GaN PCB Integrated Sensing System for Switch and Capacitor Currents

Gallium nitride (GaN) devices are often installed in a PCB based power electronic system. The parasitic inductance, the lack of galvanic isolation and the large size of existing PCB integrated current sensing techniques degrade the GaN system. Non-invasive giant magnetoresistive (GMR)-based current sensing systems have been integrated in power modules for closed-loop control. The GMRs have also been integrated in load inductors of wide bandgap (WBG) systems for MHz level current sensing. The prior researches haven't integrated GMRs in the PCBs for currents such as the switch and capacitor currents. To sense these PCB currents without degrading the original system, this paper introduces methodologies for GMR integration in the GaN PCBs. The multi-layer PCBs are divided into several basic structures that can be utilized for sensing. Based on the field properties of the basic structures, optimized detector layout of a multi-GMR sensing system can be decided to achieve accurate current sensing. Switch, DC-link capacitor and AC node currents in a GaN Systems evaluation board are experimentally sensed with the multi-GMR system. The methodologies can be readily applied to a variety of PCB based power converters for current sensing.