Generalised single-phase N-level voltagesource inverter with coupled inductors

Abstract

A generalised single-phase N-level voltage-source inverter is presented in this study. The number of outputvoltage levels is increased by using split-wound coupled inductors instead of several DC voltage sources and split and/or clamp capacitors of the conventional multilevel converters. As an example, the operation of the nine-level inverter isanalysed and a proper switching strategy is proposed. With this modulation strategy, no DC components exist in theinductor voltages and currents, which is very helpful for minimisation of the inductors. Voltage steps are only onequarterof the DC voltage source, leading to much reduced dv/dt. Moreover, this inverter compared with other inverterswith the same number of voltage levels requires fewer switches and passive components. This study uses simulationand experimental results to illustrate the operation of the proposed inverter.