Research On Key Technology Of EPS Control System Based On PMSM

In this thesis, the basic characteristics of the electric power steering system are introduced and analyzed, and the assisted motor that is very important for this system is researched further. The mathematical models of PMSM are built in several commonly used coordinate systems, and the relationship of these systems is discussed. The control technology of PMSM are presented in detail, and the vector control technology which is one of them is employed.The advantages and disadvantages of many dictation methods are analyzed, and the system for detecting rotor position based on the principle of rotating transformer, which is proved to reliable with high precision by test, is designed, for the point of detecting rotor position which is very key for vector control technology. The theory of two methods of detecting current is discussed, and a kind of project for detecting high current is raised according to the requirement of EPS.The controller of EPS is devised based on STM32F103ZET6, according to the characteristics of EPS and the demand of hardware in the system for PMSM. In this paper, the principle of hardware circuit which includes the torque signal acquisition circuit, the vehicle speed signal acquisition circuit, the CAN communication circuit, the motor drive circuit and the motor angle sensor circuit, and so on, is recommended. In addition, the problem of heat dissipation of electronic control unit is researched.Finally, some software program, which consists of the main program module, the torque signal acquisition program module, the speed signal acquisition program module, the PID control program module and motor control module, are developed. The bench test for the control program of PMSM is conducted to verify that the control software and the circuit designed are reliable and feasible, which also can be turn out are satisfied for the function of EPS by real vehicle test devised for controller.