Improved Nonisolated High-Gain Transformerless DC–DC Converter for Electric Vehicle Applications

To ensure the desired higher voltage conversion ratio (VCR) from fuel cell stacks, nonisolated high-gain dc–dc converters play a crucial role in electric vehicles (EVs). High-gain converters are essential because EVs often require a wide range of higher voltage levels to meet the demand for the dc bus, which drives the traction motor and other modules in a vehicle. To mitigate the use of extreme duty ratios in conventional high-gain converters, a triple-switch, switched-inductor, switched-capacitor (SC) dc–dc converter is proposed. This converter integrates an additional auxiliary switch, a simple resonant cell, and a voltage multiplier cell (VMC). These integrations provide the desired VCR while all switches operate at a nominal duty ratio, ensuring improved efficiency and minimizing switching losses by maintaining soft-switching ability. Furthermore, the proposed converter facilitates zero current switching (ZCS) turn-on operation for all switches through the utilization of an auxiliary inductor, an auxiliary capacitor, and two diodes. The operation of the proposed converter is analyzed in continuous current mode, steady-state gain, and efficiency analysis are discussed in detail. The proposed converter is compared with the existing converters and a 200 W laboratory prototype is developed to validate the theoretical analysis or to prove the effectiveness of the converter.