Analysis of hysteresis in resonance-based position estimation of switched reluctance drives

In switched reluctance motors, rotor position information can be extracted from the measurement of position-dependent phase voltage resonances. Due to hysteresis in the magnetic core of the machine, subsequently triggered resonances can exhibit different resonance waveforms, even when the rotor is held at a constant angular position. In order to analyze the influence of hysteresis, a finite-difference model of a magnetic lamination is coupled with a Preisach model. A good correspondence is obtained between simulated and measured time-domain resonance waveforms. The model is used to predict the impact of hysteresis on the sensorless position estimation.