International Journal of Electric and Hybrid Vehicles (15 papers in press)
State of health estimation for 18650-type lithium battery based on D-UKF
by Qiuting Wang, Yinzhu Jiang
Abstract: This paper considers an accurate estimation method of State of Health (SOH) for the 18650-type lithium battery. An improved battery model combined with electrochemical characteristics and equivalent circuit model is established. In our study, Double Unscented Kalman Filtering (D-UKF) algorithm is proposed to calculate the internal resistances and battery SOH in the same time. The features of our new method are the derivation of an SOH estimation model based on the Ohmic resistance, and the Ohmic resistance is identified online based on the UKF algorithm. The experimental results indicate that our new battery model considers the different values of the battery internal resistances under different working condition (such as different voltages, different currents and different temperatures). Besides, our study verifies the performance and feasibility of new estimation method based on D-UKF. This new algorithm has a practical value for further study of other electrical vehicle systems.
Keywords: 18650-type lithium battery; D-UKF; Ohmic resistance; state of health; SOH;
Magnetic flux analysis and performance test of permanent magnet and claw-pole electromagnetic hybrid excitation generator for electric vehicle range extender
by Xueyi Zhang, Qinjun Du, Shilun Ma, Wenjing Hu, Huihui Geng
Abstract: The hybrid excitation generator (HEG) has a tangential permanent magnet (PM) and claw-pole electromagnetic parallel combined rotor and a fractional-slot winding stator, which reduces the stator core eddy-loss and the armature winding copper-loss. By establishing the equivalent magnetic circuit model of each part of the HEG and analysing permeance influence factors, magnetic isolation measures are taken to reduce flux leakage and improve output efficiency. The designed electromagnetic coupling regulator controller can ensure stable voltage export from the HEG in a wide range of speed and load state by changing quantity and direction of excitation current to adjust the size of the air gap magnetic flux density. A performance test is done and results show that the output voltage is relatively stable. So the HEG can provide electric energy to battery and electrical equipment of vehicles.
Keywords: tangential permanent magnet; claw-pole electromagnetic; parallel magnetic circuit; hybrid excitation; generator; electric vehicles; range extender; electromagnetic coupling regulator controller; magnetic flux analysis; magnetic field simulation.
Research on torque distribution of distributed driving electric vehicle based on fuzzy control
by Wu Xiaogang, Zheng Dianyu
Abstract: For a distributed drive electric vehicle power system based on the wheel hub motor, on the basis of its mathematical model, this paper proposes a torque distribution strategy based on a fuzzy control algorithm, in order to improve the driving wheel hub motor work efficiency and reduce energy consumption to distribute drive and brake torque. The simulation results show that, compared with the rule-based torque averaging method, the fuzzy control torque distribution optimisation algorithm is applied to the Chinese passenger vehicle urban road driving condition and NEDC driving conditions. Compared with the rule-based method of torque average assignment, the energy efficiency of the dynamic system is respectively increased by 16.61% and 19.31%, and the 100 km power consumption is reduced by 1.27 kWh and 2.7kWh by using fuzzy control for torque distribution optimisation.
Keywords: electric vehicle; distributed drive; fuzzy control; torque distribution.
Research on indirect detection of rotor position for switched reluctance motor starting operation
by Yongqin Zhou, Hang Wang, Ningzhi Jin
Abstract: The initial rotor position information of the Switched Reluctance Motor (SRM) is the most critical problem to be solved for motor starting operation. The initial turn-on phase can be determined by pulse injection method, but cannot realise the accurate positioning of the initial angle. In this paper, a method combining the pulse injection method with the inductance model is proposed to estimate the rotor position angle. The method is to inject a high frequency excitation pulse into the phase winding and indirectly calculate phase inductance by response current. Based on the inherent relationship between phase inductance and rotor position, the initial position angle is accurately located by the phase inductance model, and the continuous rotor position information can be estimated when the motor runs at low speed. Finally, the feasibility of the method is proved by theoretical analysis and experimental study, which can effectively improve the starting effect of SRM.
Keywords: SRM; starting operation; rotor position; indirect detection; inductance model; pulse injection.
What works? An ANFIS-based policy evaluation framework for electric vehicle technology development
by Fatih M. Özel, Huw Davies, Peter Wells
Abstract: The application of socio-technical transitions analysis into realms such as future sustainable mobility has revealed the requirement to understand the efficacy of policy measures ex ante. Electrification of the vehicle drivetrain has been promoted as one possible solution to achieve carbon emission and air quality targets. National governments are increasingly forming suites of policy measures to encourage electric vehicle technologies in the transport sector. To evaluate multiple policy measures, a framework based on adaptive neuro-fuzzy inference systems (ANFIS) has been developed and is described here. For data generation, the electric vehicle innovation policies of the European Union, the USA, Japan, Germany, France and the UK were analysed and compared with the actual technology development that was measured with patent filings in those regions. The training and validation of the proposed ANFIS framework shows that the model is able to predict the development of electric vehicle technologies in terms of patent filings. The model is subsequently applied to Austria in a predictive capacity to evaluate three proposed policy scenarios. This paper concludes that the developed framework might play a significant role for assisting EV innovation policy-making by enabling ex-ante assessment the effects of different policy-mixes on the technical change.
Keywords: battery electric vehicles; policy evaluation; socio-technical transitions; ANFIS-based modelling; Austria; sustainable mobility.
Public procurement of electric vehicles as a way to support a market: examples from Sweden
by Jenny Palm, Fredrik Backman
Abstract: Electric vehicles (EV) are increasingly seen as a desirable sustainable solution for the transport sector, and public procurement is often highlighted as one tool to stimulate a market. In this article, we analyse the role of Swedish municipalities in relation to public procurement and especially whether and in such cases how municipalities in Sweden use public procurement as an instrument to enhance a market for EVs. The strategy in both municipalities was to let the municipal organisation act as role models, create buying power and develop a second-hand market for EVs. The strategy to speed up diffusion within the municipal organisation was through information and test-driving and in dialogue with the administration to solve problems that arise. A potential improvement of the diffusion process would be to find ways to share the extra cost of an EV.
Keywords: electric vehicle; public procurement; sustainable public procurement; municipalities; barriers.
Study on the vertical and lateral coupling dynamics control of the in-wheel motor driven electric vehicles under multi-excitation
by Di Tan, Yanshou Wu, Fan Song
Abstract: To study the coupling dynamics control in the vertical and lateral direction of the in-wheel motor driven electric vehicles under the steering input, road and electromagnetic excitation, a 16-degree of freedom coupling dynamic model is given, which has been verified in previous work. To achieve the improvement of the vehicle coupling dynamics, a dynamics controller is designed subsequently based on the active suspension, active front steering and direct yaw control system. The dynamics controller includes a supervisory coordination layer controller and the above subsystem controller with different control algorithm, respectively. Finally, comparative analysis with or without control is carried out to verify the validity of the controller designed in this paper under certain combined excitation conditions. The results show whether the road with high or low adhesion coefficient, the controller developed in this paper is highly effective for the vertical and lateral coupling dynamics of the in-wheel motor driven vehicle. Especially, under the road with low adhesion coefficient, the control effect on the vehicle running stability and path track capacity is more obvious.
Keywords: in-wheel motor; coupling dynamics control; steering; road excitation; electromagnetic force.
Design and simulations of dual clutch transmission for hybrid electric vehicles
by Vu Trieu Minh, Abouelkheir Moustafa, Mart Tamre
Abstract: Dual clutch transmissions (DCTs) refer to double friction clutches; they are designed and operated fully automated in the vehicle shift gearbox. The best advantage of the DCTs is the improvement of the fuel economy because the power flow from the engine to the transmission is always kept in very high friction coefficient and not interrupted. The current six-speed DCTs can provide more than 10% of fuel economy compared with the conventional six-speed automatic gearbox. Therefore, the use of DCTs for hybrid vehicles has drawn attraction for researchers in automotive industries because of the higher energy efficiency and the environmental benefits. This paper develops the concept design of three vehicle models: conventional dual clutch transmission (DCT); conventional hybrid electric vehicle (HEV); and a combined hybrid dual clutch transition (HDCT). Then, three models DCT, HEV, and HDCT are simulated on different standard drive-cycles in city, extra city, and highway. HEV and HDCT proved the superiority on fuel savings in low speeds. HDCT showed a little bit higher energy saving over HEV owing to the higher efficiency of clutches to torque converters. Conclusions and recommendations for the development of DCT, HEV, and HDCT are also drawn.
Keywords: hybrid electric vehicle; dual clutch transmission; hybrid dual clutch vehicle; Matlab simulations.
Analysis of effect of driving motor on electric vehicle dynamic performance
by Wanyou Huang, Guangcan Wang, Mingjin Yu
Abstract: Dynamic performance is the most essential and important performance for vehicles. In order to find influencing rules on Electric Vehicle (EV) dynamic performance, this paper tests and analyses the effect of the driving motor system and transmission gear selection on EV dynamic performance. By taking an AC asynchronous motor with rated power of 32 kW as the research object, tests are performed to analyse the effect of motor torque in a high-speed flux-weakening range, as well as the effect of motor temperature and bus voltage on motor driving torque. Tests are performed to analyse the effect of motor driving torque limit on dynamic performance. Additionally, real vehicle tests are taken to analyse the influence of transmission gear selection on EV dynamic performance. The above research could provide the basis for the matching among EV powertrain key parts, and the basis for the optimised control of EV dynamic performance.
Keywords: electric vehicle; dynamic performance; influencing factor; driving motor system.
Fuzzy logic vector control of an induction motor and a permanent magnet synchronous motor for hybrid/electric vehicle traction Applications
by Scott Cash, Oluremi Olatunbosun
Abstract: This paper presents a fuzzy logic control scheme capable of controlling an electric/hybrid vehicle using a variety of traction motor topologies. The control scheme uses fuzzy logic controllers created in MATLAB/Simulink to control the vehicles speed, the motors current and the motors flux which can be applied to an induction motor or a permanent magnet synchronous motor. A comparison between the fuzzy logic controllers and their PID counterparts performance is also given. The fuzzy logic speed controllers provide comparable accelerator pedal and brake pedal angles to a person controlling the vehicle, leading to realistic vehicle dynamics. The simulations show that the fuzzy logic current and flux controllers can be used on any motor topology and power rating. This control scheme can be used during the design process of a hybrid or electric vehicle without the need for re-tuning whenever the motor configuration changes.
Keywords: field weakening; fuzzy logic; induction motor; PMSM; vector control.
Research on the energy management of a composite energy storage system in electric vehicles
by Meilan Zhou, Zhanhua Liu, Jifeng Feng
Abstract: To solve the problem of power allocation of battery and supercapacitor in the composite energy storage system of electric vehicles, we propose a logic threshold and fuzzy control strategy to arrange battery and supercapacitor to supply the average and peak power to the load, respectively. Based on the simulation software of electric vehicles, we perform simulation modelling to analyse the current of battery, the SOC of battery and the current of supercapacitor. For verifying the feasibility of the control strategy, we set up an experimental platform to study pure electric vehicles during driving and braking. Simulation and experimental results indicate that the composite energy storage system can reduce the charging and discharging times and the current amplitude of the battery, and improve the usage ratio of regenerative braking energy and the mileage of electric vehicles.
Keywords: electric vehicles; composite energy storage; control strategy; test platform.
Factors affecting the intention to buy electric vehicles: empirical evidence from Thailand
by Trin Thananusak, Sirisuhk Rakthin, Thiti Tavewatanaphan, Prattana Punnakitikashem
Abstract: This study used Partial Least Squares Structural Equation Modelling (PLS-SEM) to test the relationships between the five factors (financial factors, infrastructure, performance, environmental concern, and price-premium) and intention to buy electric vehicles (EVs) in Thailand. Our findings suggest that the Thai car buyers pay attention to the performance factor of EVs (e.g., driving range, speed, safety) whilst not being concerned much with the infrastructure (e.g., charging facilities) and the financial factors (purchase price, operation and maintenance costs, resale price) of EVs. Moreover, the individuals environmental concerns affect the decision to own EVs, and Thai customers are willing to pay a price-premium for EVs. However, the price-premium factor could negatively moderate the relationship between the environmental concern and intention to buy EVs. That is, if the price-premium of EVs becomes too high, people with a pro-environmental ethos may be less likely to adopt EVs.
Keywords: intentions to buy; electric vehicles; EV; Thailand; financial factors; purchase price; maintenance cost; infrastructure; car buyers; charging facilities; performance; driving range; environmental concern; conspicuous conservation; price-premium; moderating factors;.
Matching and optimisation of an in-wheel tri-motor powertrain for electric vehicles
by Hongyu Shu, Xingpeng Diao, Yexing Liao, Qiping Chen
Abstract: As an important development direction of electric vehicles (EVs), the in-wheel motor powertrain has advantages of compact structure and flexible control, although there are some serious problems, such as high performance requirements to the drive motor and complex control strategies. To address these problems, a novel in-wheel tri-motor powertrain (IWTMP) is proposed at first, followed by the introduction of configuration and operating principles. Afterwards, vehicle power demand is calculated based on vehicle parameters and dynamic performance requirements, and a statistical analysis for typical driving cycles is carried out before conducting parameters matching for the IWTMP. Next, an optimisation for original parameters is achieved with an objective function of minimum total power of the IWTMP. Finally, a detailed IWTMP EV model is developed in CRUISE, and simulation results indicate that the IWTMP meets the dynamic performance requirements and efficiently reduces the energy consumption compared with an in-wheel single motor powertrain (IWSMP).
Keywords: electric vehicles; in-wheel motor; driving cycles; statistical analysis; parameters matching; optimisation; simulation; CRUISE; dynamic performance; economic performance.
Research on battery data compression method for electric vehicles
by Xiaogang Wu, Xiaoyu Li, Chunbo Zhu
Abstract: The transmission and storage of electric vehicle battery management system data is time-consuming and infeasible, which reduces the efficiency of data transmission and storage. For this problem, this paper presents a method of battery data compression, the pre-compression is to reduce the amount of data and improve the data redundancy and repeatability, and a strategy was formulated that two universal compression methods, Huffman coding and run-length coding, were applied to different battery data. Experimental results show the method of battery data compression can achieve a good compressibility. The battery data compressibility was about 21%.
Keywords: battery data; data compression; pre-compression; Huffman coding; run-length coding.
State estimation method for power lithium-ion battery based on dynamic equilibrium voltage
by Qiuting Wang, Wei Qi, Duo Xiao
Abstract: The state parameters of power lithium-ion battery include the State of Charge (SOC), the State of Health (SOH) and the State of Power (SOP). These three parameters are used to indicate the current remaining mileage, the maximum endurance mileage, and the acceleration performance, respectively. The dynamic equilibrium voltage (DEV) based on electrical characteristics is studied in this paper. The online state estimation problems for battery cells under dynamic working conditions is discussed in depth. We chose the DEV value as the characteristic parameter to estimate the SOC and SOH values online. The main results of our researches are (1) the mathematical model of power lithium-ion battery is established based on the dynamic behaviour;(2) the state space equations are derived to describe the model parameters and the working performance; (3) the SOC and SOH values are estimated accurately, according to only the DEV curve results under all-new state. Our experiments were processed under different temperatures and different ageing degrees to investigate the new model and new estimation method.
Keywords: lithium-ion battery; dynamic equilibrium voltage; SOC; SOH; SOP; online estimation.