Nonlinear torque control using the effect of salience in a synchronous motor

A linearisation of the model is proposed for control of a salient-pole synchronous machine. Unlike classical modelling, it makes no a priori hypothesis on the relative orientation of the stator and rotor fields. This linearisation enables control laws to be written which, using the effect of salience in the generation of torque, optimise the efficiency of the machine and also increase the maximum value of instantaneous torque. Results of simulation are presented for a machine with sinusoidal flux distribution. These are compared with the results for nonlinear control where the “direct” current component (i_d) is maintained at a null value