Integration of non-isolated DC–DC converters in battery storage systems – a topological exploration

This paper presents a topological exploration and evaluation of modularised battery systems with integrated non-isolated DC–DC converters (battery-integrated-converters). Converter requirements for battery operation in charging/discharging, charge balance, bypass, and pass-through modes have been considered. Topological variations have been derived to permit all battery operation modes. Design considerations and equations for each topology have been presented. The topological requirements have been summarised in tabular form with a 380 V bus storage system case study presented to demonstrate application of the design consideration discusses to a typical battery system specification. The comparison shows the buck, boost, and non-inverting buck-boost-based converters are all similarly suitable, and other performance metrics are likely to determine the best choice for a given set of circumstances.