International Journal of Powertrains (14 papers in press)
Realizing ZVS and ZCS in a Continuous Conduction Boost Converter with Boundary Mode Control
by Nagesh Vangala, Srinivasa Rao Gorantla, Rayudu Mannam
Abstract: Boost regulators working in the continuous conduction mode (CCM) are very popular in switch-mode power conversion. This configuration is widely adapted for Power Factor Correction (PFC) in Switch mode AC to DC converters. For lower power levels of up to 200 watts, boundary conduction mode (BCM) PFC is adapted, and for power requirements beyond about 200W, CCM boost with average current control scheme is favored.
A novel technique is proposed in this paper to achieve complete soft-switching viz. Zero Voltage Switching and Zero Current Switching for the main boost switch in CCM mode. The uniqueness of the scheme lies in not adding any auxiliary MOSFET switch and /or control algorithm. All the switching elements exhibit soft-switching, thus improving efficiency and reducing the EMI considerably. Most of the reported techniques for soft switching in CCM boost utilize additional active switches.
A working model is fabricated to demonstrate and validate the scheme. The test results and the waveforms are presented and analyzed. An 800 watts PFC converter exhibiting complete soft switching is built using the proposed technique and is evaluated for its performance.
Keywords: Boost Converter; Continuous Conduction mode; ZVS; ZCS; Soft Switching; PFC pre-regulator; Variable Frequency; Resonant Converter.CCM; BCM Control.
Design of a test rig in support of E-clutch dynamics characterization, modelling, and control
by Matija Hoić, Mario Hrgetić, Joško Deur, Andreas Tissot
Abstract: E-clutch systems have emerged recently as solutions that allow the powertrain control system to operate the clutch, while the driving procedures remain the same as with the regular manual transmissions (MT). These systems offer possibilities of improved fuel economy and driving comfort over MT systems, while the driver maintains the existing driving habits. This paper presents design of a test rig developed for a dry E-clutch equipped with a hydrostatic actuator mechanism driven by a spindle-based electric servomotor. The main purpose of the test rig is to provide a basis for experimental characterization of both static and dynamic behaviours of the E-clutch, as well as to facilitate E-clutch model validation and control strategy verification. The use of the test rig is illustrated through presenting recordings of basic E-clutch static curves and time responses. These recordings are employed to validate axial dynamics and thermal dynamics models of an E-clutch, which are presented in the paper, as well.
Keywords: control; design; E-clutch; modelling; test rig.
IMPROVED EM ALGORITHM IN SOFTWARE RELIABILITY GROWTH MODELS
by Sudharson D., Prabha D
Abstract: In recent era many reliability models such as Littlewood-Verrall Model, Jelinski-Moranda model, Goel and Okumoto model, etc., are available in testing a software so that efficient application could be developed. The important issue in software reliability management includes evaluation, measurement and prediction about errors in the model. It is essential in software testing process to measure its reliability and researchers turned on many models to ensure better reliability to achieve high safety systems. In critical applications the requirement of software reliability is considered as important issues as the low reliability decreases the application performance. Fault identification related to reliability of the model as the faults reduces the reliability of the application and it brings the operation of user. Several factors that affects the reliability such as consistency, test coverage, complexity, operational realism, etc., In this complexity leads to faults in the model as it is also related to reliability so that once we start to develop and design the application complexity must take into an account. In delivering some high reliability software products these above factors must be included so that the expectation about product to the user community increases. This research workdescribes about an efficient model for identifying the faults in the software products using improved EM algorithm using gaussian function. The improved EM function includes k means algorithm together to perform the task.
Keywords: Fault identification; EM algorithm; k means algorithm; gaussian function.
How Suitable is Lithium-Sulfur Battery for Electric City Bus Application?
by Victor Calvo Serra, Abbas Fotouhi, Mehdi Soleymani, Daniel J. Auger
Abstract: Lithium-sulfur (Li-S) battery is a promising technology that can be considered as an alternative energy storage system in automotive and aerospace applications due to its higher energy density, safety and potential lower price in mass production compared to the existing battery technologies in the market. This paper investigates application of a new prototype Li-S cell in an electric city bus using computer simulations. For this purpose, MATLAB/Simulink software has been employed and a vehicle model is built and simulated according to the specifications of available electric buses in London city. An equivalent circuit model is parameterized for the new Li-S cell based on experimental data. Battery pack sizing is then performed by considering the maximum required power and also the desirable energy stored in the pack based on the Millbrook London Transport Bus (MLTB) driving cycle. Furthermore, impact of the battery packs mass on the vehicles range is studied and Li-S technology is compared with two commercial Li-ion batteries used in existing electric buses in London city. The results demonstrate that the proposed Li-S battery pack can fulfil the requirements of an electric city bus in terms of power while achieving a considerable increase in vehicles range with same weight of battery pack. However, Li-S cell prototypes still suffer from limited cycling life that prevents this technology to be commercialized for such an application at the time being.
Keywords: lithium-sulfur cell; modelling; battery pack sizing; simulation; electric bus.
Optimal Energy Management and Shift Scheduling Control of a Parallel Plug-in Hybrid Electric Vehicle
by Jure Soldo, Branimir Škugor, Joško Deur
Abstract: This paper deals with design of a control strategy for a parallel powertrain configuration of a plug-in hybrid electric vehicle (PHEV). The control strategy is aimed at minimising fuel consumption and number of gear shift events for a wide range of driving cycles, while keeping the battery state-of-charge within allowable range. A control-oriented backward-looking model of PHEV powertrain is used as a design basis. The control strategy combines a rule-based controller with an equivalent consumption minimisation strategy (ECMS). The ECMS uses both transmission gear ratio and engine torque as control variables, thus eliminating a need for designing a separate gear shift scheduling strategy and exploiting a full potential of powertrain efficiency improvement. The overall control strategy is designed for different characteristic operating regimes including charge depleting, charge sustaining, and blended regimes. The strategy is verified by computer simulation against globally optimal benchmark obtained by using the dynamic programming-based optimisation, whose results are also used for fine tuning of controller parameters.
Keywords: Energy management; ECMS; shift scheduling; control; plug-in hybrid electric vehicle.
A Novel Hybrid Space Vector Based Modulation Technique for Power Quality Improvement in a Wind Energy Conversion System
by Boopathi R., Jayanthi R, Mohamed Thameem Ansari M
Abstract: The paper develops a novel hybrid space vector pulse width modulation (HSVPWM) for improving the quality of power transfer from a permanent magnet synchronous generator (PMSG) based wind energy conversion system (WECS) to a three phase induction motor load. It includes a vienna rectifier (VR) based ac-dc converter in the front end and a voltage source inverter (VSI) for providing the variable frequency, variable voltage requirements of the induction motor load. The vienna rectifier attempts to offer almost a unity power factor and early sinusoidal input as the input to the VSI as part of resurrecting the shape of the supply side waveform to the motor. The formulation involves a three-phase three-level HSVPWM along with a novel hysteresis current control technique for generating the firing pulses to the power switches in the VSI. The simulation results reveal a higher fundamental component a lower total harmonic distortion (THD) and harmonic spread factor (HSF) for the inverter output voltage over the similar other pulse width modulation (PWM) schemes and allow it claim a space for its use in real world utilities.
Keywords: PMSG; Harmonics Elimination; Power Spectral Density; Vienna Rectifiers; Harmonic Spread Factor.
Marine Powertrain Simulation for Design and Operational Performance Evaluation
by Aboozar Gholami, Ali Jazayeri, Qadir Esmaili
Abstract: This research investigates the performance of a propulsion system and the emissions parameters of a merchant ship by using the consequences derived via a modular ship simulation model that is executed in Matlab/Simulink. In the model, numerous components of the drive system such as engine, shafting framework, propeller, and vessel are shown by separated blocks whereas proper interfaces and connections are utilized to swap the desired factors between the blocks. Therefore, the created model can be used to explore the steady state and transient behavior of the ship propulsion system and investigate the engine/propeller/shafting framework and vessel connections. Using this model the performance parameters of a ship in normal speed and slow steaming were calculated and investigated. In addition, the ships powertrain system was investigated using distributed-lumped parameter model. The shear stress analysis of the propeller shaft was performed using a distributed-lumped model and compared in two normal speed and slow steaming modes. Due to the models modular structure, its components can be modified and extended to be used in future new technologies and fuel evaluation as a part of the ship designing process.
Keywords: ship propulsion system; performance and emissions; Distributed-Lumped parameter model; Shear stress; Simulink; simulation.
Special Issue on: ISAECT 2018 Advanced Research on Powertrains
ANFIS-based hysteresis comparators with intelligent dual observer and speed controller of a direct torque control
by Chaymae Fahassa, Mohamed AKHERRAZ, Yassine ZAHRAOUI
Abstract: This article presents the adaptive-network-based fuzzy inference system (ANFIS) based direct torque control (DTC) for induction motor (IM). Direct torque control is distinguished by merging a simple structure with a good dynamic behavior, when compared with the other vector control techniques. Despite the cited advantages the DTC offers, some disadvantages are also present. For this aim, which consists of reducing the ripples in electromagnetic torque, flux and current; and to improve the IM response characteristics, the conventional hysteresis comparators of the torque, flux and the PI speed controller are replaced by others based on ANFIS technique. Furthermore, an intelligent dual observer is implemented to achieve sensorless control; merging a Luenberger observer (LO) based on ANFIS to insure the adaptation mechanism in order to estimate the rotor speed, and a Kalman filter (KF) to insure the flux components estimation. The proposed sensorless ANFIS-DTC shows a robust performance which is presented in reduced ripples, decreased overshoots, short time of rising and settling, in addition to high resistance to perturbations. The simulation results are validated using Matlab/Simulink.
Keywords: anfis; hysteresis comparators; dual observer; Luenberger observer; Kalman filter; sensorless DTC; induction motor.
Special Issue on: Advanced Powertrain Technologies for New Energy Vehicles Modelling, Control and Optimisation
Modeling and Estimation of Combustion Variability for Fast Light-off of Diesel Aftertreatment
by Bryan Maldonado, Mitchell Bieniek, John Hoard, Anna Stefanopoulou, Brien Fulton, Michiel Van Nieuwstadt
Abstract: Combustion phasing retard is commonly used on diesel engines to achieve faster aftertreatment light-off and lower tailpipe cycle emissions by increasing the enthalpy of the exhaust gas. More aggressive combustion phasing retard can achieve higher exhaust gas enthalpy at the cost of increased combustion variability, which can create vehicle noise, vibration, and harshness (NVH) issues. To avoid NVH while maximizing exhaust heating, it has been proposed that feedback from cylinder pressure sensors be used to control the coefficient of variation of the indicated mean effective pressure (CoV_IMEP) to a maximum allowable value by retarding combustion phasing. Therefore, a control-oriented combustion model that captures the stochastic properties of the cycle-to-cycle variability for IMEP has been developed for control design. Initial explorations have focused on using finite impulse response (FIR) filters to estimate CoV_IMEP and generate the feedback signal, which requires constant repopulation of a vector for filter states and recalculation of the windowed statistics. An infinite impulse response (IIR) filtering strategy using exponentially weighted moving averages is presented which reduces the computational and storage burden of generating online statistics. Note, however, that the methods for fast aftertreatment light-off are transient in nature due to the increase in engine coolant temperature, while the CoV_IMEP is a characteristic of a stationary stochastic signal. Therefore, this paper presents, in addition to the control-oriented combustion modeling, an unbiased estimation method for CoV_IMEP that accounts for engine transient conditions. Finally, the performance of the proposed IIR strategy is tested during an engine warmup phase to show that it is a suitable alternative for generating a feedback signal for control.
Keywords: estimation; filtering; stochastic systems; cycle-to-cycle combustion variability model; aftertreatment light-off; coefficient of variation.
Flash Boiling Hollow Cone Fuel Spray from a Piezoelectric Fuel Injector under Low Ambient Pressure
by Zengyang Wu, Libing Wang, Tiegang Fang
Abstract: In this study, an experimental study of the spray characteristics under flash boiling conditions from an outwardly opening piezoelectric gasoline direct injection fuel injector was conducted in an optically accessible constant volume chamber (CVC). Distinct spray structure is noticed when the ambient pressure is extended to a lower range (0.01 bar to 0.1 bar) under flash boiling spray regime. While the original hollow-cone structure is still observable, spray deforms from a hollow-cone structure to a diamond-like shape with a long central plume at the downstream of the spray. Liquid signals at the plume region are much weaker than the original hollow-cone shape region. Within this pressure range, a higher ambient pressure leads to a shorter central plume. Spray penetration length is greatly enlarged due to the change in spray structure. Spray under a lower ambient pressure penetrates much longer at the same time step. Fuel injection pressure and fuel injection duration has little effect on spray front penetration length development. Specially, the highest spray front penetration velocity observed at 0.01 bar is expected to approach to the local sound speed. Spray structure, spray penetration length and spray penetration velocity are mainly dominated by ambient pressure conditions in this study. Compared to isooctane fuel, commercial gasoline generates stronger flash boiling due to the wide boiling range, but the spray structures are quite similar.
Keywords: Flash boiling; Hollow cone spray; Low ambient pressure; Gasoline direct injection; Isooctane.
A comparative study of integral order and fractional order models for estimating state-of-charge of lithium-ion battery
by Yifan Zhang, Tao Sun, Yuejiu Zheng, Xin Lai
Abstract: Battery state estimation is a key technology for battery management systems for electric vehicles, and state-of-charge(SOC) estimation of battery is the basis for numerous state estimations. In this paper, five fractional order equivalent circuit models are compared and evaluated based on a LiNMC cell. First of all, the particle swarm optimization(PSO) is used to identify the parameters of the fractional order models, and the fractional Kalman filter algorithm is further adopted to estimate the SOC and compared with the SOC estimation obtained by the integral order models. The results indicate that the fractional battery model has higher accuracy, especially in the low SOC interval. Through comparative analysis of several fractional order models, it is found that the fractional order model with the Wurburg component can be better describe the battery characteristics in the low SOC interval. From the perspective of model accuracy and computational cost, the addition of the Wurburg element to the fractional second-order RC model is the best choice.
Keywords: lithium-ion battery; fractional order model; Kalman filter algorithm; state of charge.
Model-Based Electric Traction Drive Resolver Fault Diagnosis for Electrified Vehicles
by Tianpei Li, Giorgio Rizzoni, Qadeer Ahmed, Jason Meyer, Mathew Boesch, Bader Badreddine
Abstract: In electric and hybrid electric vehicles (EVs/HEVs) the electric traction drive plays an important role in producing driving torque. The motor torque request is calculated based on pedal positions from the driver and motor speed measurement from the position and speed sensor, typically the resolver. When there is a fault in the resolver that leads to inaccurate motor speed measurement, the vehicle supervisory controller may request undesired motor torque, which may lead to motor torque oscillations that could result in safety or degradation problems. This paper presents a model-based approach for diagnosing the resolver fault in the electrified vehicles, with focus on two typical types of faults, amplitude imbalance and quadrature imperfection. Before the diagnostic strategy is designed, resolver failure modes and fault propagation are analyzed using a high-fidelity hybrid electric vehicle powertrain simulator. The proposed diagnostic strategy is implemented and validated through model-in-the-loop simulation, augmented by experimental data.
Keywords: fault diagnosis; hybrid electric vehicle; electric traction drive; permanent magnet synchronous machine (PMSM); structural analysis.
Optimal Design of Discrete-Time Fractional-Order PID Controller for Idle Speed Control of an IC Engine
by Yi Yang, Haiyan H. Zhang, Wangling Yu, Li-Zhe Tan
Abstract: Fractional-Order PID (FOPID) controller, as a nonlocal generalization of the conventional PID controller, exhibits a better control performance for the complex system dynamics. This paper aims at proposing a discrete-time FOPID controller, which can be implemented in the digital computer to stabilize the variation of the idle speed of an internal combustion engine due to the occurrence of the external load disturbance. The idle speed of an internal combustion engine is the revolution speed of the crankshaft when the drivetrain is uncoupled to the engine and the throttle is completely closed. The nonlinear idle speed dynamics is linearized, and the linearized idle speed dynamics is approximated by a first order plus dead time (FOPDT) model so that a Ziegler-Nichols type tuning rule can be applied to the FOPDT plant to initialize the five parameters (K_p,K_i,K_d,?,?) of the FOPID controller. The parameters-initialized FOPID controller can stabilize the idle speed of the linearized model, but it may lose its control capability when it is applied to the nonlinear idle speed dynamics. Therefore, an optimization problem is constructed to minimize an integral squared error function within a small region around the initial value of the FOPID parameters. The problem is solved through genetic algorithm (GA). The optimal FOPID is discretized and applied to the nonlinear idle speed plant. The simulation results of the optimal discrete-time FOPID controller are compared to those obtained from a conventional discrete-time PID controller. The comparison study reveals that the optimal discrete-time FOPID controller secures an excellent control performance to the nonlinear idle speed model. This controller design methodology can be transformed and applied in other complicated systems.
Keywords: Fractional-Order PID; discrete-time FOPID; idle speed control; Internal combustion engine; FOPDT; Ziegler-Nichols type tuning rule; genetic algorithm.
Life Cycle Assessment (LCA) study for different options of sustainable mobility, including vehicle conversion
by Gianfranco Rizzo, Francesco Antonio Tiano
Abstract: The diffusion of electric and hybrid electric vehicles is accounted to be the most feasible solution for the mitigation of world energy consumption and environmental protection. However, massive electrification is not behind the corner due to the need of charging infrastructure, the increase of renewable energy production and the scrapping of the circulating fleets.rnrnIn this study a life-cycle assessment approach to address the issue of sustainable mobility. By using the GREET model software, the analysis shows that a sustainable option for reducing total energy consumption, greenhouse gases and pollutant emissions is the conversion of existing vehicles into electric car or into hybrid solar vehicle, as in the system developed at the University of Salerno. Conversion of vehicles should be addressed by institutions in order to enact rules and directives for a more conscious choice in terms of sustainable mobility.
Keywords: Hybrid Electric Vehicles; Electric Vehicles; Life-Cycle Assessment; Automotive; Greenhouse Gases; Energy Consumption; Solar Vehicles.