Input-series and output-series connected modular full-bridge PWM DC-DC converter with capacitive output filter and common duty cycle

This paper proposes a modular isolated dc-dc converter, based on the input-series and output-series (ISOS) association of the full-bridge PWM (FB-PWM) dc-dc converter with capacitive filter. The main attribute of the proposed architecture is its ability to provide self-balance of the input and output voltage across the individual converters, without voltage loop control scheme, both in the steady state and transient operations. Circuit operation, theoretical analysis and modeling are included in the paper, along with experimental results taken from a laboratory prototype with four modules, 1600 Vdc total input voltage, 1600 Vdc total output voltage, 4 kW output power, and 40 kHz switching frequency. Possible applications include high voltage power supplies, solid state transformers, dc current distribution systems, and renewable electric energy systems.