Existing high step-up DC-DC converters suffer from various issues, including limited voltage gain, high voltage stress on semiconductors, and high current ripple. To solve these issues, a step-up converter with ultrahigh gain (40x at 50% duty cycle for a turn ratio of 2) composed of two boosting stages, a three-winding coupled inductor, a charge pump and a switched capacitor is presented. The other positive structural properties of the proposed converter are the low current ripple of its input source, the low voltage stress on its switches and most of the diodes, and the existence of a common ground between the input and output sides. The circuit configuration of the proposed converter requires a smaller series inductor due to its ability to achieve the same voltage gain as similar converters with a smaller duty cycle. Additionally, the proposed converter exhibits a low input current ripple, further distinguishing it from similar converters. The coupled inductor is placed in a way to effectively decreases voltage stress on the switches. The converter is compared with the other high step-up converters from different viewpoints demonstrating its superiority including power density and cost-effectiveness. An experimental prototype, rated at 240W with 20V input voltage and 400V output voltage, is reported to validate the theoretical analysis, performance quality, and dynamic response of the converter.
