Failure prediction of electrolytic capacitors during operation of aswitchmode power supply

摘要

Electrolytic filter capacitors are frequently responsible fornstatic converter breakdowns. To predict these faults, a new method tonset a predictive maintenance is presented and tested on two types ofnconverters. The best indicator of fault of the output filter capacitorsnis the increase of ESR (equivalent series resistance). Thenoutput-voltage ripple ΔVo of the converter increasesnwith respect to ESR. In order to avoid errors due to load variations,nΔVo is filtered at the switching frequency of thenconverter. The problem is that this filtered component is not onlyndependent on the aging of the capacitors, but also on the ambientntemperature, output current, and input voltage of the converter. Thus,nto predict the failure of the capacitors, this component is processednwith these parameters and the remaining time before failure is deduced.nSoftware was developed to establish predictive maintenance of thenconverter. The method developed is as follows. First, a reference systemnincluding all the converter parameters was built for the converter atnits sound state, i.e., using sound electrolytic filter capacitors. Then,nall these parameters were processed and compared on line to thenreference system, thereby, the lifetime of these capacitors was computed