Realization of a smart electrolytic capacitor circuit

The object of this paper is to present an economic electronic module integrated on an electrolytic capacitor that is able to indicate the moment when it must be changed. First, with a switchmode power supply as an example, the high probability of electrolytic capacitor failure with respect to other power components is noted. Second, the authors recall that the increase of the equivalent series resistance (ESR) of the capacitor is the best indicator of their faulty state. From the measurements of the voltage ripple and the capacitor current, one can deduce the ESR; the latter is compared to the ESR value of the sound capacitor deduced from the component case temperature. Thus, the capacitor deterioration can be diagnosed.