International Journal of Power Electronics (39 papers in press)
Comparative Analysis of Unit Template, SRF and the Modified SRF Technique for DSTATCOM Based Distribution System
by Aaqib Ahmad Qureshi, Abdul Hamid Bhat
Abstract: This paper introduces a new hybrid control strategy called the Modified SRF theory which makes use of both SRF as well as unit template technique to generate the reference supply currents which are then compared with the sensed supply currents and fed to the hysteresis/PWM current controller to generate the necessary switching signals for switches of the VSC of the DSTATCOM for a three-phase three-wire system.. This proposed control algorithm is compared with the unit template or PI controller-based algorithm and the SRF theory to mitigate a variety of problems such as low power factor, voltage regulation, current unbalance and harmonics in the system. The proposed algorithm is proved better than conventional algorithms reported in the literature.
Keywords: DSTATCOM; control technique; power quality; unit template; SRF; Modified SRF; custom power device.
An improved grid integration technique for SPV based CHB-MLI in distribution network
by Prabir Ranjan Kasari, Subhadeep Bhattacharjee
Abstract: The growing power electronics based nonlinear load increases harmonic contribution in the power system that leads to deterioration in the quality of power. The unbalance loading in three phase four wire (3P4W) system allows a neutral current flow which is an escalating concern for the utility. In this paper, the instantaneous power balance method is employed for Solar Photovoltaic (SPV) based nine-level Cascaded H-Bridge Multilevel Inverter (CHB-MLI). A modified instantaneous Power Balance Method (PBT) is proposed for integrating this SPV based CHB-MLI. The average and oscillating zero sequence power are incorporated in the proposed instantaneous power balance method to generate an appropriate reference for interfaced CHB-MLI. It is evident from the study that, the zero sequence components have a significant effect on an unbalance three phase four wire system, considered as a utility in this paper. The proposed controller provides CHB-MLI that feeds the average power of SPV and also supports the utility by supplying nonlinear, oscillating power. This SPV based CHB-MLI is called Solar Photovoltaic Shunt Active Power Filter (SPV-SAPF). Further, the modular structure of this CHB-MLI facilitates the integration of large energy using low rated converter components. FFT analysis done for different voltage levels of CHB-MLI shows that Total Harmonic Distortion (THD) is within a permissible limit. Besides, simulation, experimental results are also provided to validate the performance of the proposed scheme.
Keywords: Active and reactive power; cascaded H-bridge multilevel inverter (CHB-MLI); harmonics compensation; instantaneous power balance theory.
Versatile Current Controller Suitable for Two-Level As Well As Three-Level Converters of Shunt Active Power Filters: Part-I
by Siddharthsingh K. Chauhan, Dr. P. N. Tekwani
Abstract: Current control strategy adopted, dominantly governs performance of shunt active power filter (SAPF). A versatile current error space phasor based hysteresis controller for SAPF is presented. The controller keeps the current error space phasor within prescribed hexagon shaped boundary by selecting appropriate voltage vector of SAPF. Switching of optimal voltage vector is ensured unlike non-optomum selection in conventional hysteresis controllers used for SAPFs. Proposed SAPF generates compensating currents effectively by cocordinaing sector change overs and supply frequency. Two different schemes for sector change detection are presented. The concept is simulated, and digital signal processor (DSP) TMS320LF2407A is used to implement the proposed controller. Experimental results depicting steady state as well as transient performance of the controller are presented. Effect of variation in hysteresis band on performance of SAPF is also reported. Adequate compensation provided by the SAPF for harmonic mitigation is evident from simulation and experimental results. However, complex voltage space phasor structure of multi-level converter puts limitation on proposed controller to detect sector changes. Application of proposed controller to multi-level converter based SAPF requires development of a versatile controller. Such a controller having capability to identify sector change in multi-level converters using outer hysteresis band is described in Part-II of this paper.
Keywords: Current Error Space Phasor; Hexagonal Boundary; Multi-Level Converter; Sector Change Detection; Shunt Active Power Filters; Versatile Hysteresis Current Controller.
Model Reference Adaptive System Based Precise Online Inertia Identification of Induction Motor with Error Utilization Technique
by Jay D. Mistry, Dr. P. N. Tekwani, Chirag Raval, Vinod Patel
Abstract: Time varying parameters can be estimated using either adaptive control or robust control. Robust control can be used only when the control law is fixed and varying parameters are bounded. Adaptive control is concerned with control law changing itself. Model Reference Adaptive System (MRAS) is an adaptive control method that can be used to identify initially unknown parameters. Variation in load and machine vibrations affect the control system performance of any motor drive system when it is in operating condition. Estimation of moment of inertia becomes essential to improve the dynamic response characteristics of any high-performance Asynchronous Machine (ASM) drive system. A novel method using Model Reference Adaptive System (MRAS) with Error Utilization Technique (EUT) for precise identification of online varying inertia is presented in this article. The proposed method uses an interesting relation between the estimation error and actual inertia, to compensate for the error and provide high precision online inertia identification.
Keywords: Asynchronous Machine (ASM); Model Reference Adaptive System (MRAS); Error Utilization Technique (EUT); Inertia Identification.
Versatile Current Controller Suitable for Two-Level As Well As Three-Level Converters of Shunt Active Power Filters: Part-II
by Siddharthsingh K. Chauhan, Dr. P. N. Tekwani
Abstract: Current controller presented in Part-I of this paper suffers from limitation in sector change detection for multi-level converter based power filters because of inherent complex voltage space phasor structure. A self-adaptive current error space phasor based hysteresis controller is presented that does not require calculation of voltage vector at point of common coupling for identifying sector changes. It requires one more hysteresis band placed little outside the main hysteresis band used for selection of voltage vectors. Sector change detection is executed only from the movement of current error space phasor and state of comparators on outer band. This versatile technique of sector change detection is equally applicable for two-level as well as three-level converter based power filter. Feature of adjacent voltage vectors switching is retained in the presented controller. Inherent problem of capacitor voltage imbalance is eliminated by effective use of switching state redundancy of three-level flying capacitor converter employed for power filter. Performance of controller is verified for two-level and three-level filter through thorough simulation studies. The controller is then implemented using DSP TMS320LF2407A for two-level filter. Adequate compensation provided by the controller in steady state, during transients and for variation in hysteresis band is evident through presented results.
Keywords: Current Error Space Phasor; Flying Capacitor Type Three-Level Converter; Self-Adaptive Sector Change Detection Technique; Shunt Active Power Filters; Two Hexagonal Boundaries; Versatile Hysteresis Current Controller.
An MRAS based Smoothed Kalman Observer for Speed Sensorless Indirect Vector Controlled Induction Motor Drives
by Uma Syamkumar, Jayanand B.
Abstract: This paper proposes a modified Kalman filter algorithm based on fixed-lag smoothing which can be used to estimate the rotor speed and flux of three phase induction motor. The behavior of a typical extended Kalman filter(EKF) algorithm is influenced by the process and measurement error covariance matrices. In EKF, these matrices are chosen by trial and error method and have to be varied according to the varying operating conditions of the motor. In this paper a smoothing based extended Kalman filter(SKF) algorithm which uses additional data points for estimation is proposed. Since additional data is used, the algorithm is able to give a better estimate, for same values of covariance matrices. The performance of the proposed algorithm is explored for sensorless indirect vector control application of three-phase induction motor. Finally, in order to validate the superiority of this algorithm, it is compared with the performance of EKF algorithm for various reference speeds in real-time. rnrnrn
Keywords: Sensorless Control; Smoothing; Observer; Extended Kalman filter; Three-phase induction motor.
Exploration of Bifurcation and Inherent Oscillation in a Current
Mode Controlled Cuk Converter - Effects of Turn-On and
Turn-Off Switching Delays
by Sukanya Parui, B. Basak
Abstract: The nonlinear phenomena in a dc-dc current mode controlled C'uk converter circuit has been explored. In reality, as any switching process is associated with turn-on and turn- off delays, the simulation has been extended considering these delays. The circuit exhibits a LC oscillation which may make the switch current oscillatory and in some cases the conclusion obtained from the bifurcation diagram regarding the dynamics of the system becomes incorrect. A mathematical expression for the oscillation frequency has been presented. A prototype ofrnthe converter has been developed. The simulated results have been verified experimentally.
Keywords: Bifurcation; Chaos; C'uk Converter; Oscillation.
SVM based Current Ripple Reduction with Two Parallel Interleaved Inverters for Induction Motor Drive
by RANVIR KAUR, Gursewak Singh Brar, Maninder Kaur
Abstract: Extensive research has been ongoing in the field of inverter fed induction motor drives. The main challenge in designing Pulse Width Modulation (PWM) fed induction motor drives is to reduce Total Harmonic Distortion (THD) and ripple content in ac output of inverter. The PWM method ensures the voltage balancing between two Parallel Interleaved Inverter (PII) inverters for each switching cycle. The PII includes two parallel units of two level three-phase PWM full bridge having multiple carrier waves with phase rotation analysed as single unit of three level inverter. PII improves the performance of drive while employing Space Vector Modulation (SVM) by reducing THD content by 14% for low modulation indices and improves up to 40% at high modulation indices. Ripple content is significantly reduced in line current for PII. Simulation and experimental results for PII for 5 hp induction motor are presented in this paper to validate low ripple current at output.
Keywords: PWM; three phase full bridge; SVM; parallel inverters; ripple content; induction motor.
New Approach of SOC Estimation Method for lithium-ion battery/Ultra-capacity Hybrid system Based on Multi-Model Strategy
by Qiuting Wang, We Qi
Abstract: The model precision of the lithium-ion battery and the computational complexity of state estimation procedure will not be satisfied at the same time. A new State of Charge(SOC) estimation method based on multi-model strategy (MMS) is proposed to ensure both the estimation accuracy and the real-time performance. Meanwhile, new modelling method and SOC estimation method for the battery energy storage system are presented. The main efforts of our work are, firstly, the hybrid system model is established based on multi-model strategy. Secondly, the model parameters are updated using extended Kalman filter(EKF) algorithm. Thirdly, the electric quantity of lithium-ion battery is estimated using Unscented Kalman filter(UKF) algorithm. The experiments were conducted under dynamic working condition and the NEDC working condition. The results indicate that the SOC estimation accuracy based on MMS is better than that without the strategy.
Keywords: lithium-ion battery; SOC estimation; multi-model strategy; Joint Kalman filtering algorithm; NEDC.
Phase locked loop Parameterization in AC/DC Interconnected System for a multi-source AGC system under Open market Environment
by Debdeep Saha, Lalit Chandra Saikia
Abstract: This article emphasizes on deregulated AGC of a realistic multi-machine gas thermal plant with dish-Stirling solar-thermal (DSTS) as additional power generation sources in each control Area by taking into accounts of AC/DC with phase locked loop dynamics (PLL). Eigenvalue analysis confirms the steadiness of the reasonable power system with various interconnections such as AC, AC/DC link and AC/DC with PLL dynamics. A series form of proportional-integral-derivative (PID) namely proportional gain cascaded with integral and double-derivative (PI+DD+) controller is employed as secondary controller in each control areas for robust AGC to carry out market transactions under deregulated environment. Exploring the system with different type of interconnections infer that proper tuning of PLL function parameters may synchronize the grid better than without employing PLL. The performance of PI+DD+ controller along with optimum PLL gains commensurate with wide variations in governor, turbine, fuel and compressor discharge time constant of gas turbine plant.
Keywords: Automatic generation control ; dish-Stirling solar thermal ; deregulated ; Eigen value; phase locked loop; series controller.
Development and Implementation of a Voltage Harmonic Elimination Method for the Single-Phase Inverter Operating with Nonlinear Load
by Bogdan Proca, Mihai Comanescu
Abstract: Single-phase inverters are widely used in power conversion systems. When operating with linear loads, these inverters produce regulated output voltages that are quasi-sinusoidal. However, when feeding nonlinear loads, these absorb currents that are non-sinusoidal (distorted) and the inverters output voltage deteriorates it contains high levels of harmonics. This paper presents a control method that reduces the harmonic content of the output voltage and improves the total harmonic distortion (THD). The control strategy is based on selective harmonic elimination the method eliminates some of the low order harmonics of the output voltage using feedback. The proposed method reduces the distortion in the output voltage and improves the voltage THD. The method uses a voltage controller followed by a current controller both are implemented in the stationary reference frame. The voltage controller regulates the fundamental and eliminates certain harmonics using a modulation-demodulation technique. In the paper, the 3rd, 5th and 7th harmonics are eliminated. However, the scheme can be expanded to eliminate more higher-order harmonics. It is shown that the control proposed significantly reduces the Total Harmonic Distortion (THD) of the inverters output voltage, from 5.8% (at full load, uncompensated) to 1.64% (at full load, with compensation). The method proposed is directly applicable for industrial single-phase inverters and is validated by simulations and experimental tests.
Keywords: single-phase inverter; total harmonic distortion; harmonic elimination; sliding mode current control.
Performance Investigation of a Transistor Clamped H-Bridge Inverter Based Dynamic Voltage Restorer for Mitigating Various Power Quality Problems.
by Humeera Altaf, Abdul Hamid Bhat
Abstract: This paper presents design and analysis of dynamic voltage restorer (DVR) employing five-level Transistor Clamped H-Bridge (TCHB) inverter that increases the applicability of DVR to medium voltage networks. TCHB inverter is a newly developed topology of multilevel inverters (MLIs) which uses lesser number of components as compared to other topologies. Synchronous Reference Frame Theory (SRFT) based control algorithm is used for implementation of proposed DVR. The compensation capability of proposed DVR is tested for various voltage related power quality problems like sag, swell, harmonics, imbalance and their combinations through MATLAB/Simulink software and the simulation results are verified experimentally by using Digital Real Time Simulator.
Keywords: Dynamic Voltage Restorer (DVR); Multilevel inverter (MLI);Transistor Clamped H-Bridge inverter (TCHB); Medium voltage application; Power quality problems.
A Novel Hybrid Discontinuous PWM Algorithm for 3L-NPC Inverter
by Li-ping ZHONG
Abstract: Wider linear modulation range, less switching loss and simplicity are the goals pursued by various modulation methods of multilevel inverters. This paper proposes a new hybrid discontinuous pulsewidth modulation (HDPWM) strategy for 3L-NPC inverter that can achieve the above goals to a certain extent. According to the position of the reference voltage vector and the actual situation of the neutral point voltage, different control modes and clamping types are selected. The neutral point voltage is controlled by DPWM strategy, which can not only greatly reduce the switch loss, but also maintain the balance of the neutral point voltage and expand the linear modulation range. The implementation of the algorithm combines the advantages of carrier-based PWM (CBPWM) and space vector PWM (SVPWM). There is no need to select the nearest three vectors (NTV) and calculate their dwell time. Only the reference voltage needs to be modified according to the control requirements, and then by comparing the modified reference voltage with the carrier, the driver pulse required by the switching devices can be generated. Compared with the existing PWM methods, it is more simple and easy to implement. Experimental results results verify the validity of the method.
Keywords: Hybrid discontinuous pulsewidth modulation; space vector pulsewidth modulation; clamping type; neutral point voltage balancing; output level sequency type.
Optimum Regulation of THD Profile in Multilevel Inverter Using Parameter-less AI Technique for Electrical Vehicle Application
by KAUSHAL BHATT, Sandeep Chakravorty
Abstract: This article proposes investigation on harmonic profile improvement using a novel fitness function in the multi phase multilevel inverter. For the proposed study in this paper, three-phase, seven-level cascaded H-bridge (CHB) multilevel inverter (MLI) is considered. Modulation of the stepped waveform output of the MLI is done using selective harmonic elimination (SHE) method. Many algorithms are proposed for solving the set of nonlinear transcendental trigonometric equations for SHE methods. Teaching learning based optimization (TLBO) algorithm is a parameter less optimization technique. Due to the lack of controlling parameters, the proposed algorithm is most robust among the family of artificial intelligence (AI) techniques. In this paper, an investigation is carried out on a novel fitness function proposed for controlling total harmonic distortion (THD) for the proposed inverter. It is observed that the proposed fitness function improves THD profile below IEEE standards. It is also observed that THD profile obtained through this method is far better than THD profile obtained through various proposed methods so far. The results of THD profile from the MATLAB Simulink simulations are verified experimentally using 7-level 3-phase hardware controlled by Arduino MEGA 2560 low cost controller.
Keywords: Multilevel inverter; artificial intelligent algorithm; teaching learning based optimization technique; selective harmonic elimination; total harmonic distortion.
BSA Based Analysis of Three-Phase Standalone Asynchronous Generator Using Two-Port Network
by Sambaran Ray, Himadri S. Chatterjee, Dipanjan Samajpati, Sankar N. Mahato, Nirmal K. Roy
Abstract: This paper presents the analysis of steady-state behavior of a three-phase standalone asynchronous generator (SAG) supplying three-phase load based on binary search algorithm (BSA). The concept of two-port network is used to model the generator system along with the load. Two model equations developed from the modeling of SAG are solved by BSA to get the frequency (a) and magnetizing reactance (Xm). The performance equations are formed with the help of frequency, magnetizing reactance and magnetizing characteristics of the machine to understand the steady-state behavior of SAG. The waveforms of generated voltages and currents in the generator are also investigated and their corresponding harmonic contents are recorded. The simulated results are verified through the experimentation and it shows that the experimental results closely agree with the simulated results. The BSA based analysis of three-phase SAG is easier, more efficient and accurate.
Keywords: Binary search algorithm; self-excited induction generator; standalone asynchronous generator; steady-state performance; two-port network; waveform.
Advanced Predictive Flux Control For B6 Inverter Fed Induction Motor Drives
by Wiem ZOUARI, Imen NOUIRA, Bassem EL BADSI
Abstract: Predictive torque control (PTC) strategy has already been introduced to cope with the problem of the torque and flux ripples of AC machines. However, the simultaneous control of the electromagnetic torque and the stator flux magnitude in conventional PTC scheme is not very trivial. Alternatively, the predictive flux control (PFC) strategy has been suggested based on removing the weighting factor from the implementation scheme. This paper proposes the development of two new phase-clamping (PC) PFC schemes, founded on the basis of modulating two legs of the two-level inverter fed induction motor (IM). Both PC-PFC strategies allow the clamping of one stator phase to the positive or negative terminals of the dc-bus voltage during each 60
Keywords: Predictive Flux Control; Induction Motor; Phase-Clamping; Duty-Cycle Optimization; Switching Frequency; Harmonic Distortion; flux and Torque ripple.
Design, Implementation and Performance Evaluation of Different Digital Control Techniques for Current Controlled DC-DC Buck Converter
by Dipen M. Vachhani, Rajesh Arya, Uma Rathore Bhatt
Abstract: The paper presents modelling, control architecture, analysis and design of digital compensators for single feedback-loop voltage mode control as well as two feedback-loop average current mode control and peak current mode control of current controlled DC-DC Buck converter operating in continuous conduction mode with output current as control variable. The compensators are derived using digital redesign approach, simulated on MATLAB, implemented as control algorithms on Texas Instruments 32-bit TMS320F28069M microcontroller platform, and experimentally validated by testing with a laboratory prototype of current controlled Buck converter. Simulation and experimental results are discussed, compared and evaluated for converter output current performance in tracking reference current signal as well as in regulation against input voltage and load disturbances. Salient features of each control technique are identified and described to determine its suitability in applications of DC-DC converters requiring controlled output current.
Keywords: Digital control techniques; digital voltage mode control; digital average current mode control; digital peak current mode control; current controlled DC-DC Buck converter; continuous conduction mode; digital redesign; digital compensators; type-2 compensator; 2p2z compensator.
Advanced sensorless nonlinear control strategy for grid-connected photovoltaic systems via the two-time scale singular perturbation technique
by Youssef MCHAOUAR, Abdelmajid ABOULOIFA, Aicha EL ALLALI, Ibtissam Lachkar, Josep M. Guerrero, Chaimaa Taghzaoui
Abstract: This paper presents a new control strategy for grid connected photovoltaic (PV) system. The system consists of a solar panel, a boost power converter, and a full-bridge inverter with filter inductor connected to the grid. The control objectives are threefold: i) tracking the maximum power point (MPPT) of the PV panel; ii) regulating the DC-link voltage to a given reference to ensure the power transferring from the PV panel to the grid; iii) ensuring a unity power factor in the grid such as the currents injected must be sinusoidal with the same frequency and the same phase as the grid voltage. To achieve these control objectives, a multi-loop controller is synthesised using a high-gain output feedback controller and the two-time- scales singular perturbation technique. The addressed control problem involves several difficulties including the nonlinear characteristic of the PV, the nonlinear dynamics of the converters, and the existence of a number of state variables that are inaccessible to measurement. To address this problem, two-time-scale sliding mode observers are added which allow estimating, simultaneously, the solar panel current and the grid voltage. To show that all control objectives are asymptotically accomplished, a formal analysis based on the singular perturbation method and the average theory is carried out. This theoretical result is confirmed by simulations under MATLAB Simulink illustrating the performances and the strong robustness with respect to climate changes.
Keywords: Photovoltaic system; singular perturbation technique; two-time scales sliding mode observer; nonlinear control; averaging theory.
Performance Investigation of Transformer-less DSTATCOM in Grid-connected Solar-PV Distributed Generation System with Insolation Variation
by Meenakshi Rastogi, Aijaz Ahmad, Abdul Hamid Bhat
Abstract: This paper addresses the application of DSTATCOM in a grid-connected solar PV distributed generation system when the insolation variation takes place. The solar-PV panel is connected to the grid at a point of common coupling to supply real power to the load and surplus real power to the grid at light loading conditions. When DSTATCOM is integrated with a grid-connected solar-PV system, it injects reactive power with real power simultaneously and contributes to the mitigation of power quality problems which is created by the solar-PV system or different loading conditions. DSTATCOM also results in power factor correction and zero voltage regulation of the distribution system. The solar-PV output power has fluctuations and its waveform carries harmonics with it. DSTATCOM also contributes to maintaining the power system stability, which may get deteriorated by the solar system as the solar-PV system is unstable. DSTATCOM maintains the DC-link voltage constant and helps the solar-PV system to work smoothly. In this paper, the simulation model of a 3-phase 3-wire Distributed Generation System based on Synchronous Reference Frame (SRF) control strategy has been designed to demonstrate the performance evaluation of DSTATCOM in a solar-PV distributed generation system with variation in solar insolation. The simulation model has been designed in MATLAB/Simulink and SimPowerSystems software. Various simulation results have been presented. The digital real-time simulator has also been used and the real-time experimental results have been presented to validate the correctness and effectiveness of the proposed system and its control.
Keywords: Digital Real-time simulation; Distribution Static Synchronous Compensator (DSTATCOM); Sinusoidal Pulse Width Modulation (SPWM); Synchronous Reference Frame (SRF) theory; Solar-PV panel; Distributed Generation System; Power Factor Correction (PFC); Zero voltage Regulation (ZVR); Solar Insolation.
Modulation Technique Based on Low Computational SVPWM for Reduced Switch Multilevel Inverter Hardware Implementation
by Jose Jacob, Sarin MV, Chitra A., RaziaSultana W
Abstract: This work envisages promoting an experimental analysis of a reduced switch asymmetrical multilevel topology when controlled with different modulation schemes. For Investigation, two modulation schemes are used, i.e (a) SPWM Sinusoidal Pulse Width Modulation and (b) SVPWM- Space Vector Pulse Width Modulation techniques. The algorithm proposed here is a general one, which can be applied to any N- level inverters without much complexity as compared with standard space vector techniques. The output of Multilevel Inverter (MLI) is evaluated by the presence of Total Harmonic Distortion (THD) for available modulation techniques. A seven-level output voltage has been generated by the proposed topology. Complete modeling by the numerical equation is done with MATLAB/Simulink tool. To give proof of the numerical results, an experimental setup has been implemented using dSPACE 1104. The effectiveness of the proposed space vector algorithm over SPWM technique is shown experimentally. The experimental verification reveals that the low computational SVPWM outperforms the conventional schemes.
Keywords: Power converters (DC-AC);PWM inverters;SVPWM;power MOSFET;inverters;.
A H?-based approach for sensorless control of BLDC motors fed with four-switch inverters
by Nouha Triki, Mohamed Abbes, Souad Chebbi
Abstract: BLDC motors are fast and robust synchronous machines and, therefore, they can be suitable for many high-end applications. This paper presents the design and the implementation of a cost-effective sensorless control strategy for brushless DC motors fed with a four-switch inverter. The proposed control technique simplifies the hardware implementation of such drive system since only two current sensors are used to achieve accurate estimation of the rotor position. It can be used whether the neutral point of the stator is accessible or not. In this method, a H?-controller was designed to control phase currents. A disturbance observer is used to estimate the back-EMFs of the rotor. These variables was used as the inputs of a phase locked loop to estimate the rotor position. The performances of this system were validated through simulation results. It was shown that the rotor speed remains close to the desired reference and the estimated angle is synchronized with the actual back-EMF. Compared with existing solutions, the proposed method allows the limitation of switching losses by the removal of the hysteresis controllers and the possibility to use standard driver circuits with internally set deadtime. Finally, an experimental prototype was built to verify the correctness of the presented control method.
Keywords: BLDC motor; four-Switch inverter; H? control; disturbance observer; Sensorless control.
Harmonic/Inter-harmonics Detection using Modified Exact Model Order based ESPRIT
by Ankit Srivastava, A.N. Tiwari, S.N. Singh, Praveen P. Singh
Abstract: Problems related to harmonics/interharmonics are growing in power system rapidly with the increasing use of power electronic devices. This paper focuses on estimating harmonics/interharmonics using MEMO-ESPRIT (Modified Exact Model Order Estimation of Signal Parameters via Rotational Invariance Technique). The modified EMO method is used to reduce the computational burden in detecting the harmonics/interharmonics components. The EMO estimation performs the calculation of the relative difference of every eigenvalue while modified-EMO utilizes the fact that two consecutive eigenvalues belong to the same frequency components and therefore, it removes those points and takes their average for RD calculation. Comparison has been made between EMO (Exact Model Order) and MEMO to demonstrate the effectiveness of MEMO. Moreover, various parameters values like noise, size of autocorrelation matrix, etc. are varied to see their effect on the computational burden and accuracy of the MEMO method. Performance of the MEMO-ESPRIT algorithm is analyzed with synthetic signals, single-phase PWM inverter and 250- kW grid-connected PV arrays using MATLAB/Simulink. The root-mean-square relative error has been obtained to validate the accuracy of the algorithm.
Keywords: Harmonics/interharmonics estimation; MEMO; FFT; ESPRIT.
Modelling, Analysis & Control of Bidirectional SEPIC Converter for Energy Storage Applications
by Arnab Ghosh, Jayadev Meher, Subrata Banerjee
Abstract: Energy storage system appears to be very promising field of research for rapidly increased requirements of applications renewable sources in daily life. The DC-DC bidirectional converters (BDCs) are globally known for its versatile applications in battery chargers, electric vehicles (EVs), solar PV modules with energy storage systems, smart/ microgrid, telecommunication systems etc. Such demanding applications are mostly essential for suitable bidirectional converters for delivering the energy both the directions. In this work, the closed-loop analysis, modelling and control of a DC-DC bidirectional SEPIC converter with classical controllers (like as proportional integral derivative (PID) controller, Type-II controller & Type-III controller) and advanced controller (such as Internal Model Controller (IMC)) are demonstrated. The bidirectional SEPIC converter has been modelled here by using state-space averaging (SSA) method. It is noticed that bidirectional converter with IMC shows better controlling action compared to other classical control algorithms for its better steady-state and transient responses. Finally, experimental verification of proposed closed-loop converter control is performed.
Keywords: Bidirectional SEPIC Converter; Small Signal Analysis; Classical Controllers; Advanced Controller; Energy Storage System;.
Single Phase Cross Connected Sources Asymmetric T-Type Multilevel Inverter with Fault Tolerant Capabilities
by Vinay Kumar, Sanjeev Singh, Shailendra Jain
Abstract: This work presents a cross connected sources asymmetric T-type multilevel inverter (CCSATT-MLI) for single phase operation with fault tolerant (FT) capabilities. The presented topology uses only one extra power semiconductor switch in the CCSATT thirteen-level (13L) inverter for fully FT operation. The paper uses two control schemes namely phase opposition disposition sinusoidal pulse width modulation (POD-SPWM) and nearest level control (NLC) for achievement of desired results under single switch open circuit (SSOC) fault. The obtained simulation results of proposed topology using MATLAB/Simulink are presented to show FT operation of the MLI under any SSOC fault. The simulation validation are validated under each switch fault using OpalRT hardware in loop (HIL) platform. The presented topology is also compared with recently reported MLI topologies for reduced number of count claim and effective FT operation in symmetric as well as asymmetric configurations.
Keywords: Asymmetric T-type; cross connected source; fault tolerant; multilevel inverter; Nearest level Control; Pulse width Modulation; Single switch open circuit; Total Harmonic Distortion.
Coordinated control of wind farm and supercapacitor energy storage system for dynamic performance reinforcement of multi-area power systems
by Asima Syed, Mairaj Ud-Din Mufti
Abstract: In this paper, a simple and effective control approach to exploit the primary frequency support competency of doubly fed induction generator (DFIG)-based wind turbines (WT) is presented. Furthermore, a small rating supercapacitor energy storage system (SCESS) is also integrated to reinforce the frequency regulation in the studied multi-area power system. A control-oriented strategy is employed to develop a discrete-time predictive control (DPC) for SCESS. The dynamic energy level thresholds are generated by representing the SCESS primary control by a first-order lag block for obtaining a discrete-time state-space model which yields the modified power constraints. Furthermore, the power thresholds of the power conditioning system (PCS) are chosen meticulously. The uprightness of the proposed scheme is manifested by the time-domain simulation results exhibiting considerable damping of the power system oscillations along with substantial curtailment in frequency nadir, with all the power and energy constraints of SCESS accounted for. The eigenvalue analysis is also carried out to validate the MATLAB/Simulink-based simulation results.
Keywords: doubly fed induction generator; frequency support; discrete-time predictive control; supercapacitor energy storage.
Performance evaluation of a standalone hybrid microgrid for a rural community using various dispatch strategies
by Vijay Garg, Sudhir Sharma
Abstract: Distributed energy sources prove to be a viable alternative for electricity in rural/remote areas. In this paper, the performance of a standalone hybrid microgrid comprising of solar photovoltaic (PV), diesel generator (DG), and battery energy storage system (BESS) has been evaluated for a small rural community. The overall aim is to propose sustainable, economical and reliable electricity supply in rural/remote areas. The optimum sizing of various units has been evaluated using hybrid optimisations multiple energy resources (HOMER) simulations with four dispatch strategies, i.e., load following, cycle charging, combine dispatch, and predictive dispatch. The outcomes show that the PV-DG-BESS system is an optimal solution based on net present cost (NPC) and cost of energy (COE) parameters under a predictive dispatch strategy. The sustainability of the optimum hybrid microgrid has been evaluated using sensitivity analysis using various input parameters.
Keywords: hybrid microgrid; solar photovoltaic; hybrid renewable energy sources; dispatch strategies; sensitivity analysis; cost of energy; COE; battery energy storage system; BESS.
PV Micro-inverter with Passive Equalizer for High Power Acquisition Ratio
by Dongchun Wu, Fei Zhu, Jiawei Tang, Jun Liu, Yunya Wu
Abstract: Micro-inverter is one of the important and efficient utilisation forms of photovoltaic power generation. Generally, there are 34 sub-modules in a PV module. When the light intensity is different among sub-modules, the output power of the PV module is dramatically decreased even if a micro-inverter is equipped. A passive equaliser integrated into full-bridge PV micro-inverter is proposed, which is composed of cascaded voltage-doubler rectifiers and a LC series resonant network. The proposed equaliser can be well operated without any additional control and it can supply the current/energy to the sub-module under part shadow. At last, all of the PV sub-modules can be operated near their maximum power point. The operational modes and the design principle of parameters are analysed. The simulation and experimental results verify the obvious advantage in increasing the power acquisition rate to PV panel.
Keywords: PV micro-inverter; voltage equaliser; differential power processing; DPP; LC resonance; power acquisition ratio.
Performance Investigation of Reweighted Zero Attracting -LMS based Dynamic Voltage Restorer for Alleviating Diverse Power Quality Problems
by Humeera Altaf, Abdul Hamid Bhat
Abstract: Dynamic voltage restorer (DVR) has proven to be the most coherent, effective and economic answer to voltage based power quality problems. This work details the design, investigation and experimental validation of reweighted zero-attracting least mean square (RZA-LMS) based DVR addressing the issues like voltage sag, voltage swell, voltage harmonics, voltage imbalance and combination of these. The RZA-LMS based control algorithm is proposed for producing reference voltage signals. The features of proposed algorithm include finite-time convergence, simplicity and improvement in the robustness of the system against varying parameters. The viability of DVR controller is assessed by employing MATLAB/Simulink and Simpowersystem software. The performance of proposed DVR is experimentally investigated using digital real-time simulator.
Keywords: power quality problems; dynamic voltage restorer; DVR; reweighted zero-attracting least mean square; RZA-LMS; compensation technique.
Power Quality Improvement of Microgrid Fed Electric Ship using Fuzzy Controlled Multi-Pulse/Multi-Level Converter Based VFD
by Ahmed Mansour, Ahmed Hossam-Eldin, Mohamed Elgamal, Karim Hassan
Abstract: This paper investigates a harmonic mitigation technique for modern Electrical Propulsion Ships (EPS) Microgrids (MG) using a fuzzy controlled Multi-Pulse Rectifier (MPR) and Multi-Level Inverter (MLI) based Variable Frequency Drive (VFD). In this paper, the proposed MPR-MLI-VFD system is studied using different-pulses rectifiers and different-levels inverters based VFD to achieve proper mitigation of the harmonics in the main generating power system of the ships within the marine classification societys limitations for harmonics. This is achieved using a proposed low harmonic multi-pulse rectifier based on zigzag transformers. Moreover, the voltage harmonic distortions at propulsion motor feeder buses are minimized using the proposed MLI. A simple fuzzy logic control system is proposed for the VFD speed control. The voltage balancing control system for the diode clamped multi-level inverters is implemented using a fuzzy control system. Matlab / Simulink is used for the simulation and validation process.
Keywords: Power quality; Harmonic mitigation; Electrical propulsion ship; Multi-level inverter; MLI voltage balancing; Multi-pulses rectifier; Fuzzy logic control; VFD.
Review of on-board conductive charger topologies for electric transportation
by N. Vijaya Anand, A.V. Jaya Sai Praneeth, Naveen Yalla, Vijay K. Sood
Abstract: This paper presents an overview of on-board conductive charger topologies for electric vehicles (EVs). Battery packs in electric and plug-in hybrid electric vehicles (EVs/PHEVs) need frequent energy refills to fulfil their duty cycles and overcome the range anxiety of vehicle owners. Due to the limited availability of fast charging infrastructures, all automotive manufacturers prefer an on-board battery charger in their vehicles. However, there are power level limitations for these chargers because of the weight, space and cost constraints. On-board charging systems can be either conductive or inductive. This paper reviews the topologies that are involved in conductive charging only. Globally, all automotive companies provide levels 1 and 2 for residential charging of vehicles. Single- and two-stage power converter topologies are summarised with their limitations. Furthermore, the current trends in the DC-DC converters for the two-stage conversion battery charger topologies are also outlined. This paper provides an overview of various topologies and configurations involved in EV charging with their limitations.
Keywords: AC-DC converters; DC-DC converters; electric vehicles; EVs; level 1 charger; level 2 charger; level 3 charger; on-board chargers; power factor correction; PFC.
Common Mode Voltage Analysis and Reduction Technique for Nine Switch Inverter Fed Dual Load System
by Ashish Dongre, Jyoti Prakash Mishra, Ravi Kumar Majji
Abstract: Nine switch inverter (NSI) is a dual output topology that suffers from the common mode voltage (CMV) issues similar to conventional single output drive systems. A significant amount of literature is available to solve CMV in the traditional drive system, but there is a lack of literature on NSI CMV issues. The work presented in this paper serves to unify the understanding of different pulse width modulation (PWM) techniques applied to NSI and their effects on CMV. PWM techniques used in this study include sinusoidal, modified sinusoidal, discontinuous, and space vector PWM. This paper also investigates the possibility of reducing the CMV peak during zero vector states using two more switches in NSI without affecting the output voltage. To validate the proposed concept, an NSI fed dual load system is developed using MATLAB Simulink, and a real-time simulator OPALRT-OP4510 is used to support the findings.
Keywords: common mode voltage; CMV; sinusoidal pulse width modulation; SPWM; discontinuous pulse width modulation; DPWM; SVPWM; nine switch inverter; NSI.
A Single-Phase Level-Shifted Duty Controlled Multilevel Rectifier Based EV Charger for Wide Output Voltage Range
by Rheesabh Dwivedi, Sanjeev Singh, Bhim Singh
Abstract: Nowadays, electric vehicles (EVs) are gaining popularity as customers and environment-friendly option owing to the rise in petroleum prices and pollution, respectively. The battery is the prime source of power for EVs. This paper presents, a level-shifted duty controlled multilevel power factor correction (PFC) AC-DC converter, followed by a phase-shifted full-bridge converter (PSFBC) as an efficient charging solution for EVs. The adopted topology uses lesser semiconductor switching devices than traditional multilevel converters, which minimises switching losses, making it a good choice for compact EV charger. Complete system design is carried out for a single-phase, 3.3 kW, EV charger, with 220 vrms AC input and 4872 V DC output voltage for batteries. This EV charger has improved the system reliability and efficiency, along with the near-unity power factor (UPF) in compliance with the international IEC-61000-3-2 PQ standard. MATLAB/Simulink and experimental results are presented to validate the aforementioned functionalities of this EV charger.
Keywords: five-level converter; level-shifted PWM; electric vehicles; battery charging; power quality.
Power quality improvement of the grid-tied hybrid AC-DC microgrids by adding the bi-directional series converter
by Mohsen Rezaie Estabragh, Ali Dastfan, Morteza Rahimiyan
Abstract: The power quality problems of the utility voltage are transferred to the grid-tied microgrid. With the conventional organisation of a hybrid AC-DC microgrid, the controller cannot compensate the voltage of the AC bus. The paper offers the bi-directional series converter between the common DC bus and the utility to compensate the sag/swell/harmonics of the utility voltage. The controllers are designed based on the instantaneous reactive power theory and predictive control. The interfacing converter compensates the reactive power and harmonics components of the nonlinear AC load and the voltage of the DC bus along with bi-directional transmission power. The performance verification is done by simulating the typical microgrid in MATLAB/Simulink. The AC bus voltage and utility current become pure sinusoid. The results show improvement in the THD of source current and load voltage while the voltage of the DC bus is controlled at the reference voltage.
Keywords: suggested organisation of hybrid AC-DC microgrid; bi-directional AC-DC series converter; power quality improvement; instantaneous reactive power theory; predictive control.
Design of a Novel Double Closed Loop System of the Vienna Rectifier in the Pre-stage of UPS
by Ningzhi Jin, Long Zhang, Hongchao Chen, Kai Zhou, Xiaogang Wu
Abstract: Aiming at the problems of complex parameter design and slow system dynamic response in the traditional double closed-loop PI control system of the Vienna rectifier, this paper proposes a novel double closed-loop control strategy of variable exponential approach law sliding mode control (SMC) and finite control set model predictive control (MPC). To begin with, a mathematical model of Vienna rectifier circuit is established. Then, the control algorithms of SMC voltage loop and MPC current loop are derived and designed. Finally, the applied control method is verified with simulation in MATLAB. The results show that the proposed system can improve the input current quality, and leads to a better steady-state response and dynamic performance of the DC output voltage, current and neutral point potential.
Keywords: Vienna rectifier; double closed-loop control; sliding mode control; model predictive control.
Comprehensive Analysis of BLDC Motor Faults in Electric Vehicle Transportation
by Adil Usman, Bharat Singh Rajpurohit
Abstract: The faults prospective are higher for any BLDC motor, driven under a constant and continuous operating period. The possibility of getting susceptible to winding short-circuit faults and rotor demagnetisation effects, is more frequently discerned. The winding insulation breakdown introduces stator inter-turn fault (SITF) conditions in the machine which has consequent detrimental impact on the rotor permanent magnets (PMs). The cumulative effect of fault stimulates rotor demagnetisation, intensifying the effect of faults. This paper aims in classifying the motor faults employed in electric vehicle (EV) transportation. Depending upon the machines characteristic performance in terms of electrical signatures like, motor current signature (MCS) and back-EMF (BEMF), and mechanical signatures like frequency and vibration spectrum; a unique classification to fault is provided. The proposed research models investigate the performance of a machine drive under both individual and combined fault conditions, to give a significant outcome to the research findings. The closed loop motor drive operation is performed using an advanced field remodelling (AFR)-based technique which employs fuzzy logic controller (FLC). The developed drive-controller-system minimises the steady state error under motor operating conditions and has a clear discrepancy in terms of machine quantities during faults.
Keywords: advanced field remodelling method; AFR method; brushless DC motors; BLDC motors; demagnetisation; finite element method magnetics; FEMM; numerical methods; NMs.
Research on Bidirectional Isolated On-board Charger Based on CLLC Resonant Converter
by Kai Zhou, Zan Liu, Dongyang Sun, Ningzhi Jin
Abstract: This paper presents a bidirectional isolated on-board charging system for electric vehicles. The charging system is composed of a front-end circuit and a back-end circuit. The front-end circuit is a bidirectional totem-pole power factor correction converter, and the back-end circuit is a bidirectional CLLC resonant converter. According to the design requirements of the charging power supply system, the key parameters of the CLLC resonant converter are selected and calculated. Through sampling, the output voltage and input current of the front-end circuit are obtained, and compared with the reference value and compensated, and the on-off time of the switch in the front-end circuit is finally controlled. The latter circuit uses the loop control mode to control the switch frequency of the switch to achieve constant voltage and current charging. A 3.3-kW vehicle charging system prototype was constructed. The simulation and experimental results verify the correctness of and design.
Keywords: vehicle charging system; bidirectional totem-pole converter; CLLC resonant converter; zero-voltage switching.
DCPWM based conducted EMI noise mitigation in ULL converter for EV applications
by Srinivasan Kalaiarasu, Sudhakar Natarajan
Abstract: Conducted electromagnetic interference (EMI) noises are produced due to the fast-switching process in power converters and result in the degradation of power electronic components in electric vehicles (EVs). In this work, a DCPWM technique-based EMI mitigation process has been proposed for a high gain ultra-lift Luo-converter. Due to the high switching frequency of 200 kHz, EMI noise has been generated. By implementing the DCPWM technique, the above-mentioned issues are nullified. The conducted EMI mitigation level is analysed through common-mode noise, differential-mode noise, and power spectrum density. In this proposed method, a field-programmable gate array has been used to generate digital chaotic pulses by applying an RCFMFD approach. From the observation, 16 dBV, which is equal to 6 V of conducted EMI noise, has been reduced as per EMC-CISPR 11 standard limit by executing the proposed DCPWM technique compared with the periodic PWM technique in the ultra-lift Luo-converter for EV applications.
Keywords: conducted EMI; power spectrum density; PSD; digital chaotic pulse width modulation; DCPWM; field-programmable gate array; FPGA; randomised carrier frequency modulation with a fixed duty cycle; RCFMFD.
DESIGN AND IMPLEMENTATION OF STATIC BATTERY CHARGING STATION FOR ELECTRIC VEHICLE
by MANISH KUMAR DWIVEDI, JAYAPRAGASH R, Senthil Kumar.N.
Abstract: This paper presents an efficient hybrid battery charger (HBC) for an electric vehicle (EV). The HBC incorporated with maximum power point tracking (MPPT) algorithm receives input from the PV panels to charge the batteries when the solar insolation levels are high and is shifted to the grid at times of reduced insolation level. The HBC is implemented using two topologies. A multi-stage charger (MSC) consisting of a boost and buck converter integrated together and a single-stage charger (SSC) consisting of single-ended primary-inductor converter (SEPIC). Both the topologies are simulated in MATLAB/Simulink environment and compared. The MPPT algorithm is applied and the charge control algorithm is devised and applied for HBC. Finally, a scaled down 250W SSC is implemented in a hardware model. A modified perturb and observe (MP&O) MPPT is applied that would reduce the time complexity of the algorithm and would be more efficient.
Keywords: hybrid battery charger; HBC; maximum power point tracking; MPPT; MP&O; multi-stage charger; MSC; single-stage charger; SSC; SEPIC.
A Novel Concept of Extreme Fine Tuning in Harmonic Profile Improvement in Multilevel Inverter for Electrical Drives
by KAUSHAL BHATT, SANDEEP CHAKRAVORTY
Abstract: This article proposes a novel concept of improving harmonic profile in multilevel inverter (MLI) using ratio rule method. THD minimisation in MLI using selective harmonic elimination (SHE) approach using various optimisation techniques is covered in several literatures followed by further THD reduction using alterable DC sources. These methods discussed in various literatures uses rigorous derivations of constants that are used for further reduction of THD profile. This article introduces ratio rule method for further reduction of the THD in multilevel inverter, after optimisation process using various algorithms. The proposed study is conducted using the SHE approach for THD reduction using genetic algorithm followed by further THD reduction using ratio rule. A three-phase seven-level cascaded H-bridge inverter is simulated in MATLAB as well as its hardware is implemented for deriving the proof of proposed concept. It is found that the proposed method is faster, easier and produces a maximum of 12.60% reduction in THD profile.
Keywords: cascaded H-bridge inverter; multilevel inverter; genetic algorithm; total harmonic distortion; THD; electrical drives; ratio rule method.