Loss study of a dual-air-gap axial flux permanent magnet machine.

This paper presents the loss analysis of a dual-air-gap axial flux permanent magnet machine for a flywheel energy storage system. Losses in iron-core and permanent magnets caused by both space harmonics and time harmonics are respectively analysed using a three-dimensional finite element method. The effect of skew of magnets on machine losses is also taken into account. The analysis is validated by comparisons of calculated losses and measured values on a prototype. A solution to reduce eddy-current losses in the magnets for this machine is also presented. The eddy-current losses in the permanent magnets can be significantly lessened by both circumferential and radial segmentations. [ABSTRACT FROM AUTHOR]