Low speed and standstill operation of sensorless direct torque and flux controlled IPM synchronous motor fed by matrix converter

This paper proposes a sensorless direct torque and flux control system using indirect space vector modulation for matrix converter driven IPM synchronous machine, operating over a wide speed range including standstill. A novel stator flux observer is enhanced by introducing a correction term in the adaptive model, derived from the d-axis current estimation error at high and medium speeds and from the error signal of high-frequency signal injection at low speeds. The closed-loop control of torque and stator flux is achieved by a variable-structure torque and flux controller and indirect space vector modulation (ISVM) technique. The effect of the input filter capacitor on the input current is compensated by introducing a correcting angle in the ISVM. The effectiveness of the proposed sensorless DTFC-ISVM matrix converter drives is verified by experiments.