Design of a 1 ampere high-precision thin-film resistive current transducer with negligible frequency dependence from DC to 100 KHz

Abstract

Currently, non-linear loads are found virtually anywhere with the promise of high electrical efficiency. Examples of this type of non-linear loads are compact fluorescent lamps and light-emitting diode lamps which can now be found in any home. However, they produce highly distorted currents that pollute the power grid and cause stability problems, and making the measurement of the distorted electrical current a non-trivial issue. For the reliable measurement of distorted waveforms within a wide bandwidth, magnetic current transducers present disadvantages over resistive current transducers, such as those caused by the magnetic material which attenuates the high-frequency components while producing heating on the magnetic material. This research presents the design principles to develop a thin-film wideband current transducer. Principles such as the selection of high-purity materials, high-symmetry coaxial design, size, geometry, and aspect ratios were used to obtain a linear relationship between its input and output, i.e.: a flat frequency response from DC to 100 kHz, and the ability to operate continuously with a custom passive thermal system for heat dissipation and reliable measurement. An exhaustive effort has been made on the refinement of the design aimed at understanding the effects that govern the frequency behavior of the transducer and the ways to compensate them. The manufacturing feasibility of the proposed design is well confirmed by the results obtained from the simulation process.