宽频域纹波环境下电解电容寿命模型建立及老化速率分析

Establishment of Life Model and Aging Rate Analysis of Electrolytic Capacitors in a Broad Frequency Range Ripple Environment

随着电力电子器件的兴起,其带来的宽频域开关次纹波使得电解电容愈发成为电路中至关重要的短板元件,建立宽频域环境下电解电容寿命预测模型有极大的必要性。现有的电解电容寿命预测模型大多仅考虑温升对电解电容寿命的影响,而未考虑宽频域纹波下电容容抗及其等效串联电阻大幅改变对电容热应力及其寿命的影响。本文以电解电容的宽频域模型为基础,建立了宽频域纹波环境下改进型电容寿命模型,该模型考虑了电容在宽频域纹波下容抗及其等效串联电阻的大幅改变,模拟了电容老化的动态过程。最后分别以SMD封装的22μF铝电解电容和钽电解电容为例,计算了宽频域下电解电容寿命预测值,并以铝电解电容为例,具体分析了频率影响电容寿命的机理。

With the rise of power electronic devices,the sub-ripple of broad frequency domain switch brought by it has made electrolytic capacitors more and more important components with shortcoming in circuits. It is extremely necessary to setup a life prediction model for electrolytic capacitors in a broad frequency domain environment. Most of the existing electrolytic capacitor life prediction models do not consider the influence of the large variation in the capacitive reactance and equivalent series resistance of the capacitor on the thermal stress and life of the capacitor under broad frequency ripple but the influence of temperature rise on the life of the electrolytic capacitor. The broad frequency domain model of electrolytic capacitors is taken as base in this paper,the improved capacitor life model under a broad frequency domain ripple environment is setup. This model takes into account the large variation in capacitance and equivalent series resistance of the capacitor under wide frequency domain ripple and simulates the dynamic process of capacitor aging. Finally,SMD packaged 22 μF aluminum electrolytic capacitors and tantalum electrolytic capacitors are taken as examples,the predicted value of electrolytic capacitor life in a broad frequency domain is calculated. And the aluminum electrolytic capacitors are taken as examples to analyze specifically the mechanism of frequency affecting capacitor life.