Design of high current broadband electromagnetic probe

Abstract

The current probe is a card type current sensor, which does not need to contact with the source wire. It can measure the high frequency interference current of the cable without disrupting the normal working state of the tested object. However, in the high-power system, the saturation of the probe and the amplitude of the high frequency interference are relatively small due to the large working current of the fundamental frequency. In order to meet the high frequency interference test of cable under high current condition, we need to improve the design of the current probe. Based on the physical structure of the probe, the equivalent circuit model of the probe is established, and the expression of the key index of the current probe, transmission impedance and insertion impedance, is derived. Starting from the model, the influence of magnetic core material, frequency and winding on the performance of the probe is analyzed. The design process of the current probe is proposed, and the design of the current probe with the effective bandwidth of 10~300MHz and the maximum test current of 100A and the inner diameter of 60mm is completed. The simulation analysis of the model is carried out by the electromagnetic simulation software. The simulation results are compared with the measured data of commercial probes in the market, and the performance of the designed probe is verified.