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.