Abstract

Aluminum electrolytic capacitor is one of the key components that restrict the life of DC-DC converter. Studying its deterioration analysis has advanced to realizing the prognostics and health management (PHM) technology of DC-DC converter. The main deterioration modes of aluminum electrolytic capacitor include the capacitance decrease and the equivalent series resistance (ESR) increases. These cause the ripple voltage to increase and eventually lead to the DC-DC converter failure. Some parameters of DC-DC converter (such as the ripple voltage, the ripple current, etc.) are selected as the feature signals of the aluminum electrolytic capacitor deterioration. By monitoring the changes of the feature signals, the aluminum electrolytic capacitor deterioration degree can be measured indirectly. Through theoretical analysis, this paper proposed a new idea to predict the remaining useful life (RUL) of DC-DC converter, that is, establishing the curve of the ripple voltage as the aluminum electrolytic capacitor deterioration and setting a warning point in the curve. When the change rate of the ripple voltage reached the warning point, the life of the DC-DC converter will come to an end. So, the RUL of the DC-DC converter can be predicted. In this paper, the buck converter is verified by simulation and physical experiments amid good agreements with the theory.

Key words: Aluminum electrolytic capacitor, DC-DC converter, deterioration, capacitance, equivalent series resistance (ESR), ripple voltage, remaining useful life (RUL), prognostics and health management (PHM).