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Description
Linear switched reluctant motors(LSRMs) have received more attention in variable speed drive applications such as urban railway transportation due to their simple structure and minimum use of power switching devices. However, the thrust/power capabilities is not high enough in certain circumstances. To incorporate the merits of simple and robust structure of LSRM and high thrust force density and efficiency of permanent magnet motor, a new linear permanent magnet switched reluctance motor (LPMSRM) with segmented primary is proposed in this paper. The primary of the segmented LPMSRM consists of six individual U-shaped segments; each one has two teeth associated with a PM installed between them. The secondary is simply composed of iron in the core. When none of the coils is excited, the flux generated by the PM is only closed through the U-shaped segment and does not cross the secondary and the gap. So, the no-load cogging force of LPMSRMs is near to zero. The thrust ripple is lower than the conventional LSRMs to some extent. This paper comprehensively evaluates and compares a high-thrust segmented-stator LPMSRM drive with a conventional LSRM drive in terms of static magnetic and dynamic performances. The static magnetic characteristics of a segmented LPMSRM and a conventional LSRM, including flux distribution, phase flux linkage, electromagnetic thrust, are analyzed and compared. The comparative results show that the LPMSRM has better characteristics than the conventional LSRM, such as less iron consumption, higher static and dynamic average thrust production, lower thrust ripple, higher power and thrust densities, higher efficiency, and stronger starting capability.
