Peak Current Reduction of Bidirectional-Asymmetrical-Power-Flow DC-DC Converters for Low-Penetration-Renewable-Energy Power Distribution Networks

The bidirectional-asymmetrical-power-flow (BAPF) dc-dc converters, which consist of the uncontrolled rectification power path dealing with large forward power and the active power path dealing with small reverse power, show the potential for constructing simple and reliable ac-dc or dc-dc power electronics transformers (PETs). However, the peak current caused by the uncontrolled rectification power path threatens the security of the active switches in the medium-voltage (MV) side and increases the power loss. This article analyzes the active operation mode of the BAPF dc-dc converter and proposes the optimized operation method for the peak current reduction. Based on those, a downscaled experimental prototype is developed, and the correctness of the theoretical analysis and the optimization method are verified by experimental results.