Why the 3 dB bandwidth of a current sensor does not provide an exact statement about its measurement capability

Abstract:
This work investigates the challenges for current measurement equipment due to the ever-increasing switching speed of power semiconductors. The investigation focuses on the influence of the different transfer characteristics of current sensors and the issues arising from using the 3 dB limit for comparison. The distinct transfer characteristics of sensors like current shunts and Rogowski coils and the resulting asymmetry in measurements are analyzed. The paper highlights the misconceptions about sensor quality, when following the current practice, as a higher 3 dB bandwidth does not necessarily correlate with a better performance. Two alternative approaches for a more decent comparison of current sensors are discussed.