Thrust Ripple Suppression of Linear Permanent Magnet-Assisted Synchronous Reluctance Motor

The multilayer flux-barrier structure creates strong magnetic saliency in linear permanent magnet-assisted synchronous reluctance motors (PMa-SynRM-LMs). It offers high thrust density with a reduced permanent magnet volume, but it can also produce severe thrust ripple. This paper investigates the secondary structure to balance average thrust and thrust ripple. A sensitivity analysis is first performed. A reduced-order optimization framework that combines sensitivity screening with response surface methodology (RSM) is then used to reduce the number of optimization variables. To further suppress thrust ripple, a modular primary structure with an optimized staggered displacement is proposed, and several modular configurations are compared. The selected configuration reduces the thrust–ripple coefficient from 31.7% to 19.1%, corresponding to a reduction of 12.6 percentage points (39.7% relative), while the average thrust decreases from 302.6 N to 267.7 N (11.5%). A PMa-SynRM-LM prototype is manufactured and tested. The separately measured module back-EMFs provide preliminary experimental support for the electromagnetic model; synchronized series-connected measurements and closed-loop drive tests remain future work.