A DCM High-Frequency High-Step-Up SEPIC-Based Converter With Extended ZVS Range

A discontinuous conduction mode (DCM) high-frequency high-step-up single ended primary inductor converter (SEPIC)-based converter with extended zero voltage switching (ZVS) range is presented in this article. With the incorporation of some components on conventional SEPIC, the proposed converter achieves better performances such as high voltage gain, low voltage stress, and ZVS. The additional components form a resonant cell which enables the switches to work in ZVS, and switching loss is reduced accordingly. In order to achieve ZVS, the converter is designed to work in DCM. Due to inclusion of the resonance stage, traditional pulse width modulation (PWM) or pulse frequency modulation (PFM) control method is unable to regulate the output characteristics and maintain ZVS of the power switches at the same time. Therefore, a hybrid control method is proposed in this article to guarantee ZVS within a specific load range. According to this hybrid control method, the ZVS range is extended effectively. GaN switches and planar magnetic components are also used. Working principles and steady-state analysis are presented in detail. A 1-MHz 36-W prototype with 10 voltage gain has been designed to demonstrate theoretical analysis. Efficiency obtained is up to 91.8% at full load. Experimental results show good agreement with theoretical analysis.