A Health Indicator of Aluminum Electrolytic Capacitors Based on Strain Sensing

This letter proposes a novel health indicator for aluminum electrolytic capacitors (AECs) based on strain sensing in a nonintrusive manner. The indicator leverages the mechanism that the internal pressure of AECs gradually increases with the electrochemical reaction caused by degradation, thereby, with a change in strain. The results reveal the proposed health indicator is highly sensitive to capacitor degradation and meanwhile highly resistant to interferences. Furthermore, an end-of-life criterion for the AECs is proposed in this indicator, which is corresponding to the moment of open vent. The applicability of this indicator is verified for constant conditions, dynamic operating conditions, and overvoltage conditions. In addition, the effect of temperature is analyzed. The proposed health indicator can be used to determine the time to failure of testing samples in accelerated life testing and condition monitoring of AECs.