三角形模块化多电平DC/DC变换器研究

Study on triangular modular multilevel DC/DC converter

DC/DC变换器是双母线直流微网中的接口变流器,在能量转换中起重要作用。因传统DC/DC变换器具有器件应力高,电压增益低等缺点,导致其不适用于中高功率场合。模块化多电平DC/DC变换器通过模块串并联方式降低器件应力,提高电压增益,适用于中高功率场合。本文以三角形模块化多电平DC/DC变换器作为研究对象,对电路拓扑结构与工作原理进行分析,该电路所有模块可实现均压均流,电路功率均分至各个模块。针对电路中变量相互耦合的关系,研究设计解耦控制策略,实现两级间的变量解耦;针对非交错调制方式下电压纹波大的特点,提出不同级间交错调制方式,在所提方式下电路拥有良好的动静态性能,并且可以有效降低输出电压纹波。通过MATLAB/Simulink搭建仿真模型,仿真结果验证了解耦控制策略及调制方式的可行性及有效性,提高了电路动态特性及输出直流电能质量。

DC/DC converter,an interface converter of double bus in DC microgrid,is taken as an important role in energy conversion. In view of the shortcomings of traditional DC/DC converters such as high stress and low gain,it is not suitable for medium and high power applications. Low device stress and high voltage gain of modular multilevel DC/DC converters is realized through module series and parallel connections,it is suitable for medium and high power applications. The triangular modular multilevel DC/DC converter was taken as the research object to analyze the circuit topology and working principle in this paper. The equality of voltage and current sharing was realized in all modules of the circuit,and the circuit power was equally distributed to each module. For the coupling relationship of variables in the circuit,the decoupling control strategy was researched and designed. For the characteristics of large voltage ripple under the noninterleaved modulation mode,the interleaved modulation method between different stages was proposed. In the proposed method,good dynamic and static performance was realized,the output voltage ripple was effectively reduced. Finally,a simulation model was built through MATLAB/Simulink,the feasibility and effectiveness of the decoupling control strategy and modulation was verified through the simulation,the dynamic characteristics of the circuit and the output DC power quality was improved.