Theory analysis of the hypostasis of DC voltage balancing control for power quality conditioners with cascaded H-bridge inverter

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 mainly focuses on exploring the hypostasis of various voltage balancing control methods. A comprehensive theoretical analysis of voltage balancing control fundament is presented. The issue of voltage balance is discussed from output pulses of H-bridge inverters point of view, and a model for analyzing the charge and discharge process of H-bridge DC capacitor is established. Furthermore, all regulation means of output pulses of H-bridge inverters for redistributing active power is reported and quantified.