Maximizing Output Power Using a Magnetic Energy Harvesting System Considering the Relationship between Harvesting Time and Induced Voltage due to a Change of Airgap

Power transmission lines are equipped with various electronic devices, including power line inspection robots, safety sensors, and monitoring systems. However, providing power to devices installed on these lines often requires extensive construction and poses many challenges. Therefore, to solve such problems, active research is being conducted on Magnetic Energy Harvesters (MEHs) that harness the magnetic field generated by the current in the power lines to harvest electricity. A crucial design objective of the MEH is to maximize harvested power even if the saturated region is partially included, unlike a current transformer (CT), which must maintain an unsaturated state throughout the operating region. In this paper, design considerations of an MEH are discussed in comparison to the CT. Specifically, this paper formulates the relationship of the airgap between core cutting surfaces, the timing of power harvesting, and the amount of harvested power. It was observed that the MEH core should be designed to have a B-H curve close to the step function by minimizing the airgap and selecting magnetic material with high saturation magnetic flux density to achieve high harvesting power. An optimal MEH model for harvesting the maximum power for each given input current condition is presented. Furthermore, experiments were conducted to verify that 28 W of power was harvested under the input current condition of 150 Arms.