An Online Monitoring Scheme of Output Capacitor's Equivalent Series Resistance for Buck Converters Without Current Sensors
Xiaoxing Duan, Jian Zou, Bin Li, Zhaohui Wu, Dengyun Lei
Abstract
Aluminum electrolytic capacitors are widely used in switching mode power supply as smoothing capacitor, but they are the weakest among power components in dc–dc converter. It is very important to monitor its electrical parameters, mainly the equivalent series resistance (ESR). A monitoring method of capacitor's ESR for buck converters is proposed in this article. Based on the calculation model of ESR, the target parameter is monitored by sampling output ripple voltage. The proposed method needs no current sensor. Whether the circuit is in continuous conduction mode or discontinuous conduction mode, it is convenient to monitor the capacitor. Implementation of the monitoring system is presented. The experimental results validate the effectiveness of the method.