Aiming at the problem that the performance of the permanent magnet synchronous motor drive system will de-crease when the open-circuit fault of the power switching element occurs,a fast diagnosis method for open-circuit fault of the inverter is proposed to improve the safety and stability of the permanent magnet synchronous motor drive system.Firstly,the vector modulus of the three-phase current output by the inverter in the stationary coordinate system is calcu-lated.Secondly,the three-phase current is normalized by vector modulus.Then,the average value and absolute average value of the normalized three-phase current are used as the fault feature quantity and the fault detection variable is ob-tained by calculating the fault feature quantity.Finally,fault diagnosis rules are formulated according to fault detection variables and thresholds.This method does not consider the problem of current mutation.Through MATLAB/Simulink simulation analysis,it is verified that this method can quickly diagnose and locate the 21 open circuit fault types of the in-verter at 2ms after the fault occurs.
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