A new voltage-balancing method for split-capacitor inverters using split-output front-end rectifiers in AC-DC-AC applications

In this paper, a new method to balance the DC bus capacitor voltages of two-stage AC-DC-AC converters with split-capacitor inverters is proposed. Converters use such split-capacitor inverters for various reasons such as cost, improved harmonic content and lower switch voltage stresses than those of conventional two-level, six-switch inverters, but the effectiveness of such inverters is limited by the need to perform voltage balancing. The proposed method frees the inverter from having to do such voltage balancing by using a novel approach that involves the front-end AC-DC converter. The paper introduces the new method, explains its basic operating principles and show how certain potential drawbacks are avoided. The feasibility of the proposed voltage balancing method is confirmed with results obtained from an experimental prototype.