Theoretical aspects of control of synchronous reluctance machines

The author presents a theoretical performance analysis of several control strategies for synchronous reluctance machines which are being fed from a current controlled inverter. The three main control strategies considered have as their objectives to allow maximum rated torque, maximum rate of change of torque and maximum power factor, respectively, from the machine. These control strategies are investigated to determine their limitations and inter-relationships. A technique for `field weakened´ control of the machine is developed. It is shown that the rate of change of torque performance of the control strategies based on constant current angle is poor at lower angular velocities. A control strategy based on having constant current in the most inductive axis of the machine is shown to give better performance under these conditions, and a technique for moving between control strategies is developed