High-Bandwidth Combinational Rogowski Coil for SiC MOSFET Power Module

Existing current sensors suffer from insufficient measurement bandwidth or large insertion area to faithfully capture the continuous switching transient current of wide-bandgap devices. The combinational Rogowski coil concept is proposed here, where the self-integrating region of a shielded Rogowski coil is combined with its differentiating region to extend the overall measurement bandwidth. The coil design methodology, including the parasitic element model and practical design boundaries, is discussed. The concept is implemented with printed circuit boards and prototypes demonstrated up to 300 MHz bandwidth. The coil can also be easily integrated in an SiC
mosfet
module power stage and it is shown that the switching transient current waveform is faithfully captured.