Protection and Control Implementation for Bidirectional Step-Up/Down Partial Power Converter for Droop-Controlled DC Microgrids

Partial power converters enable the implementation of highly efficient DC-DC energy conversion systems. Step-up/down partial power converters show the highest potential for improving power density, efficiency, and implementation cost. Recent literature clearly shows that the most flexible implementations of these converters are based on galvanically isolated current-fed dc-dc converter topologies. On the other hand, these topologies are prone to overvoltage on semiconductors and can have poor current controllability at zero voltage in the series port. In practice, these partial power converters must implement multimode control, soft start, and protection of partial-voltage-rated semiconductors. This paper demonstrates these issues in a partial power converter and proposes implementation techniques to resolve them. The experimental verification demonstrates the effectiveness of the proposed techniques, suggesting that the partial power converters could be brought to industrial use.