Investigation of pole and slot numbers in axial-flux PM BLDC motors with single-layer windings for electric vehicles

Axial-flux permanent-magnet brushless-dc (PM BLDC) machines with concentrated windings are excellent candidates for direct drive applications regarding their torque-density, efficiency and required size. They can be placed in the wheel of electric vehicles as direct drive motors to eliminate mechanical power transmission system and increase efficiency. Choice of pole number and slot number has dominant effect on machine performance. In this paper an extensive investigation of axial-flux PM BLDC machines having different pole and slot combination has been carried out. As axial-flux machines are three-dimensional electric machines, three-dimensional finite-element (3-D FE) analysis is used to achieve the performance of axial-flux machines accurately.