This paper proposes a single-switch integrated Sepic converter with a Y-source coupled inductor. The three-winding coupled inductor has higher voltage regulation efficiency, and the three-port tap of the y-source is easier to integrate with other structures to form a composite power cell. While ensuring the continuous input current, it can flexibly adjust the voltage gain, increase the power capacity, and reduce the voltage stress of the switch. The diode-capacitor branch in the integrated topology is used as a clamp to suppress the voltage shock while using the absorbed leakage energy to achieve soft-switching characteristics, mitigate diode reverse recovery, and improve the efficiency of the converter. The converter can be applied to the output of the photovoltaic (PV) array, a detailed theoretical analysis of the converter is carried out, and the general extension of the topology and the extension of the converter family are given. Finally, a 150 W prototype was built to verify that the converter can achieve high gain under high efficiency.