Analytic Optimization of the Halbach Array Slotless Motor Considering Stator Yoke Saturation

Hybrid subdomain analysis is utilized to optimize the design of a high-speed compressor motor. Permanent magnets (PMs) are arranged in Halbach array and bounded by a carbon fiber sleeve. The stator core does not have a slot structure, so that it is advantageous in reducing the iron loss. Since the core saturation takes place, magnetic equivalent circuit (MEC) is used to find the permeability depending on the flux density of stator yoke. Furthermore, since the core is not infinitely permeable in the subdomain analysis, the solution is obtained in the whole subdomain regions: shaft, PM, air gap, coil, and stator yoke. The results of hybrid analysis are compared with those of finite-element analysis (FEA). Very close matching results are obtained in the flux density and torque even under yoke saturation. The stator yoke height is optimized against the rotor outer radius so that torque, power density, and efficiency are maximized, while stator outer radius, stack length, and coil area are fixed.