High-Bandwidth Embedded Rogowski Coil on Multilayer Substrate with Minimal Contribution to Power Loop Inductance

Power devices using GaN-HEMTs require high-bandwidth current sensors for fast switching current sensing, switch device protection and system control. PCB-embedded Rogowski coils are suitable for high frequency current sensing because they are electrically non-contact, have no magnetic core, and can be compactly mounted in the system. However, in conventional Rogowski coils, it is necessary to pass the current path through the center of the coil. This causes an extension of the current path, and consequently, an increase in parasitic inductance in the power loop of GaN-HEMT devices. In this paper, we propose a Rogowski coil consisting of a multilayer printed-circuit-board (PCB) substrate, which pick-up coil embedded in a laminated bus bar. The pick-up coil is also designed with microstrip lines to allow measurement of high-frequency current. Experimental results confirm that the bus bar of the proposed Rogowski coil exhibited low parasitic inductance and can detect high-frequency currents.