Research On Fault Diagnosis And F Ault-tolerant Control Of Inter-turn Short Circuit In Permanent Magnet Synchronous Motor

Permanent Magnet Synchronous Motor(PMSM)has been widely used in modern industry,aerospace and other fields due to its high efficiency and high power density.PMSM as an electromechanical energy conversion mechanism,if a failure occurs and was not detected in time,the motor itself could be damaged,and the entire electromechanical system will be sabotaged,causing huge economic losses.Therefore,fault diagnosis and fault tolerance control are essential to ensure the stable operation of PMSM.First,the mathematical model of the abc coordinate system and the dq coordinate system in the normal state of the motor was established in this paper.Then the short circuit branch strategy in the short circuit phase is introduced,to establish the nonlinear model of the PMSM under inter-turn short circuit fault.The analysis and calculation of the stator winding resistance and inductance parameters after the fault was emphasized.This model is applicable to both normal and fault states of PMSM,avoided the problem of frequent model shifts during simulation research.Simulation analysis was conducted on the normal and fault conditions of the motor to verify the correctness of the model construction.Secondly,the extraction and analysis of PMSM fault current signal characteristics.The principle of Kalman order algorithm is adopted to extract the third harmonic component of the fault current,and the location of the fault is determined according to the characteristics of the third harmonic amplitude of the fault phase is much larger than the characteristics of the other two phases.The slope of the third harmonic amplitude with speed change curvre is used as an indicator for diagnosing the severity of inter-turn short out faults.A new negative sequence current calculation method is proposed,which extracts the negative sequence current after the tum-to-turn short circuit fault occurs.Combined with BP neural network algorithm,the slope of the curve of the third harmonic amplitude with speed and the negative sequence current are adopted as the characteristic quantities for diagnosing PMSM interturn short-circuit fault.The simulation results show the feasibility of the method.Finally,for the fault-tolerant analysis and fault-tolerant control of PMSM inter-turn short-circuit faults,the corresponding fault-tolerant switching operation mechanism is designed when an inter-turn short-circuit fault occurs.When a turn-to-turn short-circuit fault in the PMSM was detected,if the fault is not easy to repair or the new equipment is cannot be replaced immediately,the fault phase winding will be disconnected,thereby turning the short-circuit problem into an open circuit problem,and then performing fault tolerance control.By using Matlab/Simulink,system modeling and simulation analysis of three different states of three-phase PMSM before and after the fault,and with fault-tolerant control are compared to verify the feasibility of the fault-tolerant control strategy for PMSM inter-turn short-circuit fault proposed in this paper.