Modelling a nonlinear variable-reluctance motor drive

The authors present models for a high-power (60 kW) variable-reluctance motor (VRM) and for the GTO-based inverter that excites the motor. One component of the motor model analytically describes the nonlinear magnetic characteristics of the motor, accounting for both spatial and magnetic nonlinearities. Fitting of the general magnetic model to the experimental VRM is based on static magnetic measurements, but the model is shown to do an excellent job of predicting dynamic behaviour up to frequencies where eddy currents have significant influence. Electrical terminal behaviour and torque are based on the analytic magnetic model. Another model component is presented for motor resistive losses and core losses. The accuracy of the motor model is verified experimentally, demonstrating that the model has the ability to predict the drive performance in sufficient detail to allow the development of excitation strategies for the drive