A high voltage gain solid-state transformer for integration of renewable energy and AC sources

This paper introduces a novel high-voltage gain topology for a solid-state transformer, integrating a DC-DC converter and dual active bridge converters. The proposed design features three DC links operating at different voltage levels. The first DC link connects to a single-switch high step-up DC-DC converter, while the second DC link interfaces with an AC source via a rectifier, allowing the use of both DC and AC inputs. A high-frequency transformer ensures galvanic isolation between the sources and the third DC link. The DC-DC converter employs coupled inductors and voltage multiplier cells, offering distinct advantages such as a high voltage gain, reduced voltage stress on semiconductors, and minimized current ripple. These features make the topology highly suitable for transferring power from renewable energy sources, such as photovoltaic panels, to a high-voltage DC link in microgrid or nanogrid applications. The novelty lies in the combination of multiple voltage levels, high-frequency isolation, and the ability to handle both DC and AC inputs efficiently. An experimental prototype, delivering 620 W with a 25 V DC input and 110 V AC input, is built, and the results validate the converter's effectiveness.