Multipolar Ferrite-Assisted Synchronous Reluctance Machines: A General Design Approach

The design of multipolar ferrite-assisted synchronous reluctance (FASR) machines is formalized via a two-step procedure. At first, one rectified machine pole is analyzed, and key figures of merit are expressed in equations to derive general guidelines for high-performance designs. Then, rotating machines are modeled as the combination of multiple rectified poles within a stack cylinder having constrained outer dimensions. It is demonstrated that, at a given output torque, the number of poles can be optimized to minimize either the Joule loss or the magnet remanence. The design approach is both finite-element analysis and experimental testing on an FASR machine, rated 795 N · m at 168 r/min. It has been prototyped to compete with a previous solution based on rare-earth magnets, which shows similar performance.