Thrust Ripple Reduction in Ultrahigh-Acceleration Moving-Permanent-Magnet Linear Synchronous Motor

This paper describes thrust ripple reduction in an ultrahigh-acceleration moving-permanent-magnet linear synchronous motor (MPM LSM). The pole pitch of the permanent magnet (PM) is adjusted to reduce thrust ripple because this technique is effective and is easily applicable for many design procedures of PM LSMs. However, in addition to reducing the thrust ripple, this adjustment affects parameters such as the number of driving phases, the average thrust, the mover mass, and the working range. These parameters influence the performance and the usability of linear motors. In this study, the PM pole pitch of an MPM LSM is adjusted. The MPM LSM produces an average thrust of 4030 N, but the ratio of the peak-to-peak thrust ripple to the average thrust exceeds 80%. The influences on the properties of the MPM LSM are numerically investigated and discussed. The PM pole pitch of the MPM LSM is determined based on the numerical analysis and an improved mover whose pitch was numerically determined is fabricated. The improved mover has a light frame and 18 PMs for realizing a high thrust-to-mover mass ratio (thrust per mover mass). The experimental results demonstrate that the improved MPM LSM can generate 4.56 × 103N with a peak-to-peak thrust ripple of 7.04%.