Design of PCB Rogowski Coil Current Sensor With Low Droop Distortion

Abstract

Wide bandgap devices (SiC and GaN) bring the potential for a great increase in power density of power electronics, but also pose a challenge to the bandwidth of the current sensor because of the high operating frequency. Rogowski coil is suitable for high-frequency current measurement due to its characteristic of differential output, but the existing design is difficult to take into account the sensitivity and mutual inductance at the same time, and faces the inherent defect of droop distortion. This article proposes an optimal printed circuit board (PCB) Rogowski coil structure design method for SiC MOSFET power module and a novel sample-filter-hold (SFH) method to minimize droop distortion in integrators. First, the optimal parameters with multiobjective constrained optimization of the Rogowski coil current sensor for the SiC-MOSFET power module are obtained. Then, the influence factors of droop distortion of the sensor in buck converters and inverters are quantitatively analyzed for the first time and an SFH suppression method is proposed, which can eliminate the offset caused by droop distortion reliably and accurately. Finally, the experimental results demonstrate that the proposed Rogowski coil design method and the SFH method for lower droop distortion achieve better low-frequency performance compared to the commercial Rogowski coil.