Research On Fault Diagnosis Of PMSM Drive System In Electric Vehicles

The increasingly serious energy crisis and environmental issue gradually promote the hot topic,which attracted more and more attention of the government to development new energysaving and environmental-friendly vehicles,electric vehicles(EVs)are one of the research hotspots.Permanent Magnet Synchronous Motor(PMSM)as the key component of EVs,has numerous advantages,such as high power density,high power factor,high torque ratio,etc.Therefore,they are a highly suitable alternative for hybrid vehicles and EVs.However,due to the factors such as its working principles and working environments,an unexpected fault or failure of the PMSM may lead to very high repair or replacement cost,or even catastrophic failure.Therefore,fault diagnosis is greatly needed,which may help in scheduling preventive maintenance to avoid catastrophic failure of the machine.This paper focuses on the stator winding short-circuit fault,demagnetization fault and open-switch fault of PWM inverter in PMSM.Zero Sequence Voltage Component(ZSVC),Sliding Mode Observer(SMO)and SMO based on current residual are presented to diagnose the above three faults,which achieved better diagnostic results.The main work includes:Firstly,In-depth understanding of the structure and working principle of PMSM by reading a large number of domestic and overseas literatures.On the basis of this,summarizing the types of failures that often occur in PMSM,and summarizing the diagnostic methods used for each type of failure,providing the theoretical basis for the research later.Secondly,proposing the method ZSVC to detect the inter-turn fault.Established the mathematical model in healthy condition and fault condition after adding ZSVC,and establishing the corresponding fault indicator to distinguish the faults.For the phase-to-ground fault,establishing the mathematic model after failure.Through simulation and verification,it is shown that the fault diagnosis method can detect and diagnose the fault with higher accuracy.Thirdly,a new sliding mode observer method is proposed to diagnose the demagnetization fault of PMSM.Basing on the change of the flux linkage,establish the state equation after fault.By designing an observer with a new switching function to replace the traditional sliding mode observer,the stability is proved by Lyapunov theory and the results prove that the new sliding mode observe weakens the chattering,and the fault detection of the demagnetion can be well performed.Finally,a sliding mode observer based on current residuals is designed to diagnose the open-switch fault in the inverter,and the theoretical analysis of the situation where two openswitch occur on a single bridge of the inverter is performed.Comparing the observed value with the set current threshold.If it exceeds the threshold,it indicates that the fault has occurred.The feasibility of the theory is verified by MATLAB simulation.