Trigger based online monitor for buck converter output capacitor′s ESR

Abstract

Electrolytic capacitor as filter capacitor is widely used in switching power module, but it has higher failure rate than other components. In order to monitor the status of the electrolytic capacitor, the equivalent series resistance(ESR) is selected as monitoring target. This paper presents an online monitor method for buck converter output capacitor’s ESR and capacity value, by sampling output voltage at falling edges and rising edges of switching signal. The effectiveness of the proposed method is verified by the experimental system. The proposed method avoids measuring inductor current that simplifies the trigger circuit structure and keeps the topology of the switching power supply module, which facilitates a wide range of applications.

Keywords

• electrolytic capacitor
• equivalent series resistance
• switching power
• fault diagnosis