Capacitor loss analysis method for power electronics converters

A capacitor is a major component that contributes to reducing the reliability of high-power density power electronics converters. The lifetime and reliability of capacitors are strongly influenced by temperature. An accurate loss measurement method is necessary to estimate temperature rise. However, practical capacitor loss measurement systems used in power electronics converters have not yet been developed because capacitor loss data provided by the manufacturer is usually measured under sinusoidal excitation, which is different from actual excitations of electronics converters. In this study, a capacitor loss measurement system for power electronics converters is proposed. The proposed measurement system can be used for fast capacitor loss measurement with high accuracy in a real circuit and capacitor loss analysis for each switching period of power electronics converters. To verify the accuracy of the loss measurement, the measured loss value of a filter capacitor used in a pulse width modulated inverter is compared with the calculated value. The experimental results show good agreement with the calculated capacitor loss.