Design and Modeling of a Novel Permanent Magnet Width Modulation Secondary for Permanent Magnet Linear Synchronous Motor

High-speed linear motor with low thrust ripple is one of the research focuses of high-performance systems. This article proposes a novel secondary topology for permanent magnet (PM) linear synchronous motor (PMLSM) with high speed, to suppress the thrust ripple. PM width modulation secondary adopts several PMs to excite the main magnetic field per pole. The issues from a big pole pitch, which is generally used by high-speed PMLSM, are solved. These PMs have various longitudinal lengths based on the pulsewidth modulation principle, to achieve a magnetic field with excellent sinusoidal features. First, the topology structure of PM width modulation secondary is designed. The analytical model of the main magnetic field excited by PMs in this novel secondary is established, and the electromagnetic thrust is calculated. Furthermore, the influences of PM width modulation secondary on the main magnetic field and thrust properties are analyzed. The comparisons between two PMLSMs employing PM width modulation secondary and Halbach secondary, respectively, are provided. Finally, prototypes are manufactured and tested, to verify the effectiveness of the topology proposed in this article.