High Step-Up Bidirectional DC-DC Converter with Interleaved Resonant Soft-Switching

To address the voltage conversion requirements of photovoltaic power generation systems, this paper proposes an interleaved resonant soft-switching bidirectional DC-DC converter with parallel connection. The converter features two energy transfer modes. Specifically, the forward energy transfer mode (FETM) achieves an eight-fold step-up effect when the transformer turns ratio is 1. The reverse energy transfer mode (RETM) is further subdivided into two sub-modes: RETM1 and RETM2. RETM1 exhibits high step-down capability but requires more power MOSFETs. RETM2 further suppresses switching losses by altering the position of the input voltage, making it suitable for applications with lower step-down gain. Initially, this paper elucidates the operational principles of the different working modes, encompassing the operational stages and the realization process of soft-switching. Subsequently, the characteristics of voltage conversion ratio and current ripple under various working modes are analyzed with an extended analysis of the topology. Based on this foundation, a comparative analysis of the proposed converter with existing schemes is performed in terms of indicators such as voltage gain and current ripple. Then, the parameters and specifications of each component are determined, and a 400 W prototype is designed. Experimental validation successfully demonstrates the effectiveness and reliability of the proposed converter design. The results indicate that the converter operates with efficiencies of 95.4%, 95%, and 93% in FETM, RETM1, and RETM2, respectively.