Influence Of DC / DC Converter Health Of Electrolytic Capacitor Failure Analysis

Electronic systems directly relate to national strategic security and national economicdevelopment, but their ftrquently failures due to the failure of the power system result in hugelosses. According to incomplete statistics, over34%of the electrotnic systems failures arecaused by the failure of power system. In order to enhance the reliability of electrolinic systemsworking in harsh environment, the prognostics and health management (PHM) technology ofpower system has become the common focus of attention in the international. The healthprediction for DC/DC converter is an important part of power PHM, and the health of DC/DCconverter is determined mainly by the output filter aluminum electrolytic capacitor. Therefore,studing the effect of aluminum electrolytic capacitor failure on the health of DC/DC converterhas great significance.This paper gives an overview of the significance of the effect of aluminum electrolyticcapacitor failure on the health of DC/DC converter, and introduces the research status at homeand abrord and the trend of the fault diagnosis on analog circuits, the PHM technology and thealuminum electrolytic capacitor failure analysis. The basic principles and major modeling ofDC/DC converter are described. Then using the switching elements average model sets up theequivalent circuit for Buck-Boost converter, and analyzes its steady-state and dynamiccharacteristics. The main failure modes of DC/DC converter are studied and the degradationfailure caused by the aluminum electrolytic capacitor is analyzed. The basic components, mianparameters, equivalent circuit and features of aluminum electrolytic capacitor are discussed,and the temperature and frequency characteristics of capacitance (C) and equivalent seriesresistance (ESR) are analyzed. The main failure modes of aluminum electrolytic capacitor andthe main reasons (C degradation and ESR degradation) caused aluminum electrolytic capacitordeterioration failure are discussed. Taking the small-signal standard circuit of DC/DC converterunder continuous current model (CCM) as the study object, the effect of aluminum electrolyticcapacitor deterioration failure on DC/DC converter output signal is analyzed based on thetheory of transfer function and system poles and zeros. Then, the derivation conclusions areverified through simulation and physical experiments based on Buck converter. Farther, the relationship between C and ripple voltage and the relationship between ESR and ripple voltageare given. A new combination deterioration model for aluminum electrolytic capacitor isestablished, and it is validated and corrected by off-line high temperature accelerated aging test.Basing on the new combination deterioration model, the effect of aluminum electrolyticcapacitor failure on the ripple voltage, the performances (such as stability margin,high-frequency anti-jamming capability, etc.) and the health of DC/DC converter is discussed.Then in Buck-Boost converter example, the theoretical analysis results are verified throughsimulation experiments. At the end of this paper, the reaearch is summarized and its furtherdirection is pointed out.