Novel soft switched interleaved DC-DC converters for integration of renewable sources and storage into low voltage DC micro grid

Abstract

DC micro grids are being researched as future energy solutions for integrating distributed renewable sources with storage for localized power management. For integration with low voltage (48 V) DC micro grid, the DC converters are required to operate with high current densities (>10 A) requiring them to have interleaved structure and soft switching for minimizing losses, reducing size and improving efficiency. Novel interleaved soft switched non-isolated buck-boost converters for integration of renewable sources and energy storage systems like solar photovoltaic, battery, ultra-capacitors and fuel cells with DC micro grid are proposed. The two phase interleaved converters utilize zero current switching (ZCS) auxiliary circuits which achieve soft switching for the main switches using only a single auxiliary switch, which also operates under soft switching. Major advantages of the proposed configurations are modularity, simple control strategy based on duty cycle modulation and reduction of device stresses compared to other soft switching topologies. The converter topologies with soft switching cells have been designed for low voltage, high current configurations and experimental results are presented for a 250 W interleaved boost converter.