基于组合型双向DC-DC变换器的超级电容储能系统控制策略分析与设计

Analysis and Design of Control Strategy for Combined-BDC Based Ultra-capacitors Energy Storage Systems

研究了一种基于组合型双向DC-DC变换器BDC(bidirectional DC-DC converter)的超级电容储能系统,该系统采用多组多通道交错Buck/Boost双向变换器串联,既可实现开关电流和电压应力的降低也可实现电感量的减小,同时有助于减轻超级电容单体电压低与应用场合电压高间的矛盾。串联变换器模块间的均压控制是该系统稳定运行的关键之一。基于双向变换器的小信号模型分析了超级电容储能系统电流控制与变换器模块均压控制的关系,设计了组合型双向DC-DC变换器的双闭环控制策略,在稳定控制超级电容充/放电电流的同时实现模块输入电压均衡的解耦控制。进一步根据母线电压变化及超级电容荷电水平提出了储能系统能量控制策略。通过两组三相交错Buck/Boost级联BDC储能系统的实验验证了控制策略的有效性。

A novel energy storage system（ESS） with ultra-capacitors（UCs） which is based on the combined bidirectional DC/DC converter（BDC） was studied. The system utilizes the series connection of several multi-channel interleaving Buck/Boost bidirectional DC/DC converters. This structure enables reduction of the inductance and the stress of the switching currents and voltages, and the inconsonance between low monomer voltage rating of the UCs and requirements in the high voltage applications can be mitigated in this system. Since the voltage equalization of input sides is critical for stable operation of the system, the inherent relationships between the system current control and the input sides voltage sharing were analyzed based on the small signal model. Based on the analysis, a double closed-loop control strategy for the combined BDC based ESS, which decouples the inductance current control and the BDC voltage sharing control, was presented. Furthermore, the energy management strategy based on the DC bus voltage and the state-ofcharge（SOC） of the UCs was proposed. The effectiveness of the proposed control strategies for the combined BDC based UCs ESS is validated by the experimental results.