Current measurement in static converters and realization of a high frequency passive current probe (50 A-300 MHz)

The measurement of currents in static power converters and specially the analysis of switching phenomena in semiconductor devices make necessary the use of current probe with large frequency bandwidth, high currents capability and low electromagnetic susceptibility. The first part of this paper concerns the description of current measurement techniques. The authors show why current transformer is a good way to measure current. An elementary structure based on a ferrite core, a winding and a resistor load is first tested. A high frequency electrical model is presented. It is used in the numerical simulation of the frequency response and allows one to pick the more significant parameters. The authors analyze one way of improving electrical performances and electromagnetic susceptibility. Then they show some experimental results obtained with such current probe