Ferrite assisted synchronous reluctance machines: A general approach

A general approach to the design of high performance ferrite-assisted synchronous reluctance motors is presented. Reference is made to a rectified rotor structure, with multiple flux barriers, designed to optimize the performance and the exploitation of the PM material. The key design issue of de-magnetization is analytically investigated, pointing out the maximum allowed current loading, depending on temperature and machine dimensions. Such current limit is then compared with the one imposed by the thermal constraint. The analysis shows that low and medium size machines tend to be robust against demagnetization, while larger machines are more at risk. The theoretical analysis is confirmed by finite-elements via an example machine design.