system. It has been observed that introduction of capacitive feedback loop can lead to reduction in higher order voltage harmonics, improvement in voltage regulation etc.
Keywords: Microgrid; Rural electrification; Inverter; Dual feedback loop; Virtual impedance loop; Inverter output impedance.
Constrained Discrete Mode Control of supercapacitor energy storage system for improved AGC of a multi-area power system with effects of wind power
by Sabah Un Nisa, Mairaj Ud Din Mufti
Abstract: For successful integration of renewables with the existing power systems, energy stor- age systems are increasingly being used. This paper proposes the development of a discrete mode control strategy for integrating a small rating supercapacitor energy storage(SCS) into a wind embedded multi-area power system for cost effective and improved AGC. Global optimization toolbox(MATLAB) is used to make the primary control loop of SCS to mimic a first order lag relation. This is purposely done for achieving a dual objec- tive. On one hand SCS is being forced to follow faithfully the command from the master controller and on the other hand discrete version of the representative model of inner con- trol loop is utilized for a control design procedure which while considerably reducing the frequency and tie-power deviations, ensures constrained operation of SCS. To virtually validate the proposed scheme, relevant modeling issues are addressed and a simulation platform is developed in MATLAB/Simulink environment.
Keywords: Automatic Generation control,Wind Energy; Energy Storage System,Controller Design; Power System.
Active power filter using a novel adaptive fuzzy hysteresis current controller
by P. Karuppanan
Abstract: This paper presents a shunt active power filter (APF) for mitigating harmonics and reactive-power compensation in the distribution system. The compensation process is based on modified-synchronous reference frame (modified-SRF) control strategy that is different from conventional-SRF method. A simple and efficient unit vector calculation is used in the proposed modified-SRF in lieu of phase locked loop for vector orientation that cancels the presence of harmonics and notches in the distribution system. The shunt active power filter is implemented with voltage source inverter (VSI) and its switching pulses are generated through a novel adaptive-fuzzy-hysteresis current controller (HCC). The adaptive-fuzzy-HCC calculates the hysteresis bandwidth effectively with the help of fuzzy logic controller (FLC). This method reduces the switching power losses and improves the VSI performances for active filter substantially compared to fixed-HCC and adaptive-HCC. The shunt active filter system is validated through extensive simulation under both steady-state and transient conditions with different nonlinear loads. Comparative assessments of conventional-SRF and modified-SRF reference current generator methods are carried out.
Keywords: modified-synchronous reference frame; active power filters; APF; adaptive-fuzzy-hysteresis current controller; harmonics.
Line frequency sine modulation: a novel modulation scheme for multilevel inverters and its application towards enhanced illumination of incandescent bulb
by A. Rakesh Kumar, T. Deepa
Abstract: Several modulation schemes are proposed and implemented in multilevel inverters (MLIs) to reduce the total harmonic distortion (THD) content at its output. This paper proposes a new approach towards employing an fundamental switching frequency (FSF) modulation scheme to reduce the THD at the output of an MLI. It involves designing two matrices coined as inverter switching characteristics (ISC) matrix and inverter operating modes (IOM) matrix. The switching frequency depends on the line frequency of the MLI output. The presented modulation scheme is implemented in an asymmetrical topology MLI. An experimental setup is also carried for a maximum power rating of 200W. The experimental results show the proposed modulation scheme has improved the parameters of the inverters in terms of the output voltage, output current, THD content of voltage and current waveforms, output power and power factor. Thus the presented modulation control scheme has improved the performance of the inverter.
Keywords: MLI; multilevel inverter; topologies; modulation techniques; THD; total harmonic distortion.
A simplified and generalised SVPWM method including over modulation zone for seven level diode clamped inverter - FPGA implementation
by B. Sirisha, P. Satish Kumar
Abstract: This paper presents simplified and generalised SVPWM technique for a neutral point clamped multilevel inverter of any level. This modulation technique provides a simplistic strategy for transition between various modulation indexes with linear transfer characteristic which provides a general solution for over modulation zone. The proposed technique is based on 60° coordinate system with all the computational work is carried out online, generating the desired switching states and their sequences through simplified expressions without any additional storage requirement. This modulation technique combines the concept of reference vector modification and on duration modification during over modulation zones. The performance of the proposed technique is tested through FPGA spartan3A processor experimentally for seven level diode clamped inverter. The simulation and experimental results are validated at various modulation indexes and are in well agreement with each other.
Keywords: FPGA; SVPWM; neutral point clamped inverter; modulation index.
Design and implementation of a speed adaptive flux observer for the induction motor using Sylvester criterion
by Mihai Comanescu
Abstract: The paper presents the design and implementation of a flux and speed observer for the induction motor drive. The method employs an observer with linear feedback that yields the motor fluxes and also estimates the speed using an adaptive law. The convergence conditions are formulated based on Lyapunov's nonlinear stability theory. The gains of the observer are designed using Sylvester criterion. The method proposed is reasonably simple and yields a series of inequalities that provide insight into the design choices and stability margins of the observer. The paper shows that the observer is not globally stable - however, with proper design of the adaptation gains, it can be made locally stable. The observer with the corresponding adaptive speed estimate does not perform during low speed regeneration - the speed estimate diverges; to solve this issue, the paper shows a modified adaptation law that yields a stable speed estimate.
Keywords: induction motor control; flux estimation; speed estimation; rotor position estimation; Lyapunov stability theory; adaptive control; sensorless control.
Neural network-based three-phase NPC rectifier for DC bus capacitor voltage balancing under perturbed mains supply conditions
by Deepak Sharma, Abdul Hamid Bhat, Aijaz Ahmad
Abstract: This paper presents an artificial neural network-based modified space vector pulse width modulation control approach for better performance of three-phase neutral-point clamped rectifier using optimised switching sequences. Use of optimised switching sequences even under ideal supply conditions, it is depicted that source side and load side parameters deviate from acceptable limits and a DC-bus capacitor voltage unbalance occurs. Under the influence of disturbed supply, source side and load side parameters deviate more beyond acceptable limits which causes a very large unbalance in DC bus capacitor voltages. This non-ideal performance of the converter is responsible for the deterioration of quality of source currents and a large stress on power semiconductor devices. The proposed control scheme employs a three-layer feed-forward neural network at different stages for capacitor voltage balancing of a three-phase three-level neutral-point clamped converter with improved power quality. According to the supply conditions, the neural network varies the speed of the reference vector and forms a required trajectory while passing through the most effective regions of SVPWM hexagon. The proposed controller scheme is modelled in MATLAB/Simulink software. Simulation results show that the proposed implementation of neural-networks controller in three-phase NPC converter displays better performance under ideal and disturbed mains conditions.
Keywords: power quality; improved power quality converters; IPQCs; multilevel converters; harmonics compensation; unbalanced AC mains; disturbed AC mains.
Analysis of 4H-SiC Schottky barrier diode with a comb-shaped field plate
by Dongwoo Bae, Chungbu Jeong, Taewan Kim, Kwangsoo Kim
Abstract: In this study, we have proposed a comb-shaped field plate for use in a 4H-SiC Schottky barrier diode; this field plate was expected to improve the electric field distribution in the device and provide a higher breakdown voltage than conventional field plate structures. The main principle of the proposed structure is to distribute the inner electric field in the blocking mode through a stepped oxide structure formed by several trenches. The proposed structure was optimised using a simulation, and we fabricated and measured a number of devices to evaluate the performance of the proposed structure. The proposed device's breakdown voltage was 39% better than that of a SiC Schottky barrier diode containing conventional field plates.
Keywords: 4H-SiC; wide band gap; power device; trench oxide; edge termination; field plate; FP; electric field crowding; electric field distribution; breakdown voltage; impact ionisation.