Reference Setup for RF Impedance Measurements with High DC Bias Currents

This contribution discusses radio frequency impedance measurements of energy grid components under realistic operating conditions. These components, such as EMC filters or power electronic systems, draw high DC or low frequency operational currents. A reference setup which provides DC bias currents up to 200 A during the impedance measurement is introduced. The setup utilises automotive line impedance stabilisation networks, which feature a low-pass behaviour as well as a high current carrying capacity, for the decoupling between the power supply and the device under test. The performance of the proposed reference setup is assessed on the basis of measurements. Additionally, example measurements with contactless impedance analysis of different energy grid components, namely a high current air-core coil for EMC filters and an inverter test bench, are presented.