Characterization of Conventional and Advanced Current Measurement Techniques Suitable for WBG Semiconductor Devices

With wide bandgap semiconductor devices, conventional current sensors like Rogowski coils and coaxial shunts reach their limits in bandwidth or parasitic inductance. Therefore, novel techniques are continuously being developed, which promise improved characteristics. In order to evaluate the performance of current sensors, it is necessary to compare them in a uniform environment. In this work, different sensors for currents up to 100 A and frequencies of several 100 MHz are characterized in the frequency- and time-domain. The characteristics bandwidth, parasitic inductance and delay are determined by measurement and compared to each other. Among the advanced measurement techniques is a design consisting of coaxially arranged discrete resistors. A prototype is built based on this idea and tested against the other sensors. The prototype outperforms the conventional sensors and is validated in a double pulse test with Gallium nitride devices.