High-step-up-ratio DC/DC converter based on improved SEPIC circuit

The invention relates to a high-step-up-ratio DC/DC converter based on an improved SEPIC circuit and belongs to the technical field of power electronics to solve the problem that a current high-frequency step-up DC/DC converter causes large switching transistor voltage stress and low system efficiency because the switching transistor operates in a hard switching state. The high-step-up-ratio DC/DCconverter based on the improved SEPIC circuit is additionally provided with a switching transistor S2, a diode Da1, a diode Da2, a capacitor Cs2, a capacitor CQ1, a capacitor CQ2, and a capacitor Caand a transformer on the basis of a traditional SEPIC circuit. Due to the introduction of two parallel resonant capacitors, namely the capacitor CQ1 and the capacitor CQ2, both the switching transistors are turned on at zero voltage, which not only reduces the voltage stress at both ends of each switching transistor, but also reduces the loss of the switching transistors and improves system efficiency. The high-step-up-rat