Elimination of position sensors in switched reluctance motor drives: State of the art and future trends

This paper covers the range of topics related to sensorless control of switched reluctance motor (SRM) drives from their fundamentals to their limitations and state of the art and future trends. This should help the reader to develop a systematic understanding of the sensorless techniques that have been developed over the past two decades. The inherent vulnerability to mechanical failures, extra cost, and size associated with external position sensors such as optical encoders, resolvers, and custom-designed Hall-effect sensors has motivated many researchers to develop sensorless control techniques for SRM drives. Ideally, it is desirable to have a sensorless scheme, which uses only terminal measurements and does not require additional hardware or memory while maintaining a reliable operation over the entire speed and torque range with high resolution and accuracy. Recent advances in the development of low-cost digital-signal-processor-based microcontrollers have paved the way for the fulfillment of this objective. It is, furthermore, our view that the existing trends in the development of more powerful processors will ultimately replace the concept of sensorless controls with the concept of eliminating the need for position sensing, a concept that will further revolutionize the motor drive technology.