Detent Force Reduction of an Arc-Linear Permanent-Magnet Synchronous Motor by Using Compensation Windings

An arc-linear permanent-magnet synchronous machine (AL-PMSM) is a kind of servo machine used for a scanning system to meet the requirements of high positioning accuracy, high response performance, and wide scanning range. To reduce the detent force and increase the travel range of the AL-PMSM, a novel hybrid excited AL-PMSM with a normal armature winding and compensation windings is proposed and investigated. The compensation windings are installed on the end teeth of the primary side. The influence of a compensation direct current is analyzed by a finite element method (FEM). Based on the result of the analysis, a proper compensation current is proposed to reduce the detent force. The result after the compensation is simulated by the FEM. In addition, a combination of primary length optimization and current compensation is proposed, the proper formula for the compensation current is deduced, and the result calculated by the FEM is provided. To reduce the detent force of the travel end, a proper current is supplied into the compensation winding, the detent force during the both end of the travel range is much reduced, so the smooth travel range is increased. Finally, prototypes of AL-PMSM are manufactured and experiments are conducted to validate the proposed compensation method.