A Zero‐Voltage Switching Three‐Level Nonisolated Bidirectional DC/DC Converter With a Lossless Passive Component Auxiliary Circuit and Design‐Oriented Analysis

ABSTRACT A three‐level bidirectional buck/boost converter (TLBBBC) is suitable for power electronic systems with a high‐voltage DC link for its switches with half voltage. In order to achieve higher efficiency, a novel zero‐voltage switching (ZVS) TLBBBC is proposed in this paper to enable operation with higher switching frequencies. In the proposed ZVS TLBBBC, two identical ZVS cells, each composed of a resonant inductor, two snubber capacitors, and two resonant capacitors, are integrated with the conventional three‐level (TL) topology to enable soft switching in all four switches in both buck and boost modes. Here, one advantage is that soft‐switching conditions are ensured under conventional control methods without using the auxiliary switch or complex control methods. In addition, the soft‐switching region is derived, clearly illustrating the relationship between the duty cycle ratio and the power inductor current that ensures the soft‐switching condition. Hence, the soft‐switching region is beneficial for assisting in ZVS cell design and guiding the converter in running in ZVS. Then, the operation and design considerations of the proposed topology are analyzed in detail. Finally, the experimental results of an 800‐W prototype for both the boost and buck modes are presented to confirm the theoretical analysis.