Continuous calibration of Rogowski coil current transducer

Rogowski coils (RC) used for high-accuracy contact-less current measurement ask for precise sensor geometry and specific conditions, such as a centered primary conductor. To relax these constraints, we propose here a recently patented continuous calibration system which features a reference conductor added coaxially to the primary conductor and a proportional-integral controller integrated in CMOS technology. Experimental results obtained with commercial flexible and rigid RC show that the sensor immunity to the conductor position, as well as the dispersion between RC, is reduced to +/-0.1%, i.e. a 0.1 class measurement. In addition, the system may ensure an absolute calibration of the RC current transducer, avoiding any costly calibration procedure at the end of the sensor manufacturing.