混合三电平DAB变换器软开关分析与多目标优化调制技术研究

Investigation on Soft Switching Characteristics and the Multi-objective Optimized Modulation Strategy for Hybrid Three-level DAB Converter

该文以混合型二极管箝位型三电平双有源桥(neutral point clamped hybrid three-level dual active bridge,HN3L-DAB)变换器为研究对象。相比于两电平DAB变换器,HN3L-DAB的三电平结构引入中间电平,增加了控制自由度,从而更灵活地控制电感电流。文中首先分析NH3L-DAB的工作原理,推导出各器件动作时的电感电流值以及各工作模式的功率传输函数。在此基础上,针对一类输入高电压、输出大电流场合的应用需求,结合NH3L-DAB变换器的软开关特性,提出了高效率多目标优化调制策略,旨在同时减小导通损耗和开关损耗,兼顾实现高电压侧零电压开通、大电流侧零电流关断、降低电感电流有效值。最后搭建实验平台进行实验,在不同工况下验证三电平DAB变换器拓扑方案的可行性和多目标优化调制策略的有效性。

This paper is focused on the Neutral Point Clamped Hybrid Three-level dual active bridge(HN3L-DAB) converter. Comparing with the two-level DAB converter, NH3L-DAB converter takes advantages of three level architecture, thereby adding an extra control degree. Hence, it can shape the inductor current with better flexibility. Firstly, the operation principle of NH3L-DAB converter was investigated. The inductor current value for each switching moment and the power transmission function for each operating mode were calculated in detail. On this basis, with combining the soft switching characteristics of NH3L-DAB converter, this paper introduced a multi-objective optimized modulation strategy for the applications with high input voltage and large output current. The proposed modulation method can achieve zero voltage switching in high voltage side, zero current switching in large current side, and low RMS value of inductor current, therefore, it can reduce both conduction losses and switching losses simultaneously. Finally, a prototype of DAB was built, and the experimental results demonstrated the feasibility of three level DAB converter topology and the effectiveness of the proposed multi-objective optimized modulation scheme.