Research On Key Techniques Of Motion Control System For Electric Vehicles

With the advantages of no pollution emissions and low noise, electric vehicles (EV), which integrate in lots of high-tech, are creating a revolution in the world auto industry. But the motion economical,reliability and safety of EV are demand a high level performance of motion control system. To solve this actual problem, by analyzing the EV's practical run and environment condition, this paper presents an effective method, which can satisfy the requisition of motion control, and explores the key techniques of the method's engineering practice. The paper's major work, results and conlusions:The structure and running characteristic of the EV's motion system were analysed, establishes the dynamic mathematical models of the EV, and studies the related basic theories of motion control. The motion control system for EV based digital signal processor is designed by combine several success projects in the field of automatic control.The detection methods for the EV's motion system are studied. The detection hardware structure of the EV's motion control system is designed based on digital signal processor (DSP), and the software algorithm is programmed. The experiment results show that: the hardware structure of detection system is reasonable and precisely to meet the need of EV's motion detect. From the principle of the detection, AC sampling methods and the hardware realizing schemes, the errors of the detection system are studied, the cause and the quantity grade of each major error are analysed. Then, a method which combines frequency measurement by hardware with correction by software is presented to realize synchronous sampling. And many improved approaches of reducing or correcting the corresponding errors, such as adopting deviation cumulative increment method to optimize sampling period, are presented in order to raise the detect precision.The paper studies the control algorithms and practical methods for EV's motion control. The key points of the method about judging the voltage vector sector by rapid geometric method are discussed. Meanwhile, the simplified calculating formulas of switch vector's action time and the zero vector' arranging sequence are given. From the view of engineering practice, the paper designs the hardware structure of the motion control system by apply CPLD techinology successfully, simplify the hardware structure and the control algorithms and programme the related control sorftware.An indirect measurement method based on electrical parameters is presented for measurement output torque of EV's motor driver, the results of simulations and fieldwork show that the method is precise and stable, and its precision is not affected by the interferential factors such as machine vibration and pollution. The theories and realizing means of the dead-beat control algorithms were analysed in detail. The design calculations of several important parameters in EV's main driving power circuit are analysed, such as the selection of power switch devices, and so on.The experiment results show that the proposed method for the EV's motion control system is right and effective; the key techniques of engineering practice are practical and feasible.