Research On Direct Torque Fault-tolerant Control Of Six-phase Permanent Magnet Synchronous Motor

Because of its small torque ripple,high efficiency output power,good fault-tolerant performance and other remarkable advantages,multiphase permanent magnet synchronous motor drive system has been gradually brought into the research field by many domestic and foreign experts in recent years.This thesis takes double Y shift 30° six phase permanent magnet synchronous motor(permanent magnet synchronous motor,abbreviated as PMSM)as research object,and studies direct torque control of normal or faulted operation of motor.First of all,in order to facilitate a better theoretical analysis for the motor system,this thesis establishes the mathematical model of the double-Y-shift 30°six-phase permanent magnet synchronous motor in natural static coordinate system,deduces six phase stationary to two-phase static coordinate system transformation matrix,transformes nonlinear mathematical model of dual Y shift 30°six phase for the decoupling of the mathematical model of six phase.PI controller is designed on the speed ring of the motor,it realizes effective control of the motor speed by adjusting the parameters of the PI controller,utilizes MATLAB/Simulin to build sixphase PMSM control system,verifies its control effect.Secondly,combined switch table and hysteresis comparator,takes stator flux deviation,torque deviation and position of the stator flux sector of the six-phase PMSM with Y shift of 30°as three inputs of the switch table,studies simulation of direct torque control for double Y shift of 30° six-phase PMSM.Simulation data show that DTC has a good dynamic response,and the project is easy to realize operation and control.Thirdly,this thesis conducts an depth study on the phase fault of double-y shift 30° sixphase PMSM stator windings.Different fault-tolerant control methods are adopted for different phase fault forms(F phase fault,BD phase fault,BC phase fault and BDF phase fault),carries out a comparison of pre-and post-fault states of the motor,analyzes and studies current,torque and speed of the switched fault-tolerant control and non-fault-tolerant compensation of the motor after motor failure happening,then verifies fault-tolerant algorithm of DTC.Finally,in order to make the system robust performance and dynamic performance effectively,this thesis designs the sliding mode control system to replace traditional PI controller on speed loop,simulates and verifies rotational speed and torque of six-phase PMSM faulttolerant system for comparing the control performance of sliding mode speed controller and PI controller,simulation experiments show that after speed loop uses a sliding mode controller,system speed adjusting ability has improved,meanwhile,it has stable running.