Development of Inductor Linear Motor for High-Speed Drive

Abstract

A Magnagap linear motor (MLM) is a type of inductor linear motor in which a permanent magnet is not mounted on the stator. As a result, for applications with a long stroke requirement, a MLM is magnet-saving compared with an iron-core linear motor, which is a type of permanent-magnet linear synchronous motor (PM-LSM). However, in the past, for the same power supply voltage, a high-speed drive was difficult to realize for a MLM compared to a PM-LSM.  This paper discusses the development of a MLM for a high-speed drive. We clarified the advantage of the electromagnetic gear reduction ratio from the thrust principle and examined the most suitable combination of a coil, a permanent magnet, and inductor teeth that could realize both a high-speed drive and high thrust. A Halbach magnet array and grain-oriented steel are applied for high thrust, and a sub-magnet in the mover is applied to reduce the cogging force. Using a prototype, we verified the high-thrust high-speed drive, the reduction in the cogging force, and the amount of permanent magnet used.