The True Unit Power Factor Converter with Flexible Arrangement for Battery Energy Systems: Series and Separate DC bus connection

Bidirectional power converters are necessary for utility interface of Battery Energy Storage Systems (BESS), which are increasingly being used as a mechanism of improving energy balance between demand and generation over time in the electrical system with an ever increasing penetration of renewable energy sources, like solar and wind systems. Since harmonics are an important issue in the use of high power converters, the True Unity Power Factor (TUPF) converter is an interesting option to provide sinusoidal currents with high efficiency. Previous works presented the TUPF converter with its DC links parallel-connected, which reduces the arrangement options for BESS connections. This work proposes modifications to the TUPF control, specifically the current measurement and conditioning, to allow application with series or individually connected DC links. It also analyses the impact of this modifications, along with unbalanced power conditions, in the power quality. Simulation and Hardware-in-the-Loop (HIL) results are presented to validate the proposal.