Life Prediction For Switching Power Supply Based On Key Components

With advantages of low dissipation, high power density, small size, light weight and fast response, switching power supplies are widely used in household appliances, telecommunications, broadcasting technology, transportation, industry, aerospace, military and other fields. Because of its responsibility for powering whole system, any failure occurrence will lead to huge economic losses, and even casualties in certain situations. Therefore, it is of great significance to conduct research on life prediction for switching power supply, thereby avoiding the catastrophic consequences effectively.In order to make life prediction for any individual switching power supply without aging or fault measured data of devices, a life prognostic approach based on aging mechanism and model of the key components is proposed, and it is a kind of White-box prognostic model.After the analysis of features and fault mechanism of key components in convertors, failures are mainly induced by the degradation due to components'ware out especially for well designed devices. And aluminum electrolytic capacitor ages the fastest and fails earliest among the key components, which severely limits the lifetime of the whole switching power supply. For learning the aging rule of aluminum electrolytic capacitors, this paper presents a new accelerated life test method for electrolytic capacitors by which the entire wear-out process could be finished within 100 hours and more aging data close to the end of the lifetime could be acquired. The proposed method was demonstrated by testing two types of commonly used aluminum electrolytic capacitors and a more universal model to describe the variation of the equivalent series resistance (ESR) with the electrolyte loss in aluminum electrolytic capacitors is established by analyzing the aging data. Meanwhile, for evaluating the ESR of electrolytic capacitors working in strong pulsed current condition, a new approach is presented and makes the measurement more effective since the test conditions are similar to capacitor's actual operating conditions. Then this paper presents an online ESR measurement approach for the output filter capacitor in convertors and establishes the online life prediction model for switching power supply which makes it available to estimate the remaining life time without power shutdown.The proposed life prediction method has two main advantages:1) Learning the aging rule of key components by experiments exempts the need to conduct aging test to whole convertors and obtain aging data, While ensuring accurate prediction results. 2) Life prediction model for other electronic devices can be established directly from the schematics with acquired prior knowledge of the components. This renders it convenient to apply this method to the life prediction of other similar devices.