Rectangular Busbar With Circular Sensing Part for Wideband Current Measurement

Abstract

A simple, reliable, and novel busbar sensing configuration for frequency-independent current measurement is presented in this article. Yokeless current transducers using arrays of magnetic sensors around a rectangular busbar are linear and lightweight, but they suffer from large frequency dependence. Several circular-array-based current transducers have been described in the literature, but their frequency characteristics have never been studied in detail. We show that the magnetic field surrounding a long circular busbar is frequency-independent, regardless of the surface effect. This feature can be used to develop an accurate circular-array-based coreless Hall current transducer for a wide range of frequencies. We propose a novel busbar configuration that has a 200-mm-long circular section in the current-sensing part of the busbar, which is compatible with the standard 10 x 60 mm rectangular busbar. A circular magnetic field sensor array is mounted in the midplane, around the circular conductor, for the current measurement. A finite-element method (FEM)-based 3-D analysis of the proposed busbar is performed with the help of an eddy current solver in the Ansys Maxwell tool. In addition, a prototype of the proposed wideband busbar was developed in the laboratory and its functionality was tested. The results that have been obtained show that the frequency dependence is reduced from -8.5% (for a rectangular busbar) to -0.45% (for the novel transducer).