Design and Comparison of Two Fault-Tolerant Interior-Permanent-Magnet Motors

The aim of this paper is to design and investigate two fault-tolerant interior-permanent-magnet motors for high reliability operation. The first one is the spoke type, while the second one has V-shape magnets embedded in the rotor. The structures and features of both motors are presented and the optimal designs are performed. The electromagnetic performances, such as dq-axis inductances, torque, flux weakening, and partial demagnetization, are investigated and compared. In order to calculate the dq-axis inductances accurately and segregate the torque components, the frozen-permeability method is adopted. Additionally, a method to obtain the maximum flux-weakening speed is introduced. Moreover, the partial demagnetization performances of both motors are evaluated under no-load, on-load, overload, and short-circuit conditions. Also, the fault-tolerant capacities of both motors are compared. Finally, both motors are built for exemplification. The analysis is confirmed by experimental results.