5KW全數字控制單級隔離型功率因數校正變換器的研究

摘要：針對當前工業界某些應用場合對高功率等級、嚴格的諧波標準以及輸入輸出隔離等要求，本文提出了一種新的結合主電路拓撲和全數字控制技術的解決方案。文章采用單級隔離型全橋結構結合傳統BOOST型PFC的輸入電感和RCD鉗位作為主電路，并融合數字控制方案，對中大功率單級隔離型PFC進行研究。分析了主電路工作原理，建立了小信號動態模型，并詳細分析了基于該模型的數字控制設計方法。提供輸入輸出電氣隔離的變壓器，允許輸出可以在較大范圍內調整，既可以高于輸出電壓也可以低于輸出電壓，此外允許多路輸出方案。因此，變壓器的加入大大拓展了此類PFC變換器的使用場合。采用的數字控制方案，同時具有良好的動態響應特性和穩態調節特性。優異的動態調節特性可成功解決模擬控制引入的變壓器偏磁現象�；�于本文所提出的拓撲以及控制方案，制作了5kW輸出功率且開關頻率為55kHz的樣機，驗證了該變換器的優良性能，滿載功率因數達到0.994，效率超過92%。 敘詞：單級隔離 全橋 功率因數校正 偏磁 數字控制 Abstract：Dedicated to industry requirement of high power level, rigorous harmonic standard and isolation between input and output, a novel solution that combines the main topology and fully digital control strategy is presented in this paper. This paper deals with a power factor correction (PFC) converter based on the topology of isolated of BOOST type PFC and RCD clamping circuit, which features that clamping capacitor can partly return stored energy and that contributes to increase efficiency, furthermore fully digital and its digital control design consideration based on the small-signal dynamic mathematical model of the very converter are respectively specified in this paper. A transformer being used to provide PFC converter. The adopted digital control strategy features fast dynamic response and excellent steady regulation characteristic. Problem of magnetic bias for the transformer that occurs in application of analogy control is successfully solved for excellent performance of digital controller. The above excellent performances of the converter are verified by an experimental prototype, whose output power is 5KW and PFC operation frequency is 55K. Furthermore, such specifications as PF value and efficiency are respective 0.994 and more than 92%. Keyword：Single-stage isolated, full-bridge, power factor correction, magnetic bias, digital control