Triple-Compound-Full-Bridge-Based Multi-Input Converter With Wide Zero-Voltage Switching Range and Wide Conversion Gain

In this article, a triple-compound-full-bridge-based multi-input converter (TCF-MIC) is proposed for the bidirectional operations of power flow, which features wide voltage conversion gain, wide zero-voltage switching (ZVS) range and a reduced number of components and transformer windings. The proposed TCF-MIC can serve as the interface of different dc sources with a load and can provide the load with the energy simultaneously or individually. The primary circuit of the proposed converter is an integration of three full-bridges comprising six switches to generate a five-level voltage. The conversion gain of TCF-MIC can achieve up to four times for the wide variation of source voltage. Based on the voltage matching principle, voltage-second values between two sides of the transformer are set equally for the optimized operation, which is utilized to realize soft switching of the six main power switches within the full load range. Meanwhile, the other two switching elements can also operate in a wide region of ZVS. The operation principle, steady-state analysis, loss analysis, and control design are presented in detail. Finally, a 1-kW experimental prototype is constructed to verify the feasibility of the TCF-MIC, and the correctness of the theoretical analyses is validated by experimental results.