Expandable High Step-Up Soft-Switching Integrated Boost–SEPIC Converter With Y-Source Coupled Inductor

This article proposes a high step-up soft-switching integrated boost–SEPIC converter with a Y-source coupled inductor for interface circuits of renewable energy power generation systems. By combining the boost converter, the SEPIC converter, and the Y-source coupled inductor, the converter achieves a higher voltage gain. In addition, it features a low input current ripple and a common ground for both the input and output. A series of multiple switched capacitor units can be cascaded on the output side of the converter, allowing for enhanced flexibility and expandability. The output voltage is shared by three capacitors, which effectively reduces the voltage stress on the capacitors and reduces the size of the capacitors. In addition, the active clamping circuit effectively utilizes the leakage inductance energy, enabling zero-voltage switching (ZVS) for the switch and zero-current switching (ZCS) for the diode, thereby reducing the loss of the switching elements. Since the switch is positioned before the Y-source, the switch also has lower voltage stress and operates over the full duty cycle range. This article presents a detailed analysis of the operating principle and steady-state performance of the converter. A 400-W experimental prototype was constructed to validate the correctness and feasibility of the theoretical analysis.