Dual-Input H-bridge Based 3-Phase Cascaded Multilevel Converter for Utility Scale Battery Applications

Abstract

In this paper, a modified cascaded H-bridge CHB multilevel converter is introduced for utility-scale battery applications. The conventional H-bridge module, used as a building block in CHB, is replaced with a dual-input H-bridge module. In this, a boost converter is connected to a separate battery-set and integrated to each leg of the H-bridge. Such a configuration not only eliminates one power switch from each boost converter, but it also maintains the converter’s flexibility i.e. each boost converter can operate at its own duty cycle. The relationship between the boost duty cycle and modulation index is derived. The proposed topology is able to maintain uniform charging/discharging operation among all connected battery-sets while supplying/absorbing the desired reference power. The validity of the proposed converter is tested using a Matlab/Simulink model in a grid connected mode under different operating conditions.