An Online Monitoring Scheme of Output Capacitor’s ESR for DCM Buck

Abstract

Electrolytic capacitor is widely selected as output capacitor in DC-DC converter, while it has limited reliability. Monitoring the equivalent series resistance (ESR) is an effective method to diagnostic the output capacitor. In this paper, an online monitoring scheme of ESR is present for discontinuous conduction mode (DCM) Buck converters. Based on the output ripple voltage, the model of ESR is established. By sampling the output ripple voltage, the ESR is calculated using the sampled values. The proposed method reduces the current measurement and avoids the change of converter topology. The simulation and experimental results verify the effectiveness of the method.