Integrator Design of the Rogowski Current Sensor for Detecting Fast Switch Current of SiC Devices

Accurate measurement of the switch current through a SiC device is especially challenging due to its fast switching speed and low junction capacitance. Its accompanied current sensor must hence have high bandwidth, strong noise-immunity, as well as a non-intrusive property. For these, the Rogowski current sensor (RCS) is particularly suitable. The RCS mainly consists of two parts, i.e. the Rogowski coil and the integrator. The integrator, whose functionality is to reconstruct the current from the output of the coil, is usually realized with an op-amp circuit for wider bandwidth. However, it may suffer from the DC offset, pre-shoot effect, and droop distortion, which has a significantly negative impact on the performance of the RCS. To alleviate these issues, this paper carries out a systematical study on the inverting and non-inverting active integrators of the RCS, and analyzes an improved non-inverting integrator (INII) in detail for detecting fast switch current of SiC devices. Both the theoretical analysis and experimental results show that the INII can enhance the accuracy of the RCS for detecting the switch current of SiC devices.