Position-controlled synchronous reluctance motor without rotational transducer

This paper presents a position sensorless control scheme of a synchronous reluctance motor (SynRM) combining a high-frequency current injection method in the low-speed region and the flux estimation method based on the stator voltages in the high-speed region. The rotor has inherent saliency, and its angle can be estimated from d-axis stator current injection and the appropriate signal demodulation in a low-speed region. In the high-speed region, the rotor angle can be estimated by the stator flux from the voltage information. This scheme gives a robust and dynamic estimation of the rotor angle independent of the operating conditions, including speed and load conditions. Experimental results of closed-loop speed and position control with a 3.75-kW axially laminated SynRM are given to verify the proposed scheme.