Estimation of switched reluctance motor losses

A method of predicting switched reluctance motor (SRM) losses under operating conditions inclusive of saturation is described. General expressions for the flux frequencies in different parts of the core are derived. Fourier analysis is applied to decompose the flux waveforms into their constituent sinusoidal components, which are then used in conjunction with the loss characteristics of the core material to estimate the corresponding loss components. The dependence of these losses on the magnitude and waveform of the excitation current, the switching frequency, and the conduction period per phase is investigated for a peaky and a flat-topped current waveform. The maximum losses are shown to occur in the stator core. SRM core losses are found to be proportional to the excitation magnetomotive force (MMF) and not the applied voltage, particularly under saturation. Mathematical expressions for predicting copper losses are also described. Experimental verification on a 6/4 pole laboratory prototype is presented