AC characteristics of low-ohmic foil shunts influenced by eddy currents in the mounting body

Abstract

The requirements for precision current-sensing shunts are getting more sophisticated due to further development of fast switch-mode converters and other high-frequency applications. Good AC characteristics are important both for industrial applications and for calibration standard purposes. Low-ohmic foil shunts show excellent DC behavior, but the AC characteristics could be improved. The optimization of foil shunts towards better temperature independency and load stability in the range of a few parts per million per kelvin can lead to significant weaker AC performance. In this work, eddy currents in the mounting body are identified as a cause of the increasing real part of the shunt impedance at higher frequencies by means of a numerical field simulation.