Thrust Ripple Suppression of PMLSM Drives Based on Fourier Transform Compensator Cascaded Improved ESO

Permanent magnet linear synchronous motor (PMLSM) has many superior advantages, but the unique structure leads to the large end force. And PMLSM is also affected by other disturbance forces such as the cogging force and friction force. These forces result in the large thrust ripples, which seriously reduce the performance of PMLSM drives. Firstly, the dynamic model and thrust ripple characteristics of PMLSM are analyzed. On this basis, a thrust ripple suppression method based on the Fourier transform compensator cascaded an improved extended state observer (ESO) is proposed. The Fourier transform compensator extracts the amplitude of the 2nd harmonic of the speed ripple, and outputs the feedforward compensation to suppress the detent force in the thrust ripples. The improved ESO observes and compensates other harmonic components. These two parts adopt cascade structure to comprehensively suppress the thrust ripples of PMLSM. Finally, experiments are carried out on a 750W PMLSM drive platform to verify the effectiveness of the proposed suppression method.