A Novel Single-Phase Three-Wire Three-Level Power Inverter with a Balance Bridge

This article presents a single-phase three-wire three-level power inverter with a balance bridge. The topology of the proposed converter is based on two NPC legs and a 2L leg. SPWM modulation technology and a PI-based controller are applied to regulate the voltage. The two phases are controlled independently. To regulate the phase voltage, a voltage outer loop and a current inner loop are applied to each phase. A dc-link voltage balance technology is proposed based on the model of the converter. The converter can work on-grid and off-grid by switching the control loop. Experimental results are presented to verify the effectiveness of the proposed topology and control strategy.