Assessment of Sliding Mode Observer in Sensorless Control of Switched Reluctance Motors

Several studies have proved that sensorless control methods can improve the overall robustness and costs of a drive while maintaining the desired performance. However, the general approach of these sensorless strategies involves flux estimation which is significantly affected by the uncertainties associated with the machine's terminal measurement errors and noise. In this paper, a simple robust sensorless control of Switched Reluctance Machine (SRM) is described. The inherent robustness to parameter variations and measurement noise coupled with the high stability and simple computation of a Sliding Mode Observer (SMO) is utilized to eliminate the errors often involved in a flux-linkage based position estimation for the SRM. The proposed method is tested under different operating conditions. Results obtained show that it is reliable and less susceptible to errors and noise commonly found in sensorless control of SRM. The method was also found to handle the model uncertainties associated with the approximated model used for the estimation but with reduced performance at low speed.