Simple method for measuring the equivalent series inductance and resistance of electrolytic capacitors

A simple equivalent series inductance (ESL) and equivalent series resistance (ESR) measurement technique for capacitors is presented. A low-cost square waveform voltage source coupled with a reference resistor can be used to measure the ESL, ESR and capacitance of an electrolytic capacitor. By connecting a capacitor in series with a reference resistor, the equivalent output step response of the capacitor voltage reveals the ESL and ESR of the capacitor. To effectively capture the output step response, a square input waveform is used instead. The square waveform voltage source can easily be realised using a DC voltage source and simple switching devices. Experimental results are included to demonstrate the effectiveness of the proposed scheme.