Efficiency improvements in a Single Active Bridge modular DC-DC converter with snubber capacitance optimisation

Modular DC-DC converters are commonly used to increase the power capacity of a DC-DC converter for high power applications. To obtain the required power, multiple modules are connected in the input-parallel and output-parallel (IPOP) configuration. In addition, phase-shedding are used to increase efficiency of such modular DC-DC converters at light-loads. With Single Active Bridge (SAB) modules, efficiency of the system can be further improved by increasing the snubber capacitance which results in Partial Resonant Single Active Bridge (PR-SAB) modules. As the load range of the PR-SAB load range is reduced, certain loads within the entire load range are therefore not attainable when they are connected in the IPOP configuration. This paper describes how snubber capacitance in each module is optimised such that the entire existing load range is maintained while improving system efficiency. In addition, by utilising unequal module power distribution, the overall IPOP converter efficiency is increased over a wide load range to above 94 %. Peak efficiency is also increased to about 96 %. Finally, experimental results for the IPOP converter are obtained with the optimised snubber capacitances in the SAB modules.