Three-dimensional finite-element-model investigation of axial-flux PM BLDC machines with similar pole and slot combination for electric vehicles

Axial-flux permanent-magnet brushless-dc (AFPM BLDC) machines with concentrated windings are very attractive choices for direct-drive applications due to their high torque-density, high efficiency, and extreme compact construction. Particularly they are suitable to be used in in-wheel electric vehicles. For this purpose two different AFPM BLDC machine topologies with similar pole and slot combination are designed, and cogging torque, winding inductance, output torque, and unbalanced torque exerted on bearing are obtained for the two 3.4 kW motors. High precision three-dimensional (3-D) finite-element analysis is used to achieve the performance of two motor topologies accurately.