Measuring Parasitic Resistance of Resonant Converters Output Capacitor through Transfer Functions

Inhalt:
This paper describes how a measurement of the transfer function helps to determine changes in parasitic circuit components, namely the equivalent serial resistance of the output capacitor. An application of the method on a resonant converter demonstrates the procedure. A smart perturbation allows the measurement of the control to output transfer function. Similar, a model generates simulated results. Due to the high sensibility of the transfer function to the output filter, an accurate sensing of parasitic resistances is possible. Based on the results, the last part of the paper shows a direct calculation of the ESR using a simplified model.