The Research On Motor Drive System For EV

With the fuel crisis and growing of automobile exhaust pollution, new energy vehicle has became the direction of future development of the car. The renewable energy and non-pollution emission characteristics of pure electric vehicle has became the main development direction of new energy car. Motor driving system, the main components of electric vehicles, which directly has great affect on the popularization and application of electric cars. Therefore, a high function and high-efficiency of motor drive system is critical part for the electric vehicle. This paper has get a deep research on the design of the hardware platform of mini-blade electric vehicle(less than 5KW) and its control system which under the background of Guangxi natural science fund project and Guangxi auto parts and vehicle key laboratory fund project.For the mini-blade electric vehicles operating characteristics and the high performance, high efficiency of speed control requirements of electric automobile motor drive systems, a design of induction motor vector drive system based on rotor flux orientation was been proposed in this paper. The main analysis and research work are as follows:The induction motor was adopted to the design of electric vehicle motor driver system. The working principle and operating characteristics of induction motor were analyzed detailedly. The dynamic mathematical model of induction motor in rotating coordinates rotor flux was established and the voltage, current, flux and torque equation.This paper analyzed the flux observation of induction motor when it is operating, and compared the observation ways of the current-type flux with the observation methods of voltage-type flux. Then the modified voltage type rotor flux observer has been put forward by using low-pass filter instead of pure integral part. So that the dc drift problems can be solved. At the same time, the weak magnetic of induction motor in high speed has been analyzed, and the voltage track weak magnetic method was put forward. On the basis of induction motor vector control model, the simulation of the vector control system will be tested by the toolbox of matlab/simlink. The simulation results has proved the effectiveness of the design of the vector control method.On the basis of theoretical analysis, The motor vector controller of small pure electric cars was designed based on TMS320F28335. The Hardware parts includes control circuit, inverter circuit, detecting circuit and protection circuit, etc. The control software accomplished( desgined) by C language, including the flux estimation function, digital PI regulator and SVPWM occurrence function, etc.Based on the design of the hardware and software platform, this paper also completed the design of the PC software which based on RS232 serial port communication. The software was used to test and debug the hardware controller of induction motor. The simulation and experiments confirmed that the designed induction motor vector drive system of small pure electric vehicles achieved the requirements of the control, which laid a good foundation for the follow-up work.