High step-up converter with passive lossless clamp circuit and switched-capacitor: Analysis, design, and experimentation

In the paper, a novel high step-up dc-dc converter with coupled-inductor and switched-capacitor is proposed for sustainable energy system. The converter utilizes two-stage switched-capacitors as voltage sources to extend the voltage gain and auto-balance two branches current. Besides, the voltage stress on the main switches is reduced further due to the voltage distributed on the switched-capacitors. The Winding-coupled inductors work in fly-back or forward mode at different operation stages, which extends the voltage gain and make use of the magnetic as possible to improve the power density. The main switches are turned off under zero voltage switching(ZVS) condition because of a passive clamp circuit and turned on under zero current switching (ZCS) condition due to the coupled inductor inherent leakage. Additionally, the diode reverse-recovery problem is alleviated because its current falling rate is controlled by the leakage inductance. Thus, the efficiency can be further improved. Then, the operating principle and performance of the converter are discussed in detail. Finally, a prototype circuit with 20-V input voltage, 200-V output voltage and 300-W output power is implemented to verify the performance of the proposed converter.