Design and Analysis of Permanent Magnet Motor with Movable Stators

Permanent-magnet motors are widely used in-wheel motors of electric vehicles and hybrid vehicles. Based on a movable stator design, this paper presents a new type permanent-magnet motor, whose torque can be adjusted in order to meet different driving requirements. The stator geometry is varied by means of changing movable stator positions. Accordingly, the air-gap length in permanentmagnet motors is changed so that torque can be adjusted. To derive an analytical model, Fourier series expansions are employed to formulate air-gap geometry variation. The analytical model is validated by finite element numerical results. Concerning motor torque variation capability achieved in this study, the ratio of the largest vs. the smallest torque is 2.3.