Novel design of flux-intensifying interior permanent magnet synchronous machine suitable for power conversion and self-sensing control at very low speed

This paper proposes a new rotor design for flux intensifying, interior permanent magnet synchronous machine (FI-IPM SM) which has similar torque-speed and power capabilities to a traditional flux weakening, IPM SM (FW-IPM SM). Design steps for the rotor structure of the new machine are laid out and discussed to emphasize key design challenges. The proposed FI-IPM SM and a conventional FW-IPM SM with similar torque-speed capability, are used to evaluate performance in power conversion as well as self-sensing capability at very low speed. Finite-element analysis (FEA) is used to evaluate each machine's performance. The proposed FI-IPM SM shows less variation in the saliency when the machine is loaded, leading to a possibility of better self-sensing performance at very low speed as compared to the traditional FW-IPM SM. Experimental results on the efficiency and self-sensing performance of these two machines are presented to verify the design methodology.