A Superpositioning Technique for Accurate Open-Type Current Sensing in Three-Phase Electrical Switchboards

Monitoring and analysis of power consumption are critical in terms of energy management, especially when managing the energy of factories with high energy consumption equipment. Hall sensors can be used for monitoring the power consumption. In this paper, we propose a novel superpositioning method for use with the three-phase current lines of an electrical switchboard, to improve the accuracy of current sensing by distinguishing the wanted magnetic field from magnetic interference. The relationship between magnetic interference and the magnetic field which we are trying to measure was investigated quantitatively by using numerical simulations as well as an experimental measurement. We subsequently designed a CMOS system-on-chip for use with magnetic Hall sensors, for practical validation of the proposed method. With this technique, measurement errors were less than ±0.8 %, based on experiments conducted with 50 A flowing through a three-phase current switchboard.