To improve the efficiency and power density of electronic vehicles, battery packs with higher voltage levels have been gradually adopted. This change poses new challenges for conventional battery charger designs based on two-level topologies and low-voltage rating switches. Therefore, in this article, a bidirectional buck–boost three-level series-resonant converter (BBTL-SRC) for high-output voltage applications is proposed. The voltage stress of switches is reduced to only half of the output voltage, so the low-voltage rating switches with lower losses and costs can be used. In addition, the phase shift and pulsewidth modulation strategies are designed to realize buck and boost conversion. All switches can achieve zero-voltage switching, and the reactive current in resonant tank decreases significantly. Hence, the switching and conduction losses are reduced and efficiency is optimized. The operation principles and characteristics are analyzed in detail, and design considerations are provided. A 3.3-kW, 600–840-V output prototype is built and tested. The experimental results verify the effectiveness of the proposed BBTL-SRC.

中文翻译：

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具有降压-升压能力的高效双向三电平串联谐振转换器，适用于高输出电压应用

为了提高电动汽车的效率和功率密度，更高电压等级的电池组逐渐被采用。这种变化对基于两电平拓扑和低额定电压开关的传统电池充电器设计提出了新的挑战。因此，在本文中，提出了一种用于高输出电压应用的双向降压-升压三电平串联谐振转换器 (BBTL-SRC)。开关的电压应力降低到输出电压的一半，因此可以使用损耗和成本较低的低额定电压开关。此外，相移和脉宽调制策略旨在实现降压和升压转换。所有开关均可实现零电压切换，谐振槽内的无功电流显着降低。因此，开关损耗和传导损耗降低，效率得到优化。详细分析了工作原理和特点，并提供了设计考虑。构建并测试了 3.3 kW、600–840 V 输出原型。实验结果验证了所提出的 BBTL-SRC 的有效性。