The inherent simplicity and low cost of switched reluctance motors (SRM) make them well suited to many applications. However, high torque ripple is intrinsic in this motor unless a torque ripple control strategy is employed. This paper presents a modified torque control method for SRMs to reduce their torque ripple. The method is based on a combination of instantaneous direct torque control method and torque-shared functions method; maintaining constant torque during the transition from one phase to another, by turning off transistors of the outgoing phase and determining the required current of the incoming phase, thus eliminating the number of switching of the transistors.
Simulation results show that the proposed method successfully eliminates the motor torque ripple, especially when the motor runs at the average to the nominal speed, the proposed method is more effective (from the energy point of view) than the method of torque shared functions with a cosinusoidal relationship.
The advantages of the modified control method are the simplicity of the control algorithm compared to the direct torque control method, since the adjustment of the ripple level requires one firing angle definition (the value of which varies with the motor speed), and less number of regions in which the structure of the relay regulators changes, which is much simpler than in the direct control as well.
The drawbacks of the proposed modified method include small current pulsations in low-speed zones, and increased demands on microprocessor resources caused by the need to process two three-dimensional tables.