Analysis of detent force in a discontinuous primary type permanent magnet linear synchronous motor

Discontinuous primary permanent magnet linear synchronous motor (DPPMLSM) has many merits in long-stroke transportation, including vertical, horizontal, and slanted model system, however, detent force of DPMLSM is particularly troublesome requiring positioning accuracy specially at low speed region as well as of position control and is different from short primary type and short secondary type PMLSM. The paper analyzes detent force of DPPMLSM and using finite element method (FEM) and indirect detent force method. The end component and slot-tooth component of detent force in the single long secondary type PMLSM at the end outlet is investigated, which is base of analysis of DPPMLSM detent force. DPPMLSM detent force is attained by superposition method. An effective technique of reducing the end component of detent force was modified end teeth shape using the node shifting technique and niche genetic algorithm. The waveform of DPPMLSM detent force at the outlet is ultimately close to sine-wavelike and modifying the end section of primary at both ends is very valid technique to reduce detent force. The conclusions are benefit to analyze DPPMLSM operation performances and design the machine.