Adaptive full-order observer with high-frequency signal injection for synchronous reluctance motor drives

A back-EMF-based position observer for motion-sensorless synchronous reluctance motor drives is augmented with high-frequency signal-injection method for improved low-speed operation. Previously proposed observer structure is further improved to account for the cross saturation in the motor. The combined observer is experimentally evaluated using a 6.7kW synchronous reluctance motor drive in low-speed operation and under various load conditions. The resulting position error at low speeds and standstill is small.