Configurations and control of traction motors for electric vehicles: A review.

Saqib Jamshed Rind, Yaxing Ren, Yihua Hu, Jibing Wang, Lin Jiang

Abstract:In recent decades, worldwide global warming and reduction in petroleum resources have accelerated researcher’s attention to produce alternative sustainable and environmentally clean transportation systems. Electrification of vehicular technology is capable of curbing the environmental pollution problem in an efficient and effective way, due to high efficiency electric motors, development and advancement in the field of power electronic devices, digital signal processing and advanced control techniques.This article presents a comprehensive review on different configurations/ architecture of electric vehicles(EVs) and hybrid electric vehicles(HEVs), traction motors for electric propulsion system and high performance speed sensorless control of traction drive. The basic architecture key components of hybrid vehicle and different power train configurations with respect to applications and limitations are discussed. The integral part of electric propulsion system, traction motor classes for desired operational characteristics and limitations are summarized from a system perspective with the latest improvements. High performance traction motor control techniques are discussed with respect to automotive applications. Finally, speed sensorless control techniques research trends as well as an extensive review on rotor speed estimation techniques for robust and efficient sensorless traction drive control are highlighted.This article provides state of the art key global trends and tradeoff of various technologies with future trends and potential areas of research.

DOI: 10.23919/CJEE.2017.8048407

Development status and trend of electric vehicles in China.

Ming Cheng, Minghao Tong

Abstract:Due to pressures from both energy and environment, electric vehicles (EVs)and their related technologies have experienced considerable achievements in China in recent years. This paper firstly presents the EV development status in China with key statistics including EV market status, mainstream technical indicators, charging infrastructure, and key components (battery, motor drive systems). Then, the developmental driving forces of EVs in China are reviewed and analyzed with an emphasis on government policies such as subsidy rules, research investment, and standards. Finally, the development trend of EVs in China is prospected from aspects of industry, technology and policy, opportunities and challenges, with an expectation that more attention from academia, industry and government will be attracted into the area of EVs.

DOI: 10.23919/CJEE.2017.8048410

Overview and development of variable frequency AC generators for more electric aircraft generation system.

Zhuoran Zhang, Jincai Li, Ye Liu, Yanwu Xu, Yangguang Yan

Abstract:With the development of more electric aircraft (MEA), higher demands for electrical energy are put forward in generation systems. Compared to constant frequency AC (CFAC) generation systems, the constant speed drive (CSD) is eliminated and integrated starter/generator (SG) can be realized in variable frequency AC (VFAC) generation systems. In this paper, an overview of VFAC generators for safety-critical aircraft applications is presented, with a particular focus on the key features and requirements of candidate generators and the starting control strategies.Wound rotor synchronous machines (WRSMs) are typical generators used in VFAC generation systems so far. Meanwhile, hybrid excitation synchronous machines(HESMs) and cage-type induction machines are promising candidates for VFAC generation systems. The generation operation of WRSM is relatively mature, however,the SG technology of WRSM is still full of challenges. As one of the most important issues, the starting excitation methods of WRSM are summarized. An HESM-based VFAC SG system is proposed and developed in this paper. The experimental results show that the starting mode, transition mode and generating mode of the VFAC SG system are realized. The continuous progress of VFAC generation system makes great contributions to the realization of MEA.

DOI: 10.23919/CJEE.2017.7961316

New technical trends on adjustable speed AC motor drives.

Kouki Matsuse, Daiki Matsuhashi

Abstract:Adjustable speed AC Motor drives have been used extensively in modern industry and transportation which calls for electrical and mechanical energy conversion with wide output power range applications. Because of its modularity and scalability,the drive system can be extended to many different application areas. More recently,adjustable speed AC motor drive applications are spreading not only in industry applications, but also sky and the marine. In this paper, after summarizing the history of adjustable speed AC motor drives and applications, the main issues of AC drive technologies are reviewed and investigated in the paper. Technical issues of adjustable speed AC motor drives including its standardization are surveyed and analyzed for more advancement. Finally, the paper provides the latest technical trends on adjustable speed AC motor drives technologies, and discusses the development of high speed high power PM motor.

DOI: 10.23919/CJEE.2017.7961322

Control strategy of wind turbine based on permanent magnet synchr onous generator and energy storage for stand-alone systems.

Fujin Deng, Dong Liu, Zhe Chen, Peng Su

Abstract:This paper investigates a variable speed wind turbine based on permanent magnet synchronous generator and a full-scale power converter in a stand-alone system. An energy storage system(ESS) including battery and fuel cell-electrolyzer combination is connected to the DC link of the full-scale power converter through the power electronics interface. Wind is the primary power source of the system, the battery and FC-electrolyzer combination is used as a backup and a long-term storage system to provide or absorb power in the stand-alone system, respectively. In this paper, a control strategy is proposed for the operation of this variable speed wind turbine in a stand-alone system, where the generator-side converter and the ESS operate together to meet the demand of the loads. This control strategy is competent for supporting the variation of the loads or wind speed and limiting the DC-link voltage of the full-scale power converter in a small range. A simulation model of a variable speed wind turbine in a stand-alone system is developed using the simulation tool of PSCAD/EMTDC. The dynamic performance of the stand-alone wind turbine system and the proposed control strategy is assessed and emphasized with the simulation results.

DOI: 10.23919/CJEE.2017.8048412

Overview of advanced control strategies for electric machines.

Chunhua Liu, Yixiao Luo

Abstract:Control strategies play a key role for operation of electric machines, which would directly affect the whole system performance. In fact, different control strategies have been executed and explored for electric machines, which bring great impacts to industrial development and human society. This paper investigates and discusses the advantages control strategies for electric machines, including the field oriented control (FOC), direct torque control (DTC), finite control set model predictive control (FCS-MPC), sensorless control, and fault tolerant control (FTC).The corresponding control principles, control targets, fundamental approaches,advanced approaches, methodologies, merits and shortcomings are revealed and analyzed in detail.

DOI: 10.23919/CJEE.2017.8250423

A design of single-switch two-stage DC-DC converters with PWM and PFM for off-grid solar power system.

Junkai Zhao, Herbert H.C. Iu, Tyrone Fernando

Abstract:In this paper, a single-switch two-stage DC-DC conversion circuit is proposed for an off-grid solar power application. A photovoltaic(PV) panel powers the load and a storage unit(battery) via the proposed circuit. The battery is designed to balance the supply and the demand of power under different irradiation situations. Based on conventional cascaded DC-DC converters, the proposed design is developed with the single switch technique reducing size, cost and power loss. The control scheme in this design is pulse width modulation(PWM) with pulse frequency modulation(PFM). The PWM module is similar to conventional design except its ramp signal with a variable frequency is provided by a resettable integrator. As a result, the PWM and PFM modules regulate the two stages of the proposed circuit separately with the same switching control signal. In this paper, the modes of operation of the circuit are discussed as well as the control schemes. The design process is described along with the circuit analysis and comparisons with conventional design are made as well. A prototype has been built to verify the proposed circuit with simulation and experimental results.

DOI: 10.23919/CJEE.2018.8327370

A novel design of hybrid energy storage system for electric vehicles.

Xiangyang Xia, Xinxin Zhao, Heqing Zeng, Xiaoyong Zeng

Abstract:In order to provide long distance endurance and ensure the minimization of a cost function for electric vehicles, a new hybrid energy storage system for electric vehicle is designed in this paper. For the hybrid energy storage system, the paper proposes an optimal control algorithm designed using a Li-ion battery power dynamic limitation rule-based control based on the SOC of the super-capacitor. At the same time, the magnetic integration technology adding a second-order Bessel low-pass filter is introduced to DC-DC converters of electric vehicles. As a result, the size of battery is reduced, and the power quality of the hybrid energy storage system is optimized. Finally,the effectiveness of the proposed method is validated by simulation and experiment.

DOI: 10.23919/CJEE.2017.8048411

Distributed and decentralized control architectures for converter-interfaced microgrids.

Tomislav Dragicevic, Dan Wu, Qobad Shafiee, Lexuan Meng

Abstract:This paper gives a summary on recently available technologies for decentralized and distributed control of microgrids. They can be classified into two general categories: 1)power line communication based architectures and 2) multi-agent based architectures. The essential control methods and information sharing algorithms applied in these architectures are reviewed and examined in a hierarchical manner, in order to point out benefits they will bring to future microgrid applications. The paper is concluded with a summary on existing methods and a discussion on future development trends.

DOI: 10.23919/CJEE.2017.7961320

Wide speed range permanent magnet synchronous generator design for a DC power system.

Dongmin Miao, Yves Mallet, Johan Gyselinck, Jianxin Shen

Abstract: A wide speed range permanent magnet synchronous generator (PMSG) system is studied in this paper, including the PMSG design and comparative study on control strategies with a pulse width modulation (PWM) rectifier, the purpose of which is to regulate the DC-link voltage. It is of great importance to study the foregoing DC power system based on the PMSG and PWM rectifier, where vector control (VC) can be implemented and the corresponding field-weakening strategy can be realized by injecting a field-weakening current component without any auxiliary devices. Large machine inductance is desired in order to limit the short-circuit current and the loaded voltage drop.Different control strategies including VC, direct torque control (DTC) and direct voltage control (DVC) are studied and compared with both simulations and experiments.

DOI: 10.23919/CJEE.2017.8048408

Saliency-based position sensorless control methods for PMSM drives - A review.

Guoqiang Zhang, Gaolin Wang, Dianguo Xu

Abstract:Permanent magnet synchronous motor (PMSM) drives are finding expanded use for industrial and domestic drive applications. With the distinguished characteristics such as reduced cost and increased reliability and robustness, position sensorless(self-sensing) control techniques have been good candidates for reliable and costless PMSM drives. The saliency-tracking based techniques further bring the expansion of applications with the extended controllable sensorless operating speed range. This paper presents a review on state of the art techniques for position sensorless drives using the saliency-tracking based methods. The signal injection methods and the future scope of research including the dynamic bandwidth improvement and the acoustic noise reduction are discussed.

DOI: 10.23919/CJEE.2017.8048413

Modeling and analysis of six-phase synchronous motor under fault condition.

G. K. Singh, Arif Iqbal

Abstract:Multi-phase machines (more than three-phase) are rigorously being investigated for various high power applications due to their increased power to weight ratio, increased frequency and reduced magnitude of torque pulsation, and fault tolerant characteristics. Fault analysis of a system is extremely important, not only to understand its operating characteristic, but it is also required prior to the design of suitable control/protective scheme. Therefore, the aim of this paper is not to devise a new mathematical model and control algorithm, but to investigate the behavior of six-phase synchronous motor (SPSM) under fault conditions caused by open circuit (OC) and short circuit (SC) at its input terminals as that has not been reported so far. Some key analytical results have been experimentally verified.

DOI: 10.23919/CJEE.2017.8048416

Magnetomotive force harmonic reduction techniques for fractional-slot nonoverlapping winding configurations in permanent-magnet synchronous machines.

Xiao Chen, Jiabin Wang

Abstract:Compared to conventional distributed winding configurations, the fractional-slot non-overlapping (concentrated) windings exhibit advantages such as short end-winding length, high copper packing factor (particularly with segmented stator structure), low cogging torque, good field weakening capability owing to relatively large d-axis inductance,and better fault tolerant capability due to low mutual inductance. However, one of the key problems of employing concentrated windings in Permanent-magnet Synchronous Machines(PMSMs) is the high eddy-current losses in rotor magnets and/or rotor iron due to the presence of a large number of lower and higher order space harmonics in the stator Magneto-Motive Force(MMF). These MMF harmonics also result in other undesirable effects, such as acoustic noise and vibrations, and localized core saturation which tend to reduce reluctance torque. This paper reviews the current state-of-the-art of the MMF harmonic reduction techniques for concentrated winding configurations in PMSMs,including winding split and shift, delta-star connected windings, multiple 3-phase windings,multilayer windings, uneven turn numbers, and stator flux barriers. Their concepts,advantages and disadvantages are presented and assessed.

DOI: 10.23919/CJEE.2017.8250421

An optimal coordination control strategy of micro-grid inverter and energy storage based on variable virtual inertia and damping of vsg.

Xing Zhang, Fubin Mao, Haizhen Xu, Fang Liu, Ming Li

Abstract:The virtual inertia and virtual damping affect both the dynamic stability of the virtual synchronous generator(VSG) and the configuration of energy storage, but there is a conflict between them while selecting the virtual inertia and virtual damping. An optimal coordination control strategy of micro-grid inverter and energy storage based on variable virtual inertia and damping is proposed to mitigate this conflict. With the integrated optimal constraint of the VSG frequency variation and the energy storage capacity, the virtual inertia and damping of VSG are configured dynamically, adopting linear quadratic optimal control. It can suppress the oscillations of the active power and frequency to improve the stability of VSG and optimally configure the energy storage capacity of VSG simultaneously. The proposed strategy aims to improve the control performance of micro-grid inverter and the system economy. The simulation and experimental results verify the effectiveness of the strategy.

DOI: 10.23919/CJEE.2017.7961324

Predictive field-oriented control for electric drives.

Fengxiang Wang, Xuezhu Mei, Peng Tao, Ralph Kennel, Jose Rodriguez

Abstract:Model predictive field-oriented control (PFOC) is a novel control strategy belonging to the class of finite control set model predictive control (FCS-MPC) for electric drive systems. It is a direct control scheme which minimizes the cost function through the convergence of errors between the given and predictive stator currents. In this paper, PFOC is thoroughly presented and analyzed through its dynamics and steady state operations under wide range of speed and varying torque conditions. In light of PFOC's model based characteristics, its robustness and influence under model parameters' mismatch is also investigated. Experiments are conducted to show these performance and sensitivities.

DOI: 10.23919/CJEE.2018.8409354

A critical topology review of power electronic transformers: In view of efficiency.

Guidong Zhang, Jie Chen, Bo Zhang, Yun Zhang

Abstract: Design of power electronic transformers is a hot research topic and its efficiency improvement is a critical problem all over the world. It is also the largest barrier hindering the application of power electronic transformers in industry. In this paper, the state of power electronic transformers is fully presented in terms of efficiency improvements. It is followed by the efficiency modeling of several typical topologies, and their detailed analysis and comparisons. Then, the corresponding industrial application scope of these topologies is presented, providing theoretical guidance for their industrial applications.

DOI: 10.23919/CJEE.2017.8250420

Active and reactive power decoupling control of grid-connected inverters in stationary reference frame.

Xin Zhao, Liuchen Chang

Abstract:Proportion resonant(PR) controllers are able to achieve zero steady-state error for AC input signals and are widely used for simplifying control systems in the stationary reference frame. However, power decoupling in the stationary reference frame with a PR controller has not been investigated thoroughly. Based on the complex vector model of a grid-connected inverter(GCI), this paper deduces theoretically the power coupling relationship of GCI with the traditional PR current controller. A modified PR controller is provided for achieving the power decoupling, and the design method of the controller is presented. Simulation and experimental results verify that there is coupling between active and reactive power using the traditional PR controller and the proposed method can realize the power decoupling.

DOI: 10.23919/CJEE.2017.8250427

Complete parasitic capacitance model of photovoltaic panel considering the rain water.

Shaolin Yu, Jianing Wang, Xing Zhang, Fei Li

Abstract:Common mode current suppression is important to grid-connected photovoltaic(PV) systems and depends strongly on the value of the parasitic capacitance between the PV panel and the ground. Some parasitic capacitance models have been proposed to evaluate the magnitude of the effective parasitic capacitance. However, the proposed model is only for the PV panels under dry and clean environmental conditions. The dependence of rain water on the capacitance is simply described rather than analyzing in detail. Furthermore, the effects of water are addressed quite differently in papers. Thus,this paper gives complete parasitic capacitance model of the PV panel considering the rain water. The effect of the water on the capacitance is systematically investigated through 3D finite element (FE) electromagnetic (EM) simulations and experiments. Accordingly, it is clarified how the water affects the parasitic capacitance and methods of minimization of the capacitance are proposed.

DOI: 10.23919/CJEE.2018.8327366

Widen the zero-voltage-switching range and secure grid power quality for an ev charger using variable-switching-frequency single-dual-phase-shift control.

Qi Tian, Kevin Bai

Abstract:Compared to conventional electrical-vehicle(EV) on-board chargers utilizing a front-end Power-Factor-Correction(PFC) + an isolated DC/DC converter, which limits the wall-to-battery efficiency to ~94%, a new control strategy using variable switching frequency(VSF) and variable phase shifts frees the PFC stage thereby getting rid of the DC link capacitor and further increasing the system efficiency and power density. The challenge is to secure zero-voltage-switching (ZVS) turn-on for all switches within the full-power range. In this paper a novel VSF single-dual-phase-shift(SDPS) control strategy is proposed, which consists of three control freedoms, i.e., two phase shifts and one variable switching frequency to secure ZVS and achieve PFC simultaneously. ZVS boundaries are pictured and compared among single-phase-shift(SPS),dual-phase-shift(DPS) and the proposed single-dual-phase-shift(SDPS) control.Simulation results and experimental validation through a level-2 EV on-board charger indicate that by using the proposed SDPS control, both ZVS and PFC are secured not only for the heavy load but also for the light load, without sacrificing the system efficiency.

DOI: 10.23919/CJEE.2017.8048414

Fault tolerant control of multiphase multilevel motor drives - technical review.

Zheng Wang, Xueqing Wang, Yibo Wang, Jian Chen, Ming Cheng

Abstract:The multiphase multilevel motor drives are a promising solution for some high-power and high-reliability applications, since they have multiple power conversion routes, a large amount of redundant voltage vectors, higher equivalent switching frequencies and superior harmonic performance. It has great significance to exploit their remedial control strategies in depth to fully utilize their high fault tolerant capabilities.This paper will present an updated technical review of fault tolerant control schemes for multiphase multilevel motor drives. Based on exemplification of the diode neutral-pointclamping three-level (DNPC-3L) inverters and T-type NPC three-level(TNPC-3L) inverters fed asymmetric six-phase PMSM drives, the study is taken for both phase-leg faults and switch faults. Furthermore, the discussion on multiple-switch faults,short-circuit switch faults and switch and leg hybrid faulty conditions are discussed in this paper.