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.