Research And Implementation Of The Fault-tolerant Control Strategy For Electric Vehicle Motor Drive System

With the deepening of the global oil crisis and the increasingly serious environmental pollution, Countries around the world begin to realize energy conservation and emission reduction is the main direction of future development of automotive technology, and the development of electric vehicles can effectively solve these two problems. The major car producing countries in the world began to increase electric vehicle research and development efforts to make electric vehicles be popularized as soon as possible.In electric vehicles, the AC motor drive system is the core component, therefore the reliability of the AC motor drive system can directly affect the electric vehicle running safely. The Ac motor drive system is usually composed of motor, inverter, sensors and controllers. In practical applications, poor working conditions, mechanical fatigue and other factors, making every aspect of the AC motor drive system are likely to experience failure, which affects the entire system to work properly, and even lead to system paralysis. Power electronic devices and driving circuit of the inverter section relative to other parts, the failure rate is much higher. The reliability problem has not been effectively resolved. Now redundancy design of power converter is usually used to improve the tolerance of the system. Although this method will not affect the performance of the system after fault tolerance, backup power electronic switching devices in most cases do not participate in operation, resulting in waste.This subject for the inverter in AC motor drive system of electric car, puts forward a simple, effective and low-cost fault tolerant method. Specific work content as follows:This paper first introduces the background and overview of the electric vehicles. Then briefly introduces the AC motor drive system fault detection, isolation and fault-tolerant control method, and the advantages and disadvantages of these methods have been analyzed.Then describes the goal of the this research, and fault tolerant control algorithm is deduced based on the before and after the fault motor air-gap magnetomotive force balance principle. In asynchronous motor, the uneven air gap and the distribution of the winding in different ways will generate space harmonics in the air-gap magnetic field, and switch state of power semiconductor converter components will superimpose time harmonics in the output voltage and current. Space harmonics and time harmonics will affect the result of the derivation of fault tolerant control algorithm. So this article gives a detailed analysis of these two harmonics. Using the mathematical model of asynchronous motor, set up a motor model of the system in simulink,which can be connected to three-phase four wire drive. And use this model to verify the fault tolerant control algorithm.Finally, the paper designed and completed the building of fault-tolerant control experiments platform of the motor drive system. With DSP TMS320F28335as control chip, the Sifang inverter as motor drive module, respectively for a YVP100L2-4,3kW,50hz,7.5A three-phase asynchronous motor made an experimental of fault-tolerant control. The experimental results in the three states of normal operation, trouble-free operation and fault-tolerant operation have been analyzed. The results show that the fault tolerant control algorithm can make the three-phase asynchronous motor continue to stable operation after a fault.