An analysis and an operating method of switched reluctance motors based on a simple inductance representation

In this paper, a mathematical analysis based on a simple model is carried out. The operating characteristics of switched reluctance motors fed by square waveform voltage are analyzed. Inductance variations with respect to the rotor rotational position is approximated with only a sinusoidal function and a constant. Square waveform voltage is approximated by a fundamental component only. Based on this simple representation, it is possible to analyze operating characteristics mathematically in normalized planes and to derive a general control method. It is found that there exists a particular voltage phase angle which realizes the maximum output per current. It was also found that the maximum output per voltage can be achieved at another particular voltage phase angle. These characteristics are found to be very similar to those of synchronous reluctance motors. As a result of the analysis, an efficient operating method is proposed. These results are confirmed by a 6000r/min., 2 kW prototype machine.