Research On Torque Ripple Suppression Of Double Salient Pole Permanent Magnet Motor

Double salient pole permanent magnet motor(DMPMM)is widely used in aerospace,transportation,industrial manufacturing and other fields because of its simple structure,high efficiency,high power density,wide speed range and other advantages.However,because the structure of double salient pole permanent magnet motor is double salient pole,the torque of the motor tooth groove is relatively large,which will produce larger torque ripple when the motor is running,affecting the steady-state performance of the motor.Aiming at the above problems,this thesis studies the torque ripple suppression strategy of double salient pole permanent magnet motor.The main research contents are as follows:In this thesis,the working principle of the double salient pole permanent magnet motor is firstly analyzed according to its basic structure,and then the electromagnetic characteristics of the double salient pole permanent magnet motor such as three-phase flux,back electromotive force and three-phase inductance are obtained by finite element simulation software.Then the mathematical model of the motor in the three-phase static coordinate system and the d-q axis coordinate system is constructed based on the physical model of the double salient pole permanent magnet motor.The traditional vector control block diagram of double salient pole permanent magnet motor is established.Then the electromagnetic torque characteristics of double salient pole permanent magnet motor are analyzed by using the air gap field modulation theory.The mechanism of torque pulsation is given.It is concluded that the excessive torque of double salient pole permanent magnet motor is mainly caused by the tooth groove torque.Then the electromagnetic torque characteristics of double salient pole permanent magnet motor are analyzed and the mathematical model of tooth groove torque of double salient pole permanent magnet motor is obtained.Then the motor control strategy was studied,and the control strategy of multi synchronous rotation PI coordinate system was proposed to inject harmonic current to compensate the motor groove torque,and the torque ripple of double salient pole permanent magnet motor was suppressed.Finally,the experimental platform of three-phase double salient pole permanent magnet motor is designed,and the feasibility of the proposed torque ripple suppression strategy is verified by simulation and experiment.Since multiple harmonic current control rings and PI controllers are introduced by injecting harmonic current through multi-synchronous rotation of PI coordinate system,it is difficult to set parameters.Therefore,this thesis combines the model predictive control principle with the mathematical model of double salient pole permanent magnet motor in d-q coordinate system.Two control strategies of model predictive current control and model predictive torque control for double salient pole permanent magnet motor are obtained.In order to restrain the torque ripple of the motor,on the one hand,combining the harmonic current compensation and the model predicted current control,the harmonic current to be compensated is substituted into the model predicted current control cost function to complete the motor groove torque compensation.On the other hand,combined with the groove torque compensation and model predictive torque control,the groove torque to be compensated is directly substituted into the model predictive torque control cost function to complete the motor groove torque compensation.Finally,experimental results show that both control strategies can suppress the torque ripple of double salient pole permanent magnet motor.There are 56 figures,11 tables and 97 references in this thesis.