Design of a Double-Side Flux Modulation Permanent Magnet Machine for Servo Application

Flux modulation machine (FMMs), which operate on magnetic gearing effect, have high torque density and low pulsating torque. Therefore, FMMs are very suitable for servo machines. In this article, based on the specific application in a servo system, a double-side (DS)-FMM, which has permanent magnets (PMs) on both stator and rotor, is proposed and designed. First, the structure and the evolution process of the DS-FMM are introduced. Then, the design optimization is presented, and the effects of main design parameters on torque density, cogging torque, torque ripple, and power factor, which are the most important performance indexes for servo machines, are analyzed. Moreover, in order to ensure the operation safety, the thermal and mechanical verifications are carried out. Besides, the proposed DS-FMM is compared with a regular PM servo machine in terms of torque density, cogging torque, torque ripple, power factor, and so on. Finally, to validate the design of the DS-FMM, a prototype is built and tested. The experimental results coincide well with the theoretical design.