In order to solve the problem of large normal force of bilateral moving armature permanent magnet linear DC motor, the analytical expression of normal force on permanent magnet was obtained by using Fourier expansion method considering the cog effect. The research shows that the armature current can inhibit the normal force on the permanent magnet, but at the same time it increases the fluctuation of the normal force. The no-load normal force of permanent magnet can be reduced by 440N by decreasing the pole arc coefficient and tooth width. Although part of the thrust performance is lost, the thrust of the linear motor can be compensated under the condition of higher current, and the thrust fluctuation is basically unchanged. The simulation results are basically consistent with the analytical results, which verifies the correctness of the analytical analysis method of normal force fluctuation.

Normal force analysis， Permanent magnet linear ejection motor，Moving armature