Regulated Series Hybrid Converter With DC Transformer (DCX) for Step-Up Power Conversion

The partial power converter, which is composed of isolated topology and dc-dc topology is getting more and more attention due to its efficient power delivery. This article proposes a partial power regulated series hybrid converter (RSHC), which is suitable for power conversion in step-up isolated applications. The proposed RSHC architecture consists of a dc-dc converter aiming to regulate the output voltage and a secondary-side series resonant converter (SSRC) operating as a high-efficiency dc transformer (DCX). The resonant tank of SSRC is derived from the reverse structure of a conventional LLC resonant converter. Different from the two-stage structure, the bulk power from the input to output is directly transmitted by SSRC with DCX function (SSRC-DCX), and part of the total power is delivered by dc-dc converter. Moreover, the voltage stress across the power devices of the dc-dc converter in the proposed RSHC is reduced in comparison with the two-stage structure. Therefore, the proposed RSHC can improve efficiency as well as save costs. The steady-state operation principle of RSHC is analyzed. Finally, a 250 W prototype is built to verify the output regulation mechanism and performance of the proposed RSHC.