Effects of airgap and magnet shapes on permanent magnet reluctance torque

This paper examines the permanent magnet reluctance torques produced by three different configurations of permanent magnet, airgap, and iron. These configurations are briefly described here as rectangular magnet/triangular airgap, rectangular magnet/sinusoidal airgap, and sinusoidal magnet/sinusoidal airgap. The analysis of the torques is achieved by developing analytical solutions. Equations for magnet reluctance torque are obtained by finding the derivative of the stored field energy with respect to position. The triangular airgap configuration is shown to produce a torque waveform which approximates a triangular waveform, and both the sinusoidal airgap configurations are shown to produce torque waveforms which approximate sinusoids.