Analytical Methods for Minimizing Detent Force in Long-Stator PM Linear Motor Including Longitudinal End Effects

The detent force in long-stator linear motor is caused by open longitudinal ends of permanent magnet mover, which differs from rotary motor and short-armature counterparts. First, the modeling of end magnetic field is established, and then the nonuniformity of magnetic field between edge and middle magnets is analyzed. Based on the corrected factors of air-gap magnetic field calculation, a general mathematical expression of the detent force by energy method and Fourier transform is developed. Finally, a novel method by unequal pole-arc coefficients of edge and middle magnets is proposed, and the optimized pole-arc coefficients combinations are obtained. The effectiveness of the proposed method is verified by finite-element results.