Use of ESR to predict failure of output filtering capacitors in boost converters

This paper addresses the subject of fault diagnosis in boost converters, operating in continuous and in discontinuous mode, focusing particularly, in the output filtering electrolytic capacitors. The failure of those capacitor´s leads to an increase of their equivalent series resistance (ESR), and therefore, the efficiency decreases and the output voltage ripple increases. Two diagnostic methods are used, one is based on the relation between the mean values of the output voltage ripple and of the capacitor current ripple, both considered during the conduction time of the transistor, and the other is based on the relation between the value of the output voltage ripple for Ton/2 and the mean value of the output current. Several simulated and experimental results are presented for two DC-DC boost-type converters, one operating in the continuous mode and the other in the discontinuous mode.