Optimization of Core Size and Harvested Power for Magnetic Energy Harvesters based on Cascaded Magnetics

Magnetic energy harvesting (MEH) extracts energy from magnetic fields generated from AC current, providing power for environmental sensors, Internet of Things (IoTs), and monitoring nodes. The cascaded-magnetic-based electromagnetic energy harvesters, consisting of a clampable core and a high-permeability ungapped core, feature relatively higher density and predictability in energy harvesting. The clampable core only facilitates a non-intrusive mounting of the energy harvester onto the primary wire while the high-permeability core is the heart of the energy harvester to guarantee the maximum power extraction and usable output voltage. Therefore, reducing the clampable core size is critical to increase the power density without drastic power degradation. This article first presents the optimization conditions of the clampable core volume based on the harvested power level and other design requirements. FEM simulations using Ansys Maxwell and LTspice simulations are both executed to show the influence of the core parameters on the amount of harvested power and core saturation. This paper also presents an energy improvement method, controlling power transfer window via active switches, to improve the harvested power level. The boosted power is evaluated in this paper via experimental results.