Complementary Vector PWM Phase Current Reconstruction Strategy for T-type Three-Level Inverter

Aiming at the problem of unobservable areas (UAs) of neutral current in the traditional space vector pulse width modulation method for T-type three-level inverters (THLIs), the sampling mechanism of neutral current and the existence mechanism of UAs are analyzed. A complementary vector pulse width modulation (CVPWM) strategy for phase current reconstruction with THLIs is proposed. Based on the principle of volt-second balance and synthetic zero vector, different compensation vectors are inserted in the UAs, and the original switching sequence is rearranged, so as to compensate for the dwell time of the observable voltage vectors and eliminate the UAs of neutral current. Experimental results confirm that the proposed method achieves accurate and stable neutral current detection and enables complete three-phase current reconstruction in THLIs.