Sensorless permanent magnet synchronous drive with DTC based on high frequency injections

A new sensorless control algorithm for surface mounted permanent magnet synchronous machines with direct torque control (DTC) is proposed. The DTC usually operates with a short sampling period, therefore estimation algorithms need to be computationally cheap. Moreover, injection of high-frequency (hf) signals into a given axis can be a challenging task in comparison with a standard vector control with a PWM modulator. In this paper, a modification of the DTC algorithm is proposed to enable hf injections in a separate d-axis in a rotating coordinate system. Demodulation of this signal and sensorless rotor position estimation based on both phase-locked loop and modified extended Kaiman filter are described and evaluated. Verification was performed by both simulations and experiments on a laboratory prototype of a PMSM drive with rated power of 11 kW.