Measurement and analysis of low-frequency noise in large capacity high voltage aluminum electrolytic capacitors

The testing technique of low-frequency noise in electrolytic capacitors was presented. Using this method the time series and power spectra of low-frequency noise under room temperature and the dependences of power spectra on both terminal voltages and temperatures were measured. The results showed that the low-frequency noise in aluminum electrolytic capacitors was 1/f noise in the frequency range from 0.1 Hz to 30 Hz. The variation curves of extracted noise power spectra densities at 1 Hz with biases and temperatures agree well with theoretical analyses. The low-frequency noise characterization method presented in this paper will render a solid basis for both the investigation of low-frequency noise and the establishment of low-frequency based nondestructive inspection schemes for electrolytic capacitors.