Comparison of Hybrid PM assisted Synchronous Reluctance Motors

Permanent magnet assisted synchronous reluctance motors (PMa-SyRMs) are becoming popular in applications such as electric vehicles (EVs), refrigerant compressors, bore-well pumps, etc. The main role of PMs in a PMa-SyRM is to saturate the rotor iron bridges and improve the power factor of a conventional SyRM. Hence, limited volume of PMs is sufficient for this purpose. Usually, rare-earth PMs are used in these applications for achieving high performance. However, the prices of rare-earth PMs is increasing everyday. Low-cost ferrite PMs despite being an alternative to Nd-Fe-B PMs have low remanence. On the other hand, Al-Ni-Co PMs have higher remanence and are economically viable. However, they have a steep II-quadrant B-H curve and are thus prone to demagnetization. In this paper, various hybrid PMs based PMa-SyRM are analyzed. 2-D finite element (FE) analysis is carried-out on the these hybrid PMa-SyRMs and the comparison results are presented.