Force Ripple Suppression for Permanent Magnet Linear Synchronous Motor

The force ripple, which is caused by the interaction between permanent magnet (PM) and the iron core, is the main drawbacks of the permanent magnet linear synchronous motor (PMLSM) and will deteriorate the performance of the PMLSM. This paper proposes a control based method to reduce the force ripple. The force ripple that can be predicted by indirect measuring control current of q-axis is compensated by injecting an instantaneous current which is calculated by a displacement periodicity fitting equation using FFT (Fast Fourier Transform) method. Experiment result is reported to prove the effectiveness of the method for high precision motion tracking application.