Enabling Multiple Harvesting Windows in Magnetic Energy Harvesting via Reverse Flux Desaturation

Magnetic energy harvesting (MEH) leverages magnetic fields produced by ac current-carrying wires to harvest energy. This type of energy harvesting produces a relatively high volumetric energy density compared with other ambient energy harvesting methods, suitable for self-powering low-power devices such as embedded systems, sensor nodes, Internet-of-Things (IoT), and cyber-physical systems (CPS). Previous research works showed that the magnetic core should operate in an appropriately saturated state for maximal energy harvesting. Magnetic saturation is required in that magnetically stored energy in the physical volume of a core increases as the core is driven to saturation. However, the actual energy harvesting electrically ceases once the core reaches magnetic saturation. This article develops a new desaturation strategy that uses an opposite flux source and drives the core away from saturation as soon as it reaches saturation. This generates multiple energy harvesting windows in each cycle and greatly enhances the harvested energy via MEH. This article introduces multiple reverse flux desaturation mechanisms without complex circuitries. Circuit simulations and experiments are conducted to examine the effects of the load voltage and the number of energy harvesting windows on the amount of harvested energy. The results demonstrate that desaturation methods can double energy harvesting compared with conventional approaches without a desaturation scheme.