A new combined adaptive flux observer with HF signal injection for sensorless direct torque and flux control of matrix converter fed IPMSM over a wide speed range

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. The adaptive flux observer is enhanced by introducing correction terms in the adaptive model. The first correction is derived from the error signal of high-frequency signal injection at low speeds and the second is from current estimation error for the stator resistance variation. The torque and stator flux control are achieved using two PI controllers and ISVM with a new overmodulation strategy, which is characterized by low ripples in torque and flux, unity input power factor, sinusoidal input/output currents and bidirectional power-flow capability, while maintaining constant switching frequency and fast dynamics. The saturation effect is mitigated by considering the inductance as a function of current. The effectiveness of the proposed sensorless DTFC-ISVM matrix converter drives is verified by experiments.