Research On Fault Diagnosis Method For In-wheel Motor Driving System

In recent years, the technology of electric vehicle develops rapidly, and severallarge auto manufacturers have gone to the stage of mass production from the stageof researching. The electric vehicle is proposed after the traditional fuel automobilehaving developed maturely, so its technology is also on the rising stage. And theelectric vehicle fault diagnosis technology is one of the main research technologies.In-wheel motor driving electric vehicle is the trend of the development of theelectric vehicle in the future. While it can greatly increases the flexibility of thevehicle control, and also can meet the request of vehicle stability, safety and faulttolerant control due to the increasing number of actuators. In this paper, thebackground was the in-wheel motor driving electric vehicle. In this paper, a faultdiagnosis approach based on sliding mode observer was proposed for finding the in-wheel motor fault. And in the last, the paper proved the possibility of this method inthe actual system.This paper firstly established the vehicle tire model and vehicle dynamicsmodel, and proved the precision of the models using veDYNA, which is the highprecision model of vehicle based on the software of Matlab. Then, the paperanalysed the cause of the precision error.And then the paper went to the main body of the work, the research of in-wheel motor fault diagnosis method. Because some vehicle states can’t be measureddirectly, but were necessary in this fault diagnosis method, a nonlinear observerbased on the vehicle model was first designed for estimating the vehicle states, andcalculating the inputs of the sliding-mode observer according to the estimatedvehicle states. Then based on the wheel model the paper designed the sliding-modeobserver to estimate the unknown input of the wheel, which was the differencebetween the actual output torque and expect torque of the in-wheel motor. Finally, asimulation experiment was carried out in Matlab/Simulink to validate the faultdiagnosis method.Finally, this paper preliminarily explored the actual practice of this method.This paper realized the off-line fault diagnosis of in-wheel motor on single chipmicrocomputer using this method. First the paper discretized the models andobserver, and written the algorithmn in C language. Then the correspondinghardware circuit part and the software programming part were designed. Finally, thealgorithm was run in the designed microcontroller fault diagnosis system, and theresult was contrast with the above simulation results.