5kW全数字控制单级隔离型功率因数校正变换器的研究

Investigation of 5kW Fully Digital Controlled Single-stage Isolated PFC Converter

针对工业界某些场合对高功率等级、严格的谐波标准和隔离等要求,提出一种新的结合主电路和全数字控制技术的解决方案。文章采用单级隔离型全桥拓扑结合BOOST型PFC的输入电感和RCD溃能式箝位作为主电路,融合全数字控制,对中大功率单级隔离PFC进行研究。文中分析了主电路工作原理,建立了小信号动态模型,并给出数字控制设计方法。变压器的加入,不仅提供隔离功能且大大拓展了此类PFC变换器的应用场合。文中采用的数字控制方案具有良好的动态响应特性和稳态调节特性,并成功解决了模拟控制引入的变压器偏磁现象。基于该文所提出的拓扑以及控制方案,制作了5kW输出功率且PFC工作频率为55kHz的样机,验证了该变换器的优良性能,满载功率因数达到0.994,效率超过92%。

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 sing-stage （SS） full-bridge （FB） structure with input inductor 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 control strategy is introduced. The operation principle 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 galvanic isolation greatly extends the application of isolated 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%.