Analysis of capacitor dividers for multilevel inverter

Abstract

This paper analyses a possibility for realization of multilevel inverters. After general description of all famous solutions, the focus is paid on diode clamped multilevel inverters (DCMI) and flying capacitor multilevel inverters (FCMI). The comparison of topological structure differences and control strategies is presented. The special focus is paid to balancing of voltages on capacitors. Switching states and their transitions of three-level inverter allow to balance capacitor voltages in both types of inverters, DCMI and FCMI, where DCMI requires less capacitor power size than FCMI to achieve the same capacitor voltage swinging. However in higher-level DCMI (more than 3) capacitor voltage balancing generally is not able. FCMI control strategy is possible for all level. Special control strategy for five-level DCMI capacitor voltage stabilization is briefly described. Advantages and disadvantages of DCMI and FCMI are compared for the same output power.