Performance Comparison of Voltage-Fed and Current-Fed Series Resonant Converters for High Step-Up DC-DC Applications

In dc microgrid applications, dc-dc high step-up converters are essential for interfacing with renewable energy sources, where the input voltage is typically low and variable, requiring a wide voltage step-up range to match the DC bus voltage. Series Resonant Converters (SRCs) have attracted significant interest due to their high efficiency and inherent soft-switching characteristics. This paper presents a comparative study of two well-known SRC implementations – Voltage-Fed (VF) and Current-Fed (CF) converters – focusing on their voltage-boosting performance. Each topology employs a distinct boost modulation strategy to regulate voltage gain. To extend the input voltage range, topology morphing control (TMC) is utilized in both converters, allowing operation as a full-bridge inverter (FBI) on the primary side and as either a full-bridge rectifier (FBR) or half-bridge rectifier (HBR) on the secondary side. When configured as an HBR, the secondary H-bridge works as a voltage doubler, resulting in a stepwise increase in converter gain. To experimentally compare both converters in boost mode, a 350 W prototype was developed with an input voltage range of 6–30 V and a regulated output of 350 V. The prototype was operated separately as VF and CF configurations, and their performance, including voltage gain range and efficiency, was recorded and compared in this paper.