Sensorless control of the switched reluctance motor drive based on the stiff system control concept and signature detection

A new method for sensorless control of the switched reluctance motor (SRM) drive is presented in this paper. This new sensorless control method is based on the stiff system control concept and signature detection technique. Suppose, initially, the SRM is controlled without any position sensor and running at synchronous operation with each phase current pulse resting on the positive phase inductance slope. A load disturbance will cause the rotor speed to change and each phase current pulse to shift along with the phase inductance profile. The rotor speed will change much slower than the phase currents because the mechanical time constant is much larger than the electrical time constant. If there exists a signature in the phase current, indicating the shifting of the phase current pulse, the controller can detect the shifting of the phase current pulses by monitoring this current signature and correct the phase excitation to bring the current pulses back to the positive inductance slopes before the rotor speed changes too much. This can be done because the control time constant is much smaller than the electrical time constant. Simulation and experimental results are presented to show the validity of this sensorless SRM control method.