Electric Vehicle Traction System Research Articles

Backup Pattern for traction system of FWIA electric vehicle to guarantee maneuverability and stability in presence of motor faults and failures

Faults and failures in driving motors of four-wheel-independently-actuated (FWIA) electric vehicles can lead to hazardous accidents. To address this challenge, this paper introduces a novel “Backup Pattern” by grouping the driving motors into front and rear traction subsystems. This “Backup Pattern” ensures the optimal allocation of driving torque between functional motors, providing a reliable and effective mechanism to mitigate the impact of faulty motors on the vehicle’s overall performance. Based on the torque distribution strategy, a composite controller structure is presented, utilizing the second-order sliding mode algorithm to design both the traction controllers for longitudinal and differential torques and an active-front-steering (AFS) controller for additional steering angle. The composite controller not only enhances the vehicle’s maneuverability and stability but also copes with uncertainties and disturbances in the vehicle system. Hardware-in-loop (HiL) tests validate the superior effectiveness and robustness of the designed controller, showcasing its ability to enhance FWIA electric vehicle performance compared to the conventional first-order sliding mode control-based method.

DC/DC converter in the electric vehicle traction system

DC-DC converters are used in various electrical devices including the traction system of electric vehicles. Electric vehicles use synchronous motors with permanent magnets as drives. Their distinctive feature is the nonlinear dependence of the electromagnetic torque of the motor on its input voltage. One of the ways to improve the energy characteristics of an electric vehicle is to include a DC-DC converter in the engine power supply circuit. The study has examined the main types of DC-DC converters, studied their advantages and disadvantages; a method has been determined to increase the energy efficiency of an electric vehicle by using a multi-channel DC-DC converter as part of its power circuit. This structure makes it possible to reduce the requirements for individual power switches and converter elements, and is also optimal from the point of view of weight and size indicators, since converters of this type do not have a transformer. Based on the review, a multichannel DC-DC converter circuit has been selected for integration into the traction electric drive system. The Tesla Model S has been chosen as the base vehicle. Based on the calculated dynamic characteristics of the electric vehicle, main parameters of the DC-DC converter have been determined, computer simulation of the power plant of an electric vehicle with a DC-DC converter has been carried out in the Matlab Simulink software environment. The use of the converter improves the energy efficiency of vehicles, and is also a better solution compared to installing a battery with a higher voltage.

Energy Management and Control in Multiple Storage Energy Units (Battery-Supercapacitor) of Fuel Cell Electric Vehicles.

This paper presents a new approach of energy management for a fuel cell electric vehicle traction system. This system includes a supercapacitor, a traction battery of valve-regulated sealed lead-acid type, a high-performance permanent magnet traction system, and a power electronics converter. Special attention was placed on the coordination for managing the flow of energy from several sources to treat the concerns of prolonged electric vehicle mileage and battery lifetime for drivetrains of electric vehicles. Connection to a supercapacitor in parallel with the electric vehicle's battery affects electric vehicle battery lifetime and its range. The paper used a study case of an all-electric train, but the used methods can be applied on hybrid or electric train cases. Fuzzy logic control and proportional integral control methods were used to control the electric vehicle system. The results of these two control methods were examined and compared. The simulation results were compared between the proposed electric vehicle system and the traditional system to show the effectiveness of the proposed method. Comparison of waveforms was made with and without the supercapacitor. The proposed optimized energy management strategy could improve the overall performance of the hybrid system and reduce the power consumption.

Comprehensive Design and Study on Cogging Torque Reduction in Permanent Magnet Synchronous Motors for Electric Vehicle Technology

Owing to high efficiency, high power density, high torque to current ratio and high power to weight ratio, application of Permanent Magnet Synchronous drives has been escalating in electric vehicle traction systems. The major concern arises due to increase in cogging torque ripples. The presence of internal harmonic content leading to noise and vibrational disturbances, greatly sways the smooth operation of the motor. To address this challenge is the key to design of Permanent magnet Synchronous motor. Numerous techniques have been enacted upon for truncating the cogging torque thereby increasing the efficiency for electric vehicle application. This paper presents an exhaustive study on the methods adopted and proposes an optimised model for analysing the effect of skewing in Interior Permanent Magnet Synchronous Motor. Furthermore, the optimal design conclusions based on the proposed shape optimization were confirmed by finite element analysis (FEA) method carried out on RMxprt tool of ANSYS software.

Comparative analysis of different FOPI approximations and number of terms used on simulations of a battery-powered, field-oriented induction motor based electric vehicle traction system

Because of their enhanced performance, the fractional order proportional-integral (FOPI) controllers are becoming an appealing choice for controlling induction motor speed. To implement FOPI controllers, several fractional order integral approximations are available in the literature. The approximation used, and the order of approximation affects the speed tracking, transient response, and induction motor power consumption. This further affects the energy consumption analysis if simulations are conducted based on such approximations. In this paper an electric vehicle (EV) traction system is simulated to investigate the effect of such approximations on the simulations of a battery powered, induction motor driven EV system. The system consists of an indirect field-oriented induction motor, a lithium-ion battery bank, and a three-phase inverter. This work presents a quantitative analysis of the performance of FOPI controllers using different approximations, and order of approximations is presented. The controllers are evaluated based on speed tracking, transient response, computational time, and power consumption. Both step functions and standard drive cycles are used as the speed reference signal to evaluate the effects of using different approximations and different orders of approximation, when different references are used. This work establishes a reference set of simulations that can be used to infer the amount of error in battery state of charge, and state of health analysis conducted on such an EV system, when dealing with FOPI controllers under different approximations and related settings.

Battery Energy Management Techniques for an Electric Vehicle Traction System

This paper presents two battery energy management (BEM) techniques for an electric vehicle (EV) traction system which incorporates an indirect field-oriented (IFO) induction motor (IM) drive system. The main objective of the proposed BEM techniques is to regulate the IM’s speed while minimizing the lithium-ion (Li-ion) battery bank state of charge (SOC) reduction and state of health (SOH) degradation. In contrast to most of the existing work, the proposed BEM techniques operate without any prior knowledge of driving profiles or road information. The first BEM technique incorporates two cascaded fuzzy logic controllers (CSFLC). In CSFLC, the first fuzzy logic controller (FLC) generates the reference current signal for regulating the motor speed, while the second FLC generates a variable gain that limits the current signal variation based on the battery SOC. The second BEM technique is based on model predictive control (MPC) which generates the current signal for the speed regulation. However, this work introduces a new way of tuning the MPC input weight using battery information. It features a fuzzy tuned model predictive controller (FMPC), where an FLC adjusts the input weight in the MPC objective function such that the battery SOC is considered while generating the command current signal. Furthermore, this work utilizes a model-in-loop strategy comprising a Chen and Mora (CM) battery model and the experimentally obtained battery bank power consumption to estimate the increase in battery bank runtime and lifetime. A real-time implementation is carried out on a prototype EV traction system using the New European Drive Cycle (NEDC) and the Supplemental Federal Test Procedure (US06) drive cycles. The experimental results validate that the proposed CSFLC and FMPC BEM techniques exhibit a lower reduction in the battery SOC and SOH degradation, thus prolonging the battery bank runtime and lifetime as compared to the conventional FLC and MPC speed regulators. Further experimentation demonstrates the superiority of the FMPC technique over the CSFLC technique due to the lesser computational burden and higher average energy saving.

Robust speed control of inverter fed parallel connected induction motors for electric vehicle traction applications

Induction motor is a very versatile machine having a variety of advantages over other types of single-phase AC motors. In the electric vehicle traction system, inverter set up was provided by parallel connection-based induction motor based on sensor. The induction motor is modelled using the estimated parameter instead of the speed sensor to analyse the speed performance characteristics. The proposed system focuses on improving the speed control of induction motors by modified PID controller. The parallel-connected induction motor is considered in this proposed work. The modified PID controller is compared with the conventional controller. The enhanced speed performance for inverter fed induction motors in parallel are analyzed under the parameter variation also in MATLAB/Simulink also compared with conventional methods.

Real Time Li-Ion Battery Bank Parameters Estimation via Universal Adaptive Stabilization

This paper proposes an accurate and efficient Universal Adaptive Stabilizer (UAS) based online parameters estimation technique for a 400 V Li-ion battery bank. The battery open circuit voltage, parameters modeling the transient response, and series resistance are all estimated in a single real-time test. In contrast to earlier UAS based work on individual battery packs, this work does not require prior offline experimentation or any post-processing. Real time fast convergence of parameters' estimates with minimal experimental effort enables update of battery parameters during run-time. The proposed strategy is mathematically validated and its performance is demonstrated on a 400 V, 6.6 Ah Li-ion battery bank powering an induction motor driven prototype electric vehicle (EV) traction system.

Development of autonomous traction system of electric vehicle with electronic differential and fuzzy control system

The article discusses the optimal layout of an autonomous vehicle traction system. In modern society, a special place is occupied by environmental issues. From year to year, a huge amount of statistics is published that reflect the scale of the damage that human products cause to the environment. Today, the main “pest” on the planet is surely cars with an internal combustion engine. At the same time, a complete rejection of motor transport, both in Russia and in the world, is impossible, because the life of modern man is inextricably linked with the constant movements, which are not always possible through urban electric transport. In recent years, many manufacturers of transport systems see the way out in autonomous electric transport systems development, which, in the future, will be able to replace vehicles with an internal combustion engine. In this article traction system variants, choice of electric motor optimal location, and also the control systems analysis which would correspond to requirements to the given technical process are considered.

Implementation of vector control on electric vehicle traction system

BackgroundNowadays, electric vehicle development takes a great attention in vehicle industry and researches, due to demising supplies of fuel, less pollution, and developing many resources of generating electricity as renewable energy and clean resources.ResultsThis research is a part of the Autotronics Research Lab (ARL), applying researches on autonomous and electric vehicles. The main aim of the research is to apply vector control method on traction control system of electric vehicle (mini golf cart) by using two hub motors on the rear wheels while the two front wheels are used for steering; it is assumed that the controlled vehicle is fitted with some equipment which can used in autonomous driving.Simulation results show the output response of speed and torque of the vehicle motors and vehicle speed while the vehicle is moving in a straight line or during steering and also show the fusion between vector control and power steering algorithm.ConclusionsThe system preforms the efficiency, safety, accuracy, and more controllability of electric vehicle traction system, leading to more stability in vehicle speed, lower troubleshoots, and less error in unstable surfaces and bad roads.

Saliency enhancement and torque ripple reduction of wound field synchronous machine by injecting optimum harmonic in rotor shape

This paper presents a new rotor shape design with optimum reverse 3rd harmonic for wound field synchronous machines to effectively enhance the saliency ratio and reduce the torque ripple in a micro electric vehicle traction system. Due to the enhanced saliency ratio, the reluctance torque is expected to be improved. The air gap flux density distribution is reshaped by the new rotor shape method, which benefits the low torque ripple. By contrast, the reverse 3rd harmonic injection is much more suitable than the general 3rd harmonic injection for increasing the effective air gap length along the q-axis for a high saliency ratio. Subsequently, three amplitudes of the reverse 3rd harmonic are studied and it is found that the optimum reverse 3rd harmonic is 1/6 of the fundamental one. To verify the effectivity of the proposed design, the original model and the ICS model are compared. Finally, all the motor characteristics, such as back electromotive force, cogging torque, and electromagnetic torque, are predicted using a 2-D finite-element method with the aid of JMAG-Designer.

Synchronized Switching Modulation to Reduce the DC-Link Current in SRM Drives

Switched Reluctance Machines (SRM) are emerging as a possible alternative in terms of cost and supply stability to rare earth based electric vehicle traction systems. However, because of the huge amounts of energy stored and transferred back and forth between the DC source and the SRM, large DC-link capacitors must be used as buffers, which increases overall costs and size. This paper proposes a novel modulation technique which forces the exchange of energy between phases while decreasing the energy transfer between the DC bus and the SRM. This means lower DC bus currents (capacitor size and cost reduction) and lower Joule-effect conduction losses (better efficiency). The proposed modulation has been validated experimentally in a test bench and compared with the conventional torque-sharing function.

Performance enhancement of electric vehicle traction system using FO‐PI controller

This work improves the performance of an electric vehicle (EV) traction system by using non-linear fractional-order proportional–integral (FO-PI) controller. The functionality of FO-PI controller is benchmarked against integer-order proportional–integral (IO-PI) controller. A 400 V, 6.6 Ah Li-ion battery bank is designed to power an indirect field-oriented induction motor driven prototype EV traction system. The appeal of this study is to reveal the simplicity, robustness, and effectiveness of FO-PI speed regulator for EV traction system. The efficacy of FO-PI speed regulator for EV applications is validated through rigorous experimentation. The FO-PI controller due to its non-linear nature proves to be more robust and effective under variation of a system's parameters and external disturbances as compared to IO-PI controller. Furthermore, the experimental results show that FO-PI control strategy provides higher torque per amp output while maintaining better voltage and state-of-charge profiles of the Li-ion battery bank.

Failure‐mode analysis of modular multilevel capacitor‐clamped converter for electric vehicle application

The bi-directional buck/boost converter is being widely used as bi-directional DC/DC converter (BDC) in an electric vehicle (EV) traction system owing to its simple topological configuration. The major drawback of this configuration is in the event of failure of any of the power semiconductor devices and the power supply to the load will be interrupted. To overcome the above drawback, this work proposes a modular multilevel capacitor clamped converter (MMCCC) for EV application employing battery and ultracapacitor (UC) as energy storage sources. The battery-ultracapacitor (UC) combination provides better acceleration capability during high power demands and efficient energy recovery during regenerative braking. The design, control, and failure-mode analysis of MMCCC are discussed in detail to showcase the merits in terms of conversion gain, modularity, and reconfiguring capability under fault conditions. The high conversion gain owed to the modularity of the topology ascertains optimal stacking of UC thus reducing the weight and cost. Simulation is performed in MATLAB/SIMULINK environment, and hardware prototype is fabricated to validate the simulation results.

Power Flows in Compound Transmissions for Hybrid Vehicles

Hybrid electric vehicle (HEV) traction systems are the most promising technologies being characterized by high performance, high fuel efficiency, low emissions and long operating range. Significant improvements can be achieved equipping transmissions with variable transmission ratio such as power-split transmission and a compound power-split electric continuously variable transmission (eCVT). These systems have been introduced to improve vehicle global efficiency since they can maximize the efficiency in different operating conditions. Optimal design and control of these systems leads improvements in vehicles performance and mathematical models, which support the preliminary design phase, can play a key role in this field. In this work, the internal power circulations of “four-port-mechanical-power split device are determined through a dynamic analysis.” Finally, the efficiency of the compound transmission is analytically evaluated, assuming that the overall losses are linked to the eCVT variator.

Operations of electric vehicle traction system

Operations of electric vehicle traction system

Modelling and Control by Neural Network of Electric Vehicle Traction System

Modelling and control by neural network of hybrid electric vehicle traction system is presented in this paper. The electric drive is composed by a battery bank and an ultracapacitor connected in parallel through bidirectional DC converters and a Brushless DC Motor driven by a three-phase inverter. In the electric drive control loop is implemented a NARMA neural network. The mechanical model comprises a gearbox and a model of the road-wheel friction force and vehicle aerodynamics. All the masses and inertia are expressed relative to the rotor of the motor. The model is studied by simulations with two driving cycles and an assessment of the available energy from regenerative braking is performed. The percentage of recycled energy from regenerative braking is assessed.DOI: http://dx.doi.org/10.5755/j01.eie.24.3.20974

Investigation of DC-Link Voltage and Temperature Variations on EV Traction System Design

DC-link voltage and temperature variations are critical issues when designing an electric vehicle (EV) traction system. However, systems are generally reported at fixed voltage and temperature and may not, therefore, be fully specified when considering the variation of these parameters over full vehicle operating extremes. This paper presents an assessment of power-train options based on the Nissan Leaf vehicle, which is taken as a benchmark system providing experimental validation of the study results. The Nissan Leaf traction machine is evaluated and performance assessed by considering dc-link voltage and temperature variations typical of an automotive application, showing that the system lacks performance as battery state of charge decreases. An alternative traction machine design is proposed to satisfy the target performance. The vehicle power-train is then modified with the inclusion of a dc/dc converter between the vehicle battery and dc-link to maintain the traction system dc-link voltage near constant. A supercapacitor system is also considered for improved system voltage management. The trade-offs for the redesigned systems are discussed in terms of electronic and machine packaging, and mitigation of faulted operation at high speeds.

Sensorless Fault-Tolerant Control of an Induction Motor Based Electric Vehicle

This paper describes a sensorless fault-tolerant control (FTC) for a high-performance induction motor drive that propels an electric-vehicle (EV). The effect of the fault on the induction motor (IM) can be modeled by an exogenous signal from a stable autonomous system. An additive term is added to the nominal offset and serves to control the effect of the defect (FTC aspect). The proposed sensorless FTC for IM is realized in presence of both rotor and stator electrical faults. Consequently, the extended kalman filter (EKF) is proposed to estimate the rotor flux and the rotor speed using the measured stator currents and voltages. Therefore, a classical EV traction system is studied using an induction motor drive. Indeed, the induction motor based powertrain is coupled to DC machine-based load torque emulator taking into account the electric vehicle mechanics and aerodynamics. Simulation and experimental results confirm widely the feasibility and the effectiveness of the proposed FTC of IM based SMC in the electric vehicle application.

PWM Carrier Harmonic Iron Loss Reduction Technique of Permanent-Magnet Motors for Electric Vehicles

This paper investigates a method to increase fuel economy of motors for an electric vehicle (EV) traction system. The low-torque region of an EV motor is frequently used in everyday urban driving and in fuel economy measurement. Pulsewidth modulation (PWM) carrier harmonic iron loss accounts for a high percentage of total loss for EV motors in this region. This paper reveals the relationship between phase current and carrier harmonic iron loss for a permanent-magnet synchronous motor (PMSM) in the low-torque region. Thus, a novel carrier harmonic loss reduction technique is proposed and applied to two sets of three-phase windings for a concentrated winding PMSM. The loss is successfully reduced in a 70-kW EV motor as well as a two-dimensional finite-element method (2-D-FEM) calculation. The efficiency of the developed motor is calculated and compared with that of a conventional motor in the JC08 mode driving cycle.