Real time monitoring of aging process in power converters using the SSTDR generated impedance matrix

A non-interfering measurement technique has been proposed in this paper to identify aging in various components in a power converter circuit. Several power MOSFETs and IGBTs were aged in a controlled environment, and spread spectrum time domain reflectometry (SSTDR) technique was applied to these components to determine the associated level of electrical degradation while they were connected in an energized circuit. Multiple impedance matrices have been created based on the measured reflection across multiple node pairs of the circuit, and these reflections are the true representations of the impedance across those node pairs. Therefore, these matrices provide key information about the level of electrical degradation associated to the core power components in the power circuit, and it is possible to predict the remaining life of the power converter by using this impedance matrices.