Loss Mitigation Techniques for a Novel Toroidal Permanent Magnet Motor

This paper analyzes the losses of a high torque density toroidal permanent magnet motor has. The motor has a rotor wrapping around the stator in a circular shape in order to maximize the electromagnetic interaction with in the motor volume. The toroidal motor is simulated using 3D finite element analysis and the results show that the proposed configuration can achieve torque densities higher than radial and axial flux permanent magnet machines. However, it also has high magnet eddy current losses that could potentially limit the machine efficiency and reliability. Several techniques for magnet loss reduction are proposed including magnet orientation, material composition, position, and segmentation as well as winding configuration. These modifications led to a high efficiency - high torque density toroidal motor with only 1.3% of the magnet eddy current loss of the original design.