Comparative study among different rotor topologies of axial flux permanent magnet machines

The optimization of the permanent magnet shape and dimension is crucial for the performance improvement of axial flux permanent magnet (AFPM) machines. In this paper, different magnet shapes are studied and compared based on the performance results. A new magnet shape is also proposed. The cogging torque is considered the most prominent noise source in axial flux permanent magnet (AFPM) machines. Different magnet shapes are analyzed and compared to optimize the efficiency of axial flux permanent magnet (AFPM) machines. Flat trapezoidal pole, curved pole and skewed pole are studied and analyzed and a new shape which is a combination of curved and skewed magnet shape is proposed to further reduce the cogging torque and improve the overall efficiency of axial flux permanent magnet (AFPM) machines. The study focuses on single-sided machines, but the results are valid even for double-sided machines and can be easily extended to other configurations.