Analysis of a new design of single-phase permanent magnet brushless DC motor for low-cost applications

The work described in this presentation is a full analysis of a theoretical model for a novel single-phase permanent-magnet brushless DC (PMBLDC) motor. Overcoming problems of a poor starting torque and reducing the cogging torque has been the focus of this work. This is very difficult to achieve for a single-phase motor, as there are natural pole alignment positions where normally torque is not produced. The design methodology utilizes a number of techniques to achieve these goals, including stator pole asymmetry, rotor and stator pole shaping and air-gap tapering. An accurate 2D finite-element simulation was employed to numerically analyse the magnetic field distribution inside the motor. The results include flux plot visualizations, the back-EMF shape and predictions of cogging and electromagnetic torque characteristics. It has been shown that the cogging torque is 1.3% of the peak electromagnetic torque and the minimum starting torque is 3 Nm.