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Comparative Analysis of Coreless Multidisc Axial Flux Permanent Magnet Motors for Electric Propulsion System

The axial flux permanent magnet (AFPM) motor has a compact structure, high power density and high efficiency due to its unique axial magnetic circuit structure, so it is particularly suitable as the motors for electric propulsion system. However, designing a AFPM motor with high torque density and high efficiency is already a task that requires a huge effort, and it will be a huge challenge to further increase the power density. In this article, three multidisc coreless AFPM motors with different topologies are proposed to serve electric propulsion system applications. This article explains in detail topological structure of three motors and the calculation method of the coreless winding factor considering the effects of different wire types, coil side widths, and motor radius. In addition, the no-load back electromotive force (EMF), electromagnetic torque, torque ripple and power density of the three motors are analyzed and compared with the help of the three-dimensional finite-element analysis (3-D FEA). The comparison results show that the three motors have high power density for the requirements of electric propulsion machines.