Basic research on Permanent Magnet Assisted Synchronous Reluctance Motor with three-dimensional gap structure

A reduction in the use of rare-earth elements in permanent magnets (PMs) is desirable though motors using such rare earth PMs deliver high performance. In order to obtain high torque and high power without rare-earth PMs, a permanent magnet assisted synchronous reluctance motor (PMASynRM) with a ferrite magnet and a three-dimensional (3-D) air-gap structure has been developed. In this paper, the 3-D air-gap structure is demonstrated to be equivalent to shortening the actual gap length to approximately 70% of its original value. Moreover, the effects on the torque and output power of shortening the gap length of the PMASynRM with ferrite magnet are examined.