Design and Analysis of Fractional Pole-Pair Linear Permanent Magnet Machine

Abstract

A novel concept of fractional pole-pair linear permanent magnet machine (FP-LPM) has been proposed recently. It is found that using fractional pole-pair number in linear permanent magnet machine(LPM) could effectively reduce slot cogging force as well as back EMF unbalance. Thus thrust ripple is curtailed which improves its thrust quality and enhances its application potential. However, some issues of FP-LPM still remain unsolved, such as phase split, current phase adjustment, plus structure optimization is different from the traditional topology due to extra auxiliary tooth, etc. This paper contributes to giving a detailed designing methodology including winding arrangement, regulations of choosing slot/pole combination and effective end optimization method of FP-LPM. Thus, this paper can give helpful guidance in designing FP-LPM to satisfy different application demands. Finally, an 18slots/29poles fractional pole-pair linear permanent magnet vernier machine (FP-LPMVM) is designed and constructed using the proposed method and the test results verifies the research conclusions.