Characterization of power electronics system interconnect parasitics using time domain reflectometry

The significance of interconnect parasitics of power electronics systems is their effects on converters' EMI-related performances, such as voltage/current spikes, dv/dt, di/dt, conducted/radiated EMI noise, and the like. In this paper, a time domain reflectometry (TDR) measurement-based modeling technique is described for characterizing interconnect parasitics in switching power converters. Experiments are conducted on power components of a prototype high-power inverter, including IGBT modules, busbar, and bulk capacitors. It is shown that the interconnect inductance of the IGBT module can be extracted completely using TDR. It is also shown that the busbar equivalent circuit model can be partitioned into transmission line segments or L-C filter sections, and the bulk capacitor contains a significant equivalent series interconnect inductance.