单相Boost PFC变换器中电解电容的参数在线监测及寿命延长机理研究

Electrolytic capacitors usually determine the overall lifetime of single phase Boost PFC converter,which is widely used in the power supplier of electronic systems. The research focuses on online identifying and prolonging the lifetime of Electrolytic capacitors. The Boost PFC converter can be operated by four manners which are as follows: 1. the PF is unity and the capacitance is large; 2. to inject some harmonics into the input current; 3. to intentionally reduce the capacitanc; 4. to use active energy storage capacitor converter. Also, the inductor current has three modes such as CCM、CRM and DCM. Aiming at these cases, the relationship between the capacitor's current ripple and the input voltage, output voltage and power, input current ripple, pulsating voltage of the capacitor, is researched. Which is the basis for analyzing the heat dissipation and life time of capacitor. In addition, the method of identifying the parameter such as capacitance and equivalent series resistance (ESR) is stuydied and their degradation model with time is founded. Accordingly, the relationship between capacitor's lifetime and converter's electric parameter is analyzed and the requirements for prolonging lifetime is open out. Active energy storage inductor converter is proposed to replace electrolytic capacitor. The basic topology, design theory, control method and the volume and weight reduction of inductor is studied. Being very useful for life prediction and prolonging lifetime of power supply as well as the whole electronic system, the research is of great importance to promote the harmonious production and living way of enviromental protection.

单相Boost PFC变换器广泛存在于各类电子系统的供电电源中，其中电解电容的寿命最短，本项目研究其寿命在线监测及延长机理。针对PF值为1且电容值较大、输入电流中注入一定的谐波、有意减小电容值和采用有源储能电容变换器等四种情况，揭示不同的电感电流工作模式(CCM、CRM、DCM)下，电解电容的纹波电流与输入电压、输出电压、输出功率、输入电流谐波、电容电压脉动规律等因素之间的关系，为分析电容的发热及寿命提供依据。在此基础上，研究电容值C和等效串联电阻ESR的在线监测，进而建立C和ESR的时变模型，揭示电容寿命与变换器其他电气量的关系，找出各个情况下能使寿命延长的条件。为取代电解电容，提出有源储能电感变换器，研究其基本拓扑、设计原理及控制方法，分析如何降低电感体积和重量。本项目对于更好的掌握电源的使用寿命、延长电源乃至整个电子设备的使用期限，促进环保和谐的生产生活方式等，都具有重要意义。

电解电容是电源系统中最易失效的元件，其性能参数的退化直接影响系统的可靠性，因此在线监测其等效串联电阻ESR和电容值C的变化十分关键。本项目针对直流和交流变换器，提出了新的非侵入式在线监测输出电容ESR和C的方法。分析变换器输出电压交流分量，结合电容电流表达式和输入输出功率平衡，建立ESR和C的实时在线计算模型，设计了电容在线监测系统。所提方法为非侵入式，不改变变换器的电气结构，就可监测不同工作状态和各种温度下的ESR和C。推导了交流变换器中输入电流中含三次谐波时，电解电容纹波电流低频成分和高频成分有效值的表达式，并由此得出使电容纹波电流高频成分均方值最低的三次谐波及其占空比表达式，提出了一种使电解电容纹波电流有效值最低的控制方法，延长了电解电容的寿命。为简化实现电路，进一步提出一种拟合占空比控制方法。与传统控制相比，所提出的最低有效值控制还增大了临界电感值，减小了主功率器件的电流峰值及有效值，提高了变换器的效率。.研究成果解决了学术界和工业界存在的相关关键技术难题，促进了变换器“高功率因数、低谐波含量、高变换效率、高功率密度、高可靠性、长寿命”等的提升，对优化电源和相关电子产品性能、降低成本、节能减排等都具有重要意义。