Separation of on-load Thrust Ripple of Moving-Magnet Linear Motor Based on Frozen Permeability

In this paper, a separation method of on-load thrust ripple of moving-magnet linear motor based on frozen permeability method is proposed. The traditional linear motor analysis method divides the thrust ripple into two parts: no-load detent force and electromagnetic force fluctuation. However, when the linear motor is under load, the permeability in the magnetic circuit is changed, that is, the detent force under load is not equal to the no-load detent force. Therefore, based on the motor load condition, this paper separates the thrust ripple of linear motor. Firstly, the on-load detent force is analyzed by frozen permeability method and energy method. Then, the expression of motor electromagnetic force is solved by virtual displacement method, and the expression of electromagnetic force is improved. Finally, the change characteristics of on-load thrust ripple is summarized by comparing the components of no-load thrust ripple.