基于移相变频控制的全桥型LLC谐振DC-DC变换器

Full Bridge LLC Resonant DC-DC Converter Based on Phase Shift Frequency Modulation Collaborative Control

采用LLC谐振拓扑的DC-DC变换器在通信电源、锂电池充电器、PC电源等领域广泛使用。对于基本的LLC谐振拓扑,一般采用常规脉冲频率调制(Pulse Frequency Modulation,PFM)的控制方式,这种方式可以在一定范围内实现原边开关管ZVS,副边二极管ZCS,从而显著降低开关损耗,提升电源效率。但单纯采用变频控制无法适应输入输出电压宽范围变化的要求,因此提出了一种基于移相-变频协同控制的全桥型LLC谐振DC-DC变换器,介绍了变换器硬件组成和控制算法,并在一台工程实验样机上进行了验证。

DC-DC converter with LLC resonant topology is widely used in communication power supply,lithium battery charger,PC power supply and other fields.For the basic LLC resonant topology,Pulse Frequency Modulation(PFM)control mode is generally adopted.This mode can realize the primary side switch ZVS and secondary side diode ZCS within a certain range,so as to significantly reduce the switching loss and improve the power efficiency.However,only using frequency modulation control can not meet the requirements of a wide range of input and output voltage.Therefore,a full bridge LLC resonant DC-DC converter based on phase shift frequency modulation cooperative control is proposed in this paper.The hardware composition and control algorithm of the converter are introduced and verified on an engineering experimental prototype.