Thrust Ripple Reduction of Dual-Side Toroidal-Winding Linear Permanent Magnet Vernier Machine by Unequal End-Teeth Width

The linear permanent magnet vernier machines have attracted more and more attention last several years due to its high thrust density at low speed, which is very suitable for the direct-drive applications. A dual-side toroidal-winding linear permanent magnet vernier machine (DSTWLPMVM) with the unequal end-teeth width is proposed in this paper to reduce the detent force and thrust ripple. The low detent force in DSTWLPMVM is achieved by combination of two single-side detent forces with the opposite phase angle, which is obtained by optimizing the unequal end-teeth width of the primary two-sides. In the proposed machine, the symmetry three-phase flux linkage of the toroidal winding also can be obtained by optimizing the unequal end-teeth width. Therefore, the low thrust ripple of DSTWLPMVM is achieved by optimizing the unequal end-teeth width for obtaining the low detent force and symmetry three-phase flux linkage. The vertical magnetic force in the proposed LPMVM is also considered by finite element analysis (FEA) in this paper. Via optimizing the unequal end-teeth width, the detent force is reduced by 90% while the peak-to-peak thrust ripple is reduced by 69% than that of DSTWLPMVM with the equal end-teeth width, respectively. In this paper, the thermal and PM demagnetization behavior of the proposed machine are also analyzed by FEA.