ABSTRACT In this paper, an isolated integrated boost‐flyback high step‐up converter with active clamp is proposed. Based on the boost‐flyback topology, which combines the advantages of boost and flyback converters, a high step‐up ratio is achieved by employing a coupled inductor. The converter adopts an ideal transformer to provide energy transfer and galvanic isolation. The energy stored in the leakage inductance can be recycled by the active clamp circuit, thereby reducing voltage spikes on the switches and improving conversion efficiency. Additionally, the topology is designed such that the active clamp function is integrated into the two main switches. Furthermore, zero‐voltage‐switching (ZVS) turn‐on is realized for both switches, which reduces switching losses and enhances efficiency. Owing to the high step‐up capability, the proposed topology alleviates the voltage stress on the primary‐side devices, inherently avoids duty cycle operation above 50% to simplify the design, and, due to its integrated structure, requires fewer components. Finally, the proposed converter is implemented with a rated power of 1 kW, an input voltage of 48 V, and an output voltage of 400 V to verify its feasibility. Experimental results demonstrate a maximum efficiency of 97.38% at 300 W and 94.38% at full load of 1 kW.
Tseng et al. (2026) studied this question.