Entropy characterisation of overstressed capacitors for lifetime prediction

[摘要] We propose a method to monitor the ageing and damage of capacitors based on their irreversible entropy generation rate. We overstressed several electrolytic capacitors in the range of 33 mu F-100 mu f and monitored their entropy generation rate (S)over dot (t). We found a strong relationship between capacitor degradation and (S)over dot(t). Therefore, we proposed a threshold for (S)over dot(t) as an indicator of capacitor time-to-failure. This magnitude is related to both capacitor parameters and to a damage indicator such as entropy. Our method goes beyond the typical statistical laws for lifetime prediction provided by manufacturers. We validated the model as a function of capacitance, geometry, and rated voltage. Moreover, we identified different failure modes, such as heating, electrolyte dry-up and gasification from the dependence of S(T) with temperature, T. Our method was implemented in cheap electrolytic capacitors but can be easily applied to any type of capacitor, supercapacitor, battery, or fuel cell. (C) 2016 Elsevier B.V. All rights reserved.

[发布日期] 2016-12-30

[关键词] Entropy;Capacitor;Joule effect;Reliability;Damage;Wear out;ESR;Ageing