Research On Fault Tolerant Control Of Six-phase Permanent Magnet Synchronous Motor Based On New Reaching Law

In order to solve the problem of complex maintenance of three-phase motor equipment and out-of-control problems in sudden situations,multi-phase motor has become an important direction of the motor industry in recent years.As the core content,fault-tolerant control of multi-phase motor is the key factor to ensure the stable operation of the system.The fault-tolerant control system of six-phase permanent magnet synchronous motor studied in this thesis,with the redundant phase number of the motor,will use fault-tolerant compensation control algorithm to resume operation when the motor fails.Without vicious events that lead to sudden shutdowns,it is very suitable for the stable aerospace,nuclear power plant,military and other fields.In this thesis,combined with the characteristics of fault-tolerant control of six-phase permanent magnet synchronous motor,the study is included in the following aspects:Firstly,a six-phase PMSM control system is built by MATLAB/ Simulink.In the two-phase synchronous rotating coordinate system,id = 0 control is adopted,and the double closed loop in the motor control system is adjusted by PI control.The transformation matrix from six-phase stationary coordinate system to two-phase rotating coordinate system is derived,the six-phase PMSM mathematical model with nonlinear,multi-variable and flux cross-coupling is decoupled,and the working principles and structure characteristic of the six-phase permanent magnet synchronous motor stator windings are described.Secondly,the amplitude and phase of the residual phase current after phase loss are changed to achieve the effect of fault tolerance compensation,provided that the resultant magnetomotive force before and after the phase loss of the motor stator winding is equal.This thesis studies the magnetomotive force of six-phase permanent magnet synchronous motor with one-phase and two-phase stator winding open-circuit faults(orthogonaland non-orthogonal),and switches to the current hysteresis control and the magnetomotive force compensation after the fault.Then,the sliding mode control(SMC)is combined into the six-phase PMSM fault-tolerant control system,and a new approach law is designed for the sliding mode buffeting problem,which can weaken the chattering and improve the speed of approaching the sliding mode surface.In order to reduce the influence of the internal parameters and external disturbance of the six-phase motor and improve the dynamic performance of the fault-tolerant control system,asliding mode speed controller is designed based on this method.The stability of the closed-loop control system is verified by using Lyapunov function,and the superiority of the control performance is verified by simulation.Finally,on the basis of the above studies on the fault-tolerant control system of six-phase permanent magnet synchronous motor,the SMC speed controller mathematical model is set up in MATLAB\Simulink,the six-phase PMSM fault-tolerant control system is set up,and the simulation waveforms of the fault-tolerant control system under sliding mode control and PI control are compared and analyzed.