High-efficiency magnetic field energy harvesting from a three-core cable

Alternating magnetic fields generated by ac power lines are renewable energy sources that can be scavenged by magnetic energy harvesting cores for wireless sensor networks (WSNs). However, traditional magnetic cores are suffering from low efficiency when applied to three-core cables. This paper systematically analyzed the characteristics of the magnetic induction intensity of a three-core cable by finite element methods (FEM), figured out the optimal energy harvesting position, innovatively designed and fabricated a novel notched ring core (NNRC) to better match the magnetic field characteristics of three-core cables. Compared with the previously reported core, the NNRC has 2.3 times the output voltage per turn and more space allowance for winding coil. According to experimental results, the open-circuit output voltage amplitude of NNRC was 16.6 V with 9000 turns of wire and 100 AAMP ac current in each phase of the cable. Finally, a non-controlled AC/DC circuit was applied and 28.4 mW maximum dc power was obtained.