Design considerations for the switched reluctance motor

Analytical design equations are developed to predict the performance and to guide the design of the switched reluctance motor (SRM). The use of these analytical equations to trade-off different SRM attributes is discussed. The various approximations and simplifications used in the development of the analytical design equations are justified using results obtained from a detailed computer model of the SRM and by using experimental results from a high power density SRM designed for an aircraft engine fuel pumping application. Comparisons of predicted and measured machine performance parameters for this 90 kW 25000 r/min machine, such as flux linkage curves, back EMF, electromechanical power converted, and inverter voltampere requirements are presented. It is also shown that there exists a fundamental maximum torque density that is attainable with the SRM and an estimate of this maximum torque density limit is given. The power factor for an SRM is defined and the machine parameters that determine its value are presented. This power factor is compared to the similarly defined power factor for an AC machine and found to be smaller.>