High-Bandwidth Shielded Rogowski Coil Current Sensor for SiC MOSFET Power Module

Existing current sensors suffer from insufficient measurement bandwidth or large insertion area to continuously monitor the switching transient current of wide-bandgap devices. A combinational Rogowski coil concept is proposed here, where the self-integrating region of a shielded Rogowski coil is combined with its differentiating region. The overall measurement bandwidth is effectively extended by the self-integrating region. The design methodology for the shielded Rogowski coil, especially the parasitic elements and error analysis, is discussed. Finally, a prototype is demonstrated with a sensitivity is 5.0 mΩ and a bandwidth of 200 MHz. The measurement in a SiC power module double pulse shows it can faithfully capture the transient current while introducing little interference.