Mechanism Investigation of Ring Type Winding in Linear Permanent Magnet Vernier Machine for Improving Force Density

Abstract

The linear permanent magnet vernier (LPMV) machines have been paid more attention in railway vehicles because of its simple structure and low cost. In this paper, the ring type winding (RTW) is adopted in both non-modular and modular LPMV machines to improve force density. The configuration and operating principle of two LPMV-RTW machines are presented. The coil connection and mechanism of RTW are explained and compared with conventional distributed winding (DW) and concentrated winding (CW). The back electromotive force and thrust force are investigated by the time-stepping finite-element method. It is found that non-modular LPMV-RTW machine possesses larger force density than non-modular LPMV-DW machine while modular LPMV-RTW machine has higher force density and utilization ratio of winding than modular LPMV-CW machines under the constant copper loss. Finally, the experiment result is obtained on the prototype, verifying the theoretical analysis.