Research On Fault-tolerant Control Of Five-phase Permanent Magnet Synchronous Motor

Nowadays,electric vehicles are becoming more and more popular.PMSM(Permanent Magnet Synchronous Motor)is the driving core of electric vehicles.The high reliability and excellent output performance of the motor control system are particularly important.In this thesis,FP-PMSM(Five-phase Permanent Magnet Synchronous Motor)is applied to electric vehicles,and the surface-mounted FP-PMSM is the research object.The motor works under the working conditions of high inertia,low speed and large torque.Under the working conditions,the drive system of the motor in the non-fault state and the fault-tolerant control system in the fault state are studied.Firstly,the FOC(Field-Oriented Control)and the more advanced FCS-MPCC(Finite Control Set Model Predictive Current Control)are compared and analyzed in the non obstacle state.Then focus on the control of motor in the fault state,and introduces FCS-MPCC into fault-tolerant control of one-phase and two-phase open-circuit,which well suppresses the fluctuation of torque and speed when the motor is open circuit.In addition,EKF(Extended Kalman Filter)is used to estimate the speed when the two-phase open circuit,which further enhances the stability of fault-tolerant control system under the fault state of two-phase open circuit.The research contents of this thesis include:(1)On the basis of analyzing the dynamic mathematical model of FP-PMSM and the working principle of five-phase inverter,the control principles of FOC and FCS-MPCC are studied in detail;The motor mathematical model of FP-PMSM is analyzed and established under the fault state of one-phase and two-phase open circuit.(2)Taking the electric vehicle as the application background,in the normal state of the motor and the one-phase open-circuit state of the main circuit,the fcs-mpcc control and FOC control are theoretically analyzed and compared.and the controllability of FCS-MPCC is verified to be better than FOC control through simulation.In the normal state of the motor,The speed and torque corresponding to FCS-MPCC have better static characteristics and steady-state accuracy;In the open-circuit state,the FCS-MPCC fault-tolerant control has better open-circuit torque and speed recovery capabilities,and better ability to weaken the third harmonic current.(3)The FCS-MPCC fault-tolerant control system in the adjacent two-phase open-circuit fault state of FP-PMSM is studied.In order to further improve the fault-tolerant control performance of the system,the speed estimator of EKF is designed and applied to the FCS-MPCC fault-tolerant control system,which improves the robustness and stability of the two-phase fault-tolerant control system.Through simulation verification,in the non-fault state,FCS-MPCC has faster dynamic response and static characteristics than the FOC system;In the open-circuit state,the single-phase fault-tolerant control system based on FCS-MPCC and the two-phase fault-tolerant control system based on FCS-MPCC that EKF is applied to can effectively restore the open circuit torque and speed,so that the motor can run smoothly and safely in the fault state,which improves the driving safety of electric vehicles.