Magnetic flux concentration methods for magnetic energy harvesting module

Abstract

Abstract. This paper presents magnetic flux concentration methods for magnetic energy harvesting module. The purpose of this study is to harvest 1 mW energy with a Brooks coil 2 cm in diameter from environmental magnetic field at 60 Hz. Because the harvesting power is proportional to the square of the magnetic flux density, we consider the use of a magnetic flux concentration coil and a magnetic core. The magnetic flux concentration coil consists of an aircore Brooks coil and a resonant capacitor. When a uniform magnetic field crossed the coil, the magnetic flux distribution around the coil was changed. It is found that the magnetic field in an area is concentrated larger than 20 times compared with the uniform magnetic field. Compared with the aircore coil, our designed magnetic core makes the harvested energy tenfold. According to ICNIRP2010 guideline, the acceptable level of magnetic field is 0.2 mT in the frequency range between 25 Hz and 400 Hz. Without the two magnetic flux concentration methods, the corresponding energy is limited to 1 µW. In contrast, our experimental results successfully demonstrate energy harvesting of 1 mW from a magnetic field of 0.03 mT at 60 Hz.

Leakage Flux Recovery Coil for Energy Harvesting Using Magnetoplated Wire

“…The electrical power collected from leakage magnetic flux is proportional to the quality factor of the leakage flux recovery coil [4]. However, the AC resistance increases due to the skin effect and a proximity effect when the magnetic flux crosses a coil.…”

“…V is the induced voltage when the magnetic flux that crosses the coil. L and R is the inductance and resistance of the coil, respectively R L is the output resistance and that is connected to the coil and to capacitor C. From Faraday's law, the induced voltage V of the leakage flux recovery coil is given by (1) [4].…”

Design of magnetic field alarm powered by magnetic energy harvesting

“…It may enough energy to activate a wireless sensor node, and "oneshot" signal. It was also mentioned the benefit of magnetic flux concentration core [11]. The theoretical design have revealed that the harvesting power is proportional to the fifth power of the outer diameter [12].…”

Estimation of Effective Permeability for Dumbbell-Shaped Magnetic Cores

“…Because the target is a weak magnetic field defined by ICNIRP2010 guideline, magnetic flux concentration methods are key techniques. In previous report, the importance of magnetic flux concentration core and coil was experimentally demonstrated [3]. The harvesting power is proportional to the square of the magnetic flux density, therefore it is very important to design the effective permeability of the core defined by the concentration ratio of magnetic flux density to the coil.…”