Design and implementation of a 22 kW full-bridge push-pull series partial power converter for stationary battery energy storage system with battery charger

A wide variety of AC/DC power converter topologies have been developed in order to improve the system efficiency, input power factor and system redundancy for stationary battery energy storage systems. Due to the nature of high-power batteries, there is a big voltage difference between battery terminals from the end of discharge to the high charge value. To prevent unregulated battery voltages from harming the system loads, several techniques are used in the industry. A well-known old technique named as diode dropper is simple but suffers from low efficiency. Using a DC-DC converter is more advantageous, although it increases the cost. In this paper, the use of partial power processing converters which attract interest these days has been proposed as an alternative. The proposed full bridge/push-pull series connected partial power converter has a slight modification compared to the classical one presented in the literature. A system with 22 kW power rating was designed and tested. In order to compare the results, a two-switch buck-boost converter was also designed and tested for the same conditions. The results show that the proposed converter is superior to both the two-switch buck-boost converter and other topologies in terms of efficiency and response speed. Efficiencies of 97%-99% have been attained with the proposed converter.