An improved Rogowski coil configuration for a high speed, compact current sensor with high immunity to voltage transients

Abstract

Rogowski current transducers are often used to measure transient and pulsed currents in power electronic applications. They are small, clip-around and flexible making them easy to insert in circuits with a high power density, have a wide-bandwidth, and negligible insertion impedance. Recent advances in GaN and SiC semiconductor switches mean that the next generation of Rogowski transducers need to have: •Higher temperature operation. •Better high frequency bandwidth, enabling measurement of of rise times of 5–20ns with good fidelity and a predictable measurement delay for power measurements. •Improved rejection of common mode interference from close coupled capacitive interference due to voltage transients >20V/ns, whilst retaining high frequency capability and accuracy with conductor position in the sensor loop. •Size reduction as semiconductor package sizes shrink. The aim of this paper is to examine the relative advantages of screened and unscreened Rogowski coils and to show that screened coils are capable of providing the high bandwidths and noise immunity required for semiconductor switching current measurements.