An Integrated Interleaved Ultrahigh Step-Up DC-DC Converter Using Dual Cross-Coupled Inductors With Built-In Input Current Balancing for Electric Vehicles

An integrated interleaved dc-dc converter with ultrahigh voltage gain and reduced voltage stress based on the coupled-inductors and switched-capacitor circuits is proposed in this article, which is suitable for interfacing the low-voltage energy sources, such as fuel-cell, with a high-voltage dc bus in electric vehicle applications. Input-parallel connection of the coupled-inductors offers a reduced input current ripple and the current rating of components, as well as automatic input current sharing without a dedicated current sharing controller. A promising power-density improvement technique is given, in which only one magnetic core is utilized to implement two coupled-inductors that can provide the filter functionality, as well as transformer behavior. For suppressing the voltage ringing resulting from the leakage inductors, the active-clamp configuration is employed that can facilitate the soft-switching performance for all switches in a wide range of output power. A voltage multiplier stage is adapted to not only boost the voltage gain but help alleviate the reverse-recovery problem of diodes. The steady-state performance, theoretical analysis, and a comparison with the state-of-the-art converters are given in this article. Finally, the experimental results of a 1-kW, 100-kHz prototype are provided to confirm the validity of the proposed concept.