Capacitor aging detection in DC-DC converter output stage

One of the largest reliability issues in switching mode power supplies is capacitor aging based degradation. This paper proposes a step excitation based online capacitor wear-out detection method for output stage capacitor of a step down DC-DC converter. Changes in the converter output voltage dynamics are detected during operation by analyzing output voltage step response. Sensitivity of the presented method is evaluated with respect to component variations in converter main circuit. The feasibility of presented method is verified with experimental tests using a converter prototype. The results show, that the presented method is practical and adequate method for online capacitor degradation detection in various operating conditions.