Using a sinosoidal PWM to estimate the ESR of Aluminum electrolytic capacitors

Abstract

This paper presents a very simple technique that can be used to estimate the capacitors equivalent series resistance (ESR) at their operating conditions. Aluminum electrolytic capacitors are one of the most critical components in switch mode power supplies and in adjustable speed drives; yet, they are the preferred choice in those applications. The ESR changes considerably with frequency, temperature and ageing; besides the information given by manufactures is scarce.