Energy Harvesting of Magnetic Power-Line Noise

The purpose of this study is to demonstrate the energy harvesting of power-line magnetic noise. To the best of the authors´ knowledge, no research has yet been carried out to confirm this possibility. In this paper, we present a simple circuit design model, and confirm its validity by experimental results. For small self-sufficient devices in a wireless sensor network, the target energy level is 1 mW. We prepare an energy harvesting module with an air-core coil and resonant capacitor. From experimental and simulated results, we investigate the desired conditions for harvesting 1 mW from a uniform magnetic field of 60 Hz. Through experimental results with iron cores, the benefits and drawbacks of the use of a magnetic core are also discussed. With our best harvested module, we successfully demonstrated the energy harvesting of 6.32 mW from a magnetic field of 21.2 μT at 60 Hz. If the usable magnetic flux density increases tenfold, the harvesting energy increased 100-fold. If the magnetic flux density is at an acceptable level in a public space of 200 μT at 60 Hz, the harvesting power density becomes 130 μW/cm³. This value is comparable to the value of an energy harvesting module of a light source during a cloudy day.