Input Voltage Unevenness Analysis in Series-Parallel DC-DC Converter

The authors have proposed the series-parallel dc-dc converter as an elemental technology to develop the power supply system that is highly compatible with renewable energy. However, when the series-parallel dc-dc converter is operated, there is an issue that the input voltage is not shared evenly by each dc-dc converter unit that consists of the series-parallel dc-dc converter. The aim of this paper is to analyze the causes of input voltage unevenness under specific conditions. By analysis of the current path through simulation, it is found that the charge and discharge of the input capacitor of each dc-dc converter unit occur, and it became clear that this leads the unevenness in the sharing of the input voltage.