Parallel switch-based chopper circuit for DC capacitor voltage balancing in diode-clamped multilevel inverter

In recent years, the multilevel inverters have become a practical solution for high-voltage application and power quality issues. In all multilevel topologies with several DC links, the voltage balancing of DC capacitors is known as a key problem. In this study, a novel topology of chopper circuit for DC capacitor voltage balancing in diode-clamped multilevel inverters (DCMLIs) is proposed. Presented topology has less number of switches with respect to other proposed topologies in literatures. Suggested topology is modular and has high reliability. Based on the presented control system for chopper switches, only one switch is turned on at each interval. Therefore the conduction and switching losses of the chopper circuit are reduced. Referring to the simulation results, fast dynamic response of suggested chopper and reduction in voltage stress on switches can be seen clearly. Computer-aided simulations are performed through MATLAB Simulink software. A prototype chopper circuit has been implemented and tested. The experimental results are also presented to verify the performance of the proposed chopper circuit and its control system for DC capacitors voltage balancing in DCMLIs.