A high efficiency DC/AC inverter for energy balancing of battery modules

Battery energy balancing is crucial in large scale battery energy storage applications. By power electronic circuits, energy transfers from one battery to another with little loss. This paper introduces a DC/AC inverter for battery modules balancing. The DC port is connected to positive and negative electrodes of a battery module and the AC port is connected to that of another inverter. Therefore, more than two inverters can be joined together to the AC bus for battery balancing at the same time. Among all of the inverters, one is a master and the others are slaves, for that is convenient to keep all the inverters work at the same frequency and phase. Energy transfers from the batteries with high voltages to those with low voltages. The currents are auto-adjusted according to the voltage differences. The experiment results showed that the balance current is up to 10A and the power efficiency of the DC/AC inverter achieved higher than 96%.