PM Halbach Arrays in Motors: Loss Reduction and Performance Improvements

Halbach array configurations represent a common choice in high-performance electrical machines, since a stronger magnetic field is generated for the same Permanent Magnet (PM) volume. Hence, higher torque is developed, and the power density is enhanced. This paper investigates methodologies for reducing the PM losses in Halbach arrangements. A high power density propulsion motor is considered as a case-study and by using Finite Element (FE) software, sensitivity analyses are performed on the main design parameters. Strategies for loss reduction and performance improvements, in terms of torque ripple, total harmonic distortion, efficiency and power density, are investigated and proposed. The effectiveness of axial and radial segmentations, PM edge shape, and semi-magnetic slot wedges are evaluated. Finally, recommendations are made for designing a PM Halbach array.