Research On Design Of Unit Type Cylindrical Permanent Magnet Linear Motor And Thrust Fluctuation Method

Permanent magnet linear synchronous motor(PMLSM)has the dual advantages of permanent magnet motor and linear motor.It has the advantages of small size,fast response,simple structure and broad application prospects.However,due to the cogging effect and end effect of permanent magnet linear motor,the thrust fluctuation of permanent magnet linear motor is large,which affects the performance of the motor.Therefore,the research on thrust ripple suppression of permanent magnet linear motor has very important theoretical and engineering practical significance.The thrust fluctuation of permanent magnet linear motor is mainly caused by the cogging force and the end force.Through simulation analysis,it is found that the cogging force changes in the period of the pitch length and the end force changes in the period of the pole distance.Based on this,a new method of suppressing the thrust fluctuation by series phase shifting of the unit motor is proposed.Through theoretical deduction,it is concluded that the best effect of suppressing thrust fluctuation is the displacement of one-half pitch of integer slot motor and the best effect of suppressing thrust fluctuation is the displacement of one-half pole distance of fractional slot motor.An integer slot cylindrical permanent magnet linear motor is designed,and the unit motor is phase shifted.The results show that the method can effectively suppress the thrust fluctuation and reduce the harmonic content of the thrust;The effects of different displacement distances of integer slot motor on thrust ripple are investigated.The results show that the best effect is to reduce thrust ripple by shifting one-half tooth distance of integer slot motor;The simulation results show that the thrust fluctuation can be suppressed without adding magnetic isolation material,but the effect is not as good as adding magnetic isolation material;The fractional slot cylindrical permanent magnet linear motor is designed,and the unit motor is phase shifted.The results show that the fractional slot motor can effectively suppress the thrust fluctuation and reduce the thrust harmonic content;The suppression effect of fractional slot unit motor on thrust fluctuation under different displacement distances is explored,and it is concluded that the half pole distance of fractional slot unit motor is the best one to suppress thrust fluctuation;Finally,the structure of displacement-free phase of the unit motor is studied.It is found that the displacement processing of the unit motor can ensure that the two units work in the same state,and the output of the motor is large enough thrust.The new method of series phase shifting of unit motor proposed in this paper can effectively reduce the thrust fluctuation of permanent magnet linear motor.It is of great significance to improve the operation performance of permanent magnet linear motor,reduce vibration and noise,and widen the application scope of linear motor.