多电平直流变换器的解耦控制与闭环设计

多电平直流变换器利用飞跨电容使得输入电压在串连的各开关管之间均分,以降低开关管的电压应力。但该变换器是一个多输入多输出,强耦合的非线性系统。本文建立了多电平Buck变换器的小信号模型,并利用文献[7]提出的控制方法将该变换器解耦成多个单输入单输出系统,然后进行控制闭环的设计。论文采用三电平Buck变换器进行了实验验证。实验结果表明,本文所建立的小信号模型是正确的,基于该模型设计的补偿网络可以使变换器具有较快的动态响应。实验结果也表明输出电压闭环和飞跨电容电压闭环是相互解耦的。

DECOUPLING CONTROL AND CLOSED-LOOP DESIGN OF BUCK MULTILEVEL CONVERTER

The Multi-level (ML) converter can reduce the voltage stress of the power switches with the use of the flying capacitors. However, the ML converter is a multi-input multi-output, strongly coupled system. This paper builds the model of the Buck ML converter, and decouples it into several independent single-input single-output systems with the control strategy proposed in [7], based on which the design of the closed-loop for the systems are given. The Buck three-level converter is taken as the example to illustrate the design and verified by the experiment. The experimental results show that the modeling and design is valid and the flying capacitor voltage control is independent with the output voltage control.