Current gradient based sensorless control for switched reluctance drives with torque boosting technique

This paper presents a technique to increase the utilization of the dc-link voltage in order to boost output torque at medium speeds for the current gradient sensorless method. In the original method, the controller operates only in the voltage-controlled mode and applies voltage pulses with a constant duty cycle over the entire conduction period. Therefore, the available reserve of the dc-link voltage is not fully utilized to achieve high output torque. The presented method switches from the voltage-controlled mode to the current-controlled mode after the maximum current point has been detected in order to gain higher torque. The functionality of the presented technique was validated by experimental results.