Impedance Measurement of Three-Phase Common-Mode Chokes in Power Electronic Applications

Three-phase common-mode (CM) choke presents a large demand from the industry to mitigate the undesirable conducted emissions in power electronic applications. Accurate impedance information of three-phase CM choke provides useful insights for its circuit modeling so that optimal filter can be designed to comply with the relevant electromagnetic compatibility (EMC) standards without the usual trial-and-error process. In this paper, a convenient strategy for three-phase choke impedance measurement is proposed. By conducting the four-terminal sensing technique and considering the non-ideal behaviors of open-short-load (OSL) calibration kits, the impedance of three-phase CM choke can be measured with good accuracy up to 30 MHz.