Multi-level inverter and method for providing multi-level output voltage by utilizing the multi-level inverter

Abstract

A multi-level inverter provides multi-level output voltage. The multi-level inverter includes at least one cascaded H-bridge multi-level module. Each H-bridge multi-level module comprises a first H-bridge multi-level leg and a second H-bridge multi-level leg connected in parallel. Each of the first and second H-bridge multi-level legs includes a first inverter leg and a second inverter leg coupled in parallel through a coupled inductor. The first and second inverter legs are coupled respectively to a primary winding and a second winding of the coupled inductor for providing first and second input voltages with multiple voltage levels. The primary and secondary windings of the coupled inductor are coupled in series and a junction node of the primary and secondary windings forms an output terminal of the H-bridge multi-level leg. The first input voltage has a predetermined phase shift relative to the second input voltage. The multi-level inverter can have lower change in output voltage and thus eliminates problems caused by a large change in output voltage.