5KW全数字控制单级隔离型功率因数校正变换器的研究

On The 5kW Digital Single-stage Isolated PFC Converter

针对当前工业界某些应用场合对高功率等级、严格的谐波标准以及输入输出隔离等要求,本文提出了一种新的结合主电路拓扑和全数字控制技术的解决方案。文章采用单级隔离型全桥结构结合传统BOOST型PFC的输入电感和RCD钳位作为主电路,并融合数字控制方案,对中大功率单级隔离型PFC进行研究。分析了主电路工作原理,建立了小信号动态模型,并详细分析了基于该模型的数字控制设计方法。提供输入输出电气隔离的变压器,允许输出可以在较大范围内调整,既可以高于输出电压也可以低于输出电压,此外允许多路输出方案。因此,变压器的加入大大拓展了此类PFC变换器的使用场合。采用的数字控制方案,同时具有良好的动态响应特性和稳态调节特性。优异的动态调节特性可成功解决模拟控制引入的变压器偏磁现象。基于本文所提出的拓扑以及控制方案,制作了5kW输出功率且开关频率为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 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 55kHz. Furthermore, such specifications as PF value and efficiency are respective 0.994 and more than 92%.