Expiry Date for Power Supply? Sensor-less Life Prediction of Switching Power Supply

Abstract

Power supply is a critical component in all electronic products. Unexpected failure of a power supply may lead to enormous consequential loss. However life prediction of a power supply has never been accurate because the electronic component life varies greatly with operating conditions. Among the electronic parts in a power supply the electrolytic capacitor is the weakest. The power supply life can be predicted by the life of the electrolytic capacitor. To predict the life of the electrolytic capacitor the ripple current must be known. The present work proposes a sensor-less life prediction method for switching power supply. The popular current mode control platform makes the power converter switching current available. The current is digitized by a novel method that requires no expensive high speed ADC or sample and hold device. The capacitor ripple current is then computed in real time and the result is presented through a pulsating signal channel. Experiments on AC to DC forward converter and flyback converter are presented. Favorable comparison with direct measurement verified the method.