Performance Analysis of a Flux-Concentrating Field-Modulated Permanent-Magnet Machine for Direct-Drive Applications

This paper presents a field-modulated permanent magnet (FMPM) machine using spoke-magnet-array outer rotor for direct-drive applications. The operating principle with detailed theoretical derivation is analyzed to reveal the evidence for high torque capability of the proposed machine, just due to the utilization of effective harmonic flux adding to the contribution of air-gap fundamental flux for energy conversion. Using the finite element analysis, the performance characteristics of the proposed machine are assessed and compared with permanent magnet synchronous machine counterparts to verify the theoretical analysis. A prototype machine is also fabricated for experimental validation of the proposed machine. The analytical discussions also form an important foundation for research in various high-performance FMPM machines.