A novel improved high-gain quadratic DC-DC converter based on two synchronous power switches and a two-winding coupled inductor.

This paper presents a novel quadratic high-gain DC–DC converter employing two synchronously operated power switches and a two-winding coupled inductor for efficient low-voltage to high-voltage power conversion. The proposed topology achieves a large step-up voltage gain through the combined action of a quadratic boosting structure and magnetic coupling, while maintaining operation at moderate duty cycles. The voltage conversion ratio can be flexibly adjusted by both the duty cycle of the active switches and the turns ratio of the coupled inductor, providing an additional degree of freedom in converter design. The converter operates with a continuous input current, reduced voltage stress across semiconductor devices, and common-ground configuration between input and output, making it suitable for renewable-energy applications such as photovoltaic and fuel-cell systems. In addition, soft-switching operation is achieved for diode D3, which contributes to lower switching losses and reduced electromagnetic interference. The operating principles of the converter in continuous conduction mode are comprehensively analyzed, and the steady-state characteristics are derived. A detailed comparison with existing high-gain topologies demonstrates the advantages of the proposed structure in terms of voltage gain, component count, and device stress. Finally, experimental results obtained from a 300 W laboratory prototype operating at 50 kHz verify the theoretical analysis and confirm the capability of the converter to boost a 25 V input voltage to a regulated 400 V output with high efficiency.