A Novel DCM Soft-Switched SEPIC-Based High-Frequency Converter With High Step-Up Capacity

A novel discontinuous conduction mode (DCM) soft-switched single ended primary inductor converter (SEPIC)-based high-frequency converter is presented in this article with the advantages of high voltage gain and low voltage stress. In order to achieve higher voltage gain, it integrates a switched inductor with a coupled inductor-based modified SEPIC converter, and a resonant cell is built with integration of a resonant capacitor, which enables the switches to work under zero voltage switching (ZVS). Therefore, the working principle is changed and better performance is obtained. The proposed converter can operate in both continuous conduction mode (CCM) and DCM, but ZVS can only be achieved in the discontinuous mode; hence, DCM is more suitable for high-frequency applications. Mode analysis, parameter design, and boundary of the two working modes are all presented in detail. For higher efficiency, a 500-kHz/54-W DCM prototype with 15 voltage gain has been designed to demonstrate theoretical analysis. Obtained efficiency was up to 93.4% at full load. Experimental results show good accordance with theoretical analysis.