A Broadband Hybrid Rogowski Coil Sensor Based on Comparative Study of Operating Modes for Switching Transient Measurement

Rogowski coil sensors, characterized by high bandwidth, non-saturating behavior, and non-invasive measurement, have become essential mainstream devices for the development, testing, and application of wide-bandgap semiconductor power devices. The simultaneous optimization of their low-frequency and high-frequency cut-off characteristics requires a systematic engineering approach that regards the coil and integrator as an integrated measurement chain. This paper presents a comparative analysis of three typical operating modes of Rogowski coils - differential mode, self-integrating mode, and transmission line mode - regarding bandwidth, phase response, output voltage, and other key performance indicators. A hybrid Rogowski coil sensor is then proposed, combining the high-output advantage of the differential mode with the high-bandwidth merit of the self-integrating mode, achieving an extended operating bandwidth from 6.8 kHz to 485.5 MHz. Finally, the performance of the sensor prototype is verified through double-pulse tests, which validate its ability to accurately capture the switching current waveforms of SiC MOSFETs.