The Method of Design to Reduce the Detent Force of Linear Synchronous Motor

Abstract

Recently, complicated transport system is demanded in the field of factory automation for the reduction of labor in large-scale factory. Linear synchronous motor can produce large thrust force and high speed. Linear synchronous motor was not suitable for the long stroke transport system which needs high positioning precision and high speed simultaneously. The problem in improving the positioning precision is the large detent force arisen by permanent magnet. We analyzed the static thrust and detent force using FEM. Generally, if detent force is enough smaller than static thrust force, high positioning precision can be achieved.
We investigated the mechanisms of detent force generation. As the results, we proved that detent force is generated by the thrust caused by the difference between the magnet end and the tooth. We proved that if the width of the permanent magnet is too wide, the total detent force can be estimated by the superposition of each detent force. As the results of the study, we developed the method of design to reduce the detent force of permanent magnet linear synchronous motor. The detent force is reduced to 0.6 per cent of the maximum thrust force.