Influence of design parameters on the starting torque of a single-phase PM brushless DC motor

The starting torque of a single-phase permanent magnet brushless DC motor is investigated, for both radial and parallel magnetization. Finite element analysis is used to assess the relative merits of alternative methods of introducing the required air gap asymmetry, viz. tapered air gap, stepped air gap, asymmetric air gap, and slotted teeth. The predicted results are validated experimentally.