A DC voltage control method of cascaded H-bridge inverter for power quality conditioner

In recent years, multilevel technology has become an effective and practical solution for moderate and high voltage application field. In all multilevel technology, cascade multilevel inverters have become the major circuits used in power quality conditioners. Evidently,the voltage balancing problem of DC capacitors of cascade inverters is a key problem to the power quality conditioners. This paper explores voltage balancing control fundament. A model for charge and discharge processes of DC capacitor is established based on the point of output pulses of H-bridge inverters. Furthermore, based on the above discussing, a novel algorithm is proposed to balance the dc capacitor voltages. The simulation and experiment results illustrate that the voltage of each capacitor is controlled and balanced while working.