Compact Interleaved PCB Rogowski Coil Array for Chip Current Measuring in SiC MOSFET Power Modules

The use of PCB Rogowski coils to measure chip currents in power modules may significantly help address current imbalance problems that lead to derating or overcurrent failure. Compared to silicon-based power devices, silicon carbide (SiC) power modules feature smaller chips and more compact chip arrangements, necessitating more compact current measuring probes. This paper proposes a novel design method for printed circuit board (PCB) Rogowski coil arrays that utilizes the interturn spacing to achieve an interleaved arrangement for Rogowski coils, thereby solving manufacturability problems while increasing the mutual inductance of the Rogowski coils. For a prototype SiC MOSFET power module, given the same spatial constraints, the coil array with the interleaved arrangement exhibits an average mutual inductance that is 98% higher than that of a coil array with the conventional arrangement. The circuit of the Rogowski transducer, consisting of the Rogowski coil and an integrator, is presented. The packaging processes for integrating the interleaved PCB Rogowski coil array into the power module are also described. The sensitivity of the Rogowski transducer is evaluated, and capacitive coupling interference is assessed. The switching currents of the 12 SiC MOSFET chips are measured using the interleaved PCB Rogowski coil array in a double pulse test, which reveals the detailed commutation behavior within the power module. The interleaved PCB Rogowski coil array proves to be an effective current measurement tool for densely arranged branches, providing a foundation for measuring the internal chip current distribution of power modules.