一種適應于直流微電網的全橋LLC變換器

摘" 要： 針對傳統的光伏并網隔離型變換器的變壓器體積大、損耗高和半導體器件電壓應力高等問題，提出一種基于LLC諧振變換器的高增益DC?DC變換器。該變換器滿足了輸入輸出之間電氣隔離的要求，將全橋LLC諧振變換器與開關電容相結合，有效地提高了變換器的增益，減少了變壓器的體積和損耗，降低了半導體器件的電壓應力，實現了開關管的零電壓開通和二極管的零電流關斷，有效地降低了開關損耗。首先對所提變換器的工作原理進行詳細分析；其次用基波分析法分析其基本特性，并進行半導體器件電壓、電流應力計算及電路的參數設計；最后搭建一臺了800 W的實驗樣機，經過實驗驗證，該變換器實現了開關管的ZVS開通，二極管的ZCS關斷；減小了變壓器的體積和銅耗；轉換效率最高可達94.9%。二次側二極管的電壓應力為輸出電壓的[12]，是全橋整流的0.5倍、半橋整流的0.25倍，且平均電流相同，有利于器件的選型，更適用于直流微電網的應用，證明了理論分析的準確性。

關鍵詞： 直流微電網； LLC諧振變換器； DC?DC變換器； 高增益； 電壓應力； 開關電容； 基波分析法

中圖分類號： TN624?34； TM46" " " " " " " " " " "文獻標識碼： A" " " " " " " " " " "文章編號： 1004?373X（2025）02?0029?06

A full?bridge LLC converter suitable for DC microgrid

GUO Mengzhu， CHEN Si， ZHENG Zhenyu， GUO Yongyu

（College of Elecrical and New Energy， China Three Gorges University， Yichang 443000， China）

Abstract： In allusion to the problems of large transformer volume， high loss and high voltage stress of semiconductor devices in traditional grid?connected isolated photovoltaic converter， a high?gain DC?DC converter based on LLC resonant converter is proposed. The converter can meet the requirements of electrical isolation between input and output. By combining the full?bridge LLC resonant converter with switching capacitors， the gain of the converter is increased effectively， the volume and loss of the transformer are reduced， the voltage stress of semiconductor device is lowered， and zero voltage switching of the switching tube and zero current switching of the diode are achieved， effectively reducing switching losses. The working principle of the proposed converter is analyzed in detail， its basic characteristics are analyzed by means of fundamental wave analysis method， and the voltage and current stress of semiconductor devices are calculated and the circuit parameters are designed. An 800 W experimental prototype is built to prove the accuracy of the theoretical analysis. The experimental verification that the converter can realize ZVS turn?on of the switching tube， ZCS turn?off of the diode， and reduce the volume and copper consumption of the transformer. The highest conversion efficiency can reach 94.9%. The voltage stress of the secondary diode is [12] of the output voltage， which is 0.5 times that of full bridge rectification， and 0.25 times that of half bridge rectification. The average current is the same， which is beneficial for the device selection and more suitable for the applications in DC microgrids， proving the accuracy of theoretical analysis.

Keywords： DC microgrid; LLC resonant converter; DC?DC converter; high gain; voltage stress; switching capacitor; fundamental wave analysis method

隨著傳統化石能源的枯竭以及全球環境問題的日益嚴重，光伏發電受到了世界各國的廣泛關注[1]，直流配電網相比交流配電網更便于分布式電源及清潔能源發電裝置的接入，因而更適應當今社會對電能的需求[2]。光伏直流并網作為一種有效的解決方案，受到越來越多的關注[3]，但光伏組件的固有特性并不滿足光伏并網的電壓需求，通常在光伏側與負載側之間配置電力電子變換器，是解決該問題的有效手段[4]。……