Investigation of direct torque control and torque sharing function strategy for switched reluctance motor applications

Applications of switched reluctance motors (SRMs) are limited due to their high torque ripple that caused by the doubly salient motor structure and unbalanced electromagnetic torque. In this paper, two methods are presented to eliminate the torque ripple, including direct torque control (DTC) method and torque sharing function (TSF) strategy. The fundamental theories of the two control schemes are analyzed in detail and their schematic diagrams are illustrated for comparison. To verify and compare the two control methods, the simulations of the motor system based on a 150 W, three-phase 12/8-pole SRM are carried out by employing an asymmetrical half-bridge converter topology. The results show that the actual torque can track the reference torque quickly and the torque ripple can be reduced effectively. The responses to changes of load torque and speed are also discussed in this paper. From the comparisons, it shows that the TSF method can produce more smooth torque for torque ripple reduction without prior-knowledge of the flux characteristics of the motor.