基于双向零电流开关的分布式储能变换器研究

Research on Distributed Energy Storage Converter Based on Bidirectional Zero Current Switching

为提高电池利用率及安全性,分布式储能系统采用高频隔离储能变换器实现低压电池模组到高压直流母线的能量双向传输。为使储能变换器在正反两个方向下均具有较高效率,低压大电流一侧在双向运行时可采用零电流开通和零电流关断,以实现零开关损耗。在分析传统双向全桥DC/DC变换器和LLC谐振变换器存在问题的基础上,提出了一种双向零电流开关储能变换器,通过采用非对称占空比控制,可以实现低压侧在正反向时均具有零电流开关特性,有效减小开关损耗,提高变换器的双向运行效率。分析了变换器的功率传输及电压增益特性,推导了软开关实现条件,并对拓扑结构进行改进以改善电流波形,进一步减小损耗。最后通过仿真和实验验证了拓扑结构及双向零电流开关控制方式的有效性。

In order to improve battery utilization and safety,the distributed energy storage system transmits energy bidirectionally between low-voltage battery modules and the high-voltage DC bus through high-frequency isolation energy storage converters.To improve the energy storage converter’ s efficiency in both directions,the low-voltage and highcurrent side can operate in zero-current turning-on and zero-current turning-off during bidirectional to achieve zeroswitching loss.Based on the analysis of the existing problems in traditional bidirectional full-bridge DC/DC converter and LLC resonant converter,a bidirectional zero-current switching energy storage converter is proposed,which can realizes zero-current switching characteristic on the low-voltage side in bidirectional operations through asymmetric duty ratio control method,effectively reducing the switching losses and improving the bidirectional efficiency of the converter.The power transmission and voltage gain characteristics of the converter are analyzed,the soft switching realization conditions are derived,and the topology structure is modified to improve the current waveform and further reduce the losses.Finally,simulations and experiments verify the effectiveness of the topology and the bidirectional zerocurrent switching control method.