基于多模式控制的储能用双向Buck-Boost DC/DC变换器

由于各种分布式能源的大量接入,电网需要加入储能单元以平抑潮流的波动。储能系统中,为了在宽输入、输出电压范围的情况下实现高效双向电能转换,探讨一种基于多模式控制的双向Buck-Boost DC/DC变换器。当输入电压显著高于输出电压时,变换器工作在Buck模式,采用谷值电流控制。当输入电压显著低于输出电压时,变换器工作在Boost模式,采用峰值电流控制。当输入电压接近输出电压时,变换器工作在Buck-Boost组合模式,采用移相控制来实现平滑过渡。为了实现高精度的输出和快速的动态响应,控制环路采用二型补偿器。通过Buck模式和Boost模式小部分重叠工作的方式,消除了传统Buck-Boost变换器在模式切换时存在的断续现象。制作的1kW实验样机具有97.5%的峰值效率以及Buck模式与Boost模式平滑切换的特点。

Multi-mode control based bidirectional Buck-Boost DC/DC converter for energy storage

Due to the high level penetration of several types of distributed energy source, storage system needs to be added in modern power system to suppress power flow fluctuation. In order to realize high efficiency bidirectional power conversion under the circumstance of wide input and output voltage range in energy storage system, a bidirectional buck-boost DC/DC converter based on multi-mode control is studied in this paper. When the input voltage exceeds the output voltage above a certain threshold, valley current mode control is employed and the converter operates as buck region. When the output voltage exceeds the input voltage above a certain threshold, peak current mode control is used and the converter operates as boost region. Furthermore, when the intput voltage is similar to the output voltage, phase-shift mode control is adopted to obtain seamless transition and the converter operates in a manner of buck and boost combination. In order to realize high accurary output and fast dynamics, Type II compensator is employed. By the approach of small portion overlaping between Buck region and Boost region, the discontinuity happened at region transition in traditional Buck-Boost converter is eliminated. 97.5% peak efficiency is achieved in the 1 kW hardware prototype and the transition between Buck region and Boost region is smooth.