Multiphase Low Stresses High Step-Up DC–DC Converter With Self-Balancing Capacitor Voltages and Self-Averaging Inductor Currents

Voltage gain ratio is a key limitation faced by nonisolated dc–dc converters in practical applications. Low voltage and current stresses, small volume, simple sampling control circuit, low cost, suitability for high power, scalability, and modularization are optimization trends of the dc–dc converter design. To improve the above-mentioned performance, a multiphase high step-up dc–dc converter is proposed, with advantages of high voltage gain, low switching voltage stresses, low switching current stresses, low capacitor voltage stresses, low output voltage ripple, capacitor voltages self-balancing feature, inductor currents self-averaging feature, ease of extension, and being able to be modularized. The topology derivation, comparisons with other high step-up converters, the operating principle, characteristics, and mathematical models of the proposed converter are studied in detail. Finally, a laboratory prototype of the proposed dc–dc converter operating from 400 to 800 W is built and implemented with input being 24 V and output being 400 V. The experimental results verify the feasibility and superiority of the proposed converter. The proposed multiphase high step-up converter is suitable for the applications, such as fuel cells, electric vehicles, energy storage systems, photovoltaic systems, and microgrids.