Four-Wheels-Drive (4WD) electric Vehicle (EV) controlled with Direct Torque Control based Space Vector Modulation (DTC-SVM) is presented, where the electrical traction chain was well analyzed and studied from the lith...Four-Wheels-Drive (4WD) electric Vehicle (EV) controlled with Direct Torque Control based Space Vector Modulation (DTC-SVM) is presented, where the electrical traction chain was well analyzed and studied from the lithium battery, the buck boost to the mechanical load behavior. The speed of four wheels is calculated independently during the turning with the electronic differential system computations which distributes torque and power to each in-wheel motor according to the requirements, adapts the speed of each motor to the driving conditions. The basic idea of this work is to maintain the initial battery state of charge (SOC) equal to 70% and the prototype was tested in several topology conditions and under speed. The simulations carried in Matlab/Simulink verified the efficiency of the proposed DTC-SVM controller, and show that the system has more favorable dynamic performance. Results also indicate that this strategy can be successfully implemented into the traction drive of the modern 4WD electric vehicles.展开更多
A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The...A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The front axle and rear axle of the vehicle chassis could rotate simultaneously around their respective center points and cut the turning radius in half at most through specific mechanical chassis structure design and four-wheel electrical drive.It had great potential to reduce wheel traffic damage to field crops if two rear electrical drive wheels can be controlled to follow wheel tracks of two front wheels during self-steering operation.Therefore,firstly,a two-degree-freedom dynamics model presenting this agricultural electric vehicle was constructed.Then,an MPC controller combined with DYC was applied to arrange torques from four wheels to match desired turning angles,direct yaw moments and travel speeds.The simulation results existed small steady error of steering angles below 0.22%as they were set at 5°,followed with yaw moment under 0.17%and velocity less than 1%.Finally,according to experiment results,the vehicle successfully made a working turning radius of 9.1 m with maximum error of 0.55%when desired steering angles were 5°at the speed of 1 m/s and a minimum turning radius of 1.51 m with maximum error of 6.6%when steering angles were 30°at the speed of 0.5 m/s.It verified that the 4WID agricultural electric vehicle could drive autonomously and steady with small self-steering angle error under the proposed control system and has a feasibility to reduce wheel traffic damage during driving and operation.展开更多
Battery is the key technology to the development of electric vehicles,and most battery models are based on the electric vehicle simulation.In order to accurately study the performance of LiFePO4 batteries,an improved ...Battery is the key technology to the development of electric vehicles,and most battery models are based on the electric vehicle simulation.In order to accurately study the performance of LiFePO4 batteries,an improved equivalent circuit model was established by analyzing the dynamic characteristics and contrasting different-order models of the battery.Compared to the traditional model,the impact of hysteresis voltage was considered,and the third-order resistance-capacitance(RC)network was introduced to better simulate internal battery polarization.The electromotive force,resistance,capacitance and other parameters were calibrated through battery charge and discharge experiments.This model was built by using Modelica,a modeling language for object-oriented multi-domain physical systems.MWorks was used to implement the cycle conditions and vehicle simulation.The results show that the third-order RC battery model with hysteretic voltage well reflects the dynamics of a LiFePO4 battery.The difference between the simulated and measured voltages is small,with a maximum error of 1.78%,average error of 0.23%.The validity and feasibility of the model are verified.It can be used in unified modeling and simulation of subsequent multi-domain systems of electric vehicles.展开更多
文摘Four-Wheels-Drive (4WD) electric Vehicle (EV) controlled with Direct Torque Control based Space Vector Modulation (DTC-SVM) is presented, where the electrical traction chain was well analyzed and studied from the lithium battery, the buck boost to the mechanical load behavior. The speed of four wheels is calculated independently during the turning with the electronic differential system computations which distributes torque and power to each in-wheel motor according to the requirements, adapts the speed of each motor to the driving conditions. The basic idea of this work is to maintain the initial battery state of charge (SOC) equal to 70% and the prototype was tested in several topology conditions and under speed. The simulations carried in Matlab/Simulink verified the efficiency of the proposed DTC-SVM controller, and show that the system has more favorable dynamic performance. Results also indicate that this strategy can be successfully implemented into the traction drive of the modern 4WD electric vehicles.
基金This research work was funded by the National Natural Science Foundation of China(Grant No.51975260)Jiangsu Provincial Key Research and Development Program(Grant No.BE2018372),Jiangsu Natural Science Foundation(Grant No.BK20181443)+1 种基金Zhenjiang City Key Research and Development Program(Grant No.NY2018001)Qing Lan Project of Jiangsu Province,the Priority Academic Program Development(PAPD)of the Jiangsu Higher Education Institutions,China.The authors would like to acknowledge the other colleagues of the team for providing assistance in the experiment.
文摘A model predictive control(MPC)approach based on direct yaw moment control(DYC)was proposed to realize the self-steering drive for a newly autonomous four-wheel independent-drive(4WID)agricultural electric vehicle.The front axle and rear axle of the vehicle chassis could rotate simultaneously around their respective center points and cut the turning radius in half at most through specific mechanical chassis structure design and four-wheel electrical drive.It had great potential to reduce wheel traffic damage to field crops if two rear electrical drive wheels can be controlled to follow wheel tracks of two front wheels during self-steering operation.Therefore,firstly,a two-degree-freedom dynamics model presenting this agricultural electric vehicle was constructed.Then,an MPC controller combined with DYC was applied to arrange torques from four wheels to match desired turning angles,direct yaw moments and travel speeds.The simulation results existed small steady error of steering angles below 0.22%as they were set at 5°,followed with yaw moment under 0.17%and velocity less than 1%.Finally,according to experiment results,the vehicle successfully made a working turning radius of 9.1 m with maximum error of 0.55%when desired steering angles were 5°at the speed of 1 m/s and a minimum turning radius of 1.51 m with maximum error of 6.6%when steering angles were 30°at the speed of 0.5 m/s.It verified that the 4WID agricultural electric vehicle could drive autonomously and steady with small self-steering angle error under the proposed control system and has a feasibility to reduce wheel traffic damage during driving and operation.
基金This work was supported by the National Key Research and Development Program of China(No.2018YFB0106204-03).
文摘Battery is the key technology to the development of electric vehicles,and most battery models are based on the electric vehicle simulation.In order to accurately study the performance of LiFePO4 batteries,an improved equivalent circuit model was established by analyzing the dynamic characteristics and contrasting different-order models of the battery.Compared to the traditional model,the impact of hysteresis voltage was considered,and the third-order resistance-capacitance(RC)network was introduced to better simulate internal battery polarization.The electromotive force,resistance,capacitance and other parameters were calibrated through battery charge and discharge experiments.This model was built by using Modelica,a modeling language for object-oriented multi-domain physical systems.MWorks was used to implement the cycle conditions and vehicle simulation.The results show that the third-order RC battery model with hysteretic voltage well reflects the dynamics of a LiFePO4 battery.The difference between the simulated and measured voltages is small,with a maximum error of 1.78%,average error of 0.23%.The validity and feasibility of the model are verified.It can be used in unified modeling and simulation of subsequent multi-domain systems of electric vehicles.
