Digital PLL technique for precise speed control of SR drive

Abstract

The switched reluctance drive is known to provide good adjustable speed characteristics. However, higher torque ripple and lack of the precise speed control are drawbacks. These problems lie in the fact that SR drive is not operated with an MMF current specified for dwell angle and input voltage. To reduce torque ripple and to have precise speed control, the SR drive has to control the dwell angle and input voltage instantaneously. In the paper, a PLL (phase locked loop) technique is adopted to regulate the dwell angle and input voltage. A PLL control technique in conjunction with a dynamic dwell angle control scheme has good speed regulation characteristics. The DSP based control system is used to realize this drive system. Test results show that the system has the ability to achieve good dynamic and precise speed control.