Switch current measurement of SiC device based on twisted-pair four-layer PCB Rogowski coil

Abstract

To solve the problem of electromagnetic interference affecting the measurement accuracy of switching current measurement of silicon carbide (SiC) devices, a twisted-pair four-layer printed circuit board (PCB) Rogowski coil with strong immunity and high bandwidth is proposed. Firstly, based on the physical and electrical characteristics of SiC devices, the requirements of current sensors for switching current measurement were analyzed, which has higher bandwidth, stronger immunity, and lower intrusion in the measurement process. Secondly, the anti-interference principle of PCB Rogowski coil was analyzed, and the mechanism of the return wire and screen against magnetic and electric field interference was expounded. Then, the disturbance resistance of three typical PCB Rogowski coils (two-layer, four-layer and six-layer PCB Rogowski coils) was analyzed. Based on this, a twisted-pair PCB Rogowski coil was proposed. The scheme adopted a four-layer PCB design. The middle two layers were twisted-pair structure, while the outer two layers were grounded shielding. Simulation and experimental results show that the proposed scheme has strong disturbance immunity and high bandwidth characteristics, which is suitable for measuring the switch current of SiC devices.