A Digital PWM Current Controller for Switched Reluctance Motor Drives

Current control is essential in SRM drives. Conventionally, hysteresis current regulation is utilized for current control in SRM drives, but it has some drawbacks including high sampling rate requirement, sensitivity to switching EMI noise, and varying switching frequency. In this paper, a digital dead-beat PWM current controller for SRM drives is proposed. An observer is introduced to guarantee both fast response and stability of the dead-beat current controller. An improved current sampling method is designed to have a more accurate current sampling and to avoid PWM delay in control loop. Simulation and experimental results show that the proposed observer increases the dynamic response and improves the performance of the current controller. The improved current sampling method avoids oscillations in the control loop. The proposed digital PWM current controller has almost the same performance as hysteresis current regulation and at the same time, avoids its drawbacks.