Investigation of a Novel High Power-Density Spoke-Type Permanent Magnet Synchronous Machine with Inset Halbach PM Array

A novel interior permanent magnet Synchronous machine (IPMSM) combining the merits of both Halbach PM array and spoke-type magnet configuration is proposed in this paper. The proposed rotor topology can enhance the power-density and torque-density by implementing parallel magnetic flux path for Halbach magnets and spoke-type magnets and reducing the inner rotor magnetic flux leakage. Moreover, the magnetization direction of the assisted PM array can be optimized to obtain a sinusoidal airgap flux density distribution for further torque ripple reduction of the machine. The dimensional parameters of a 12s/10p fractional slot concentrated winding PMSM with proposed rotor topology are optimized by global optimization. The electromagnetic performances of a conventional spoke-type IPMSM and the proposed machine are compared including airgap flux density distribution, open-circuit phase back-EMFs, torque characteristics as well as inductance characteristics using finite element analysis.