A study on electrolytic capacitor aging in power converters and parameter change over the lifespan

Abstract

Electrolytic capacitor is a very common element used in modern power electronics. Besides the undoubtable advantages as high capacity per volume and low price per capacity unit, they are relatively low reliability and limited lifetime. This paper describes the aging mechanisms, change of parameters over time and process of artificial ageing of electrolytic capacitors. The accelerated aging of these elements helps to discover the boundaries of ESR growth and degradation of capacitance in comparison to initial values, how changes the bode diagram of impedance over aging. The obtained data is useful for development of diagnostic algorithms for power converters, design considerations for high reliability designs and better understanding of lifetime estimation of electronic devices. The paper contains the data obtained from real tests made with electrolytic capacitors of small values as an example. Capacitor accelerated ageing is made using overtemperature and overvoltage, the process is alternated with tests of parameters to fully illustrate the processes expected in future designs.