A Slotted Double-Primaries Permanent Magnet Synchronous Linear Motor With a Low Thrust Ripple

This article proposes a double-primaries tubular permanent magnet synchronous linear motor (DP-TPMSLM) with a low thrust ripple composed of two primaries, a secondary, and a flux barrier. For DP-TPMSLM, the odd harmonics in the detent force can be effectively eliminated by decoupling and modulating its cogging and end forces. The pole-slot combination and winding arrangement of the proposed motor are analyzed to realize the electromagnetic properties of the two primaries superimposed on each other. This article selects the 12-slot, 11-pole DP-TPMSLM as a sample, and a subdomain model considering the effects of cogging, ends, and magnetic barriers is developed through coordinate transformations. Subsequently, the structure of the motor end teeth is improved by combining the advantages of the proposed subdomain model and the finite-element method, which effectively suppresses the even harmonics present in the detent force, thus further reducing the thrust ripple of the motor. Finally, a prototype test and control platforms are built, and the experimental results show that the proposed DP-TPMSLM has a low thrust ripple and excellent working performance.