Self-Contained Wireless Hall Current Sensor Applied for Two-Wire Zip-Cords

A self-contained wireless current sensor applied for two-wire zip-cords is proposed in this paper, which consists of a Hall sensor, a wireless module, and an energy harvester along with the power management circuit. The energy harvester is constructed from a current transformer, where an EE-type magnetic core with two arms is specially designed by making a slit in one arm to produce unsymmetric field distributions: the field with low flux density is used for sensing and that with higher flux density for energy harvesting. In the energy scavenging operation, the sensor can generate 4.3 μW with a 217 Ω load resistor under 1 A zip-cord carrying current and supply power for the off-shelf Zig-bee nRF24LE1 wireless module to send one data for a time duration of about 5 min. In current-sensing operation, the sensor exhibits a sensitivity of 0.85 mV/A with a sensed current ranging from 1 A to 130 A.