Design Methodology for Ultra-Compact Rogowski Coils for Current Sensing in Low-Voltage High-Current GaN Based DC/DC-Converters

This paper presents a design methodology, verified by measurements, of a differential Rogowski coil based compact, high bandwidth (> 500 MHz) PCB embedded current sensor for minimal invasive sensing (insertion inductance ≈ 200 pH) of transistor and phase currents in 48 V mild-hybrid Gallium Nitride based DC/DC-converters with paralleled transistors for high output currents. Two different sensor concepts with and without a planar shield are described and investigated. More than 30 designs with different winding number, structure and pitch are analyzed in 3D-finite element simulations. Finally, a standalone Rogowski-coil sensor for transistor current and a combination of a magnetoresistance sensor and a Rogowski-coil for phase output current measurements are presented.