ENERGY HARVESTING
Magnetic Field Energy Harvesting
Energy Harvesting from Stray Magnetic Field for Smart Infrastructure
Magnetic field exists everywhere in modern life as electrically operating objects always generate the magnetic field according to Maxwell-Faraday relation in electromagnetism. Up to now the stray magnetic field has been considered as a noise radiation causing malfunction of the electronics but it can be useful ubiquitous free energy source. In particular, there is plenty of magnetic noise in infrastructures, produced by appliances, lightings, power cables, etc. The goal of this research topic is to scavenge wasted magnetic field energy and convert into the electricity in order to provide sustainable power source for Internet of (IoT) sensors and wireless communication system in smart home and smart factory. Energy conversion from the magnetic field into the electricity is not a new technology. Commercially available radio frequency (RF) antenna and induction coils efficiently converts the RF magnetic field into the electric power. However, their energy conversion efficiency tends to be dramatically degraded at low frequency (50/60 Hz) that is dominant magnetic noise in the infrastructure. We focuses on finding answers for how to design the energy conversion device to achieve high energy conversion efficiency in low frequency and low amplitude magnetic field. To demonstrate efficient energy conversion device operating in the low-grade stray magnetic field, we study on magnetoelectric (ME) coupled magneto-mechano-electric (MME) energy conversion mechanism and demonstrate outstanding ME coupled MME generator comprised of piezoelectric and magnetostrictive materials.
Distributed forcing architecture for enhancing power generation
Energy harvesting from extremely low frequency magnetic fields using magneto-mechano-electric (MME) harvesters enables wireless power transfer for operating Internet of Thing (IoT) devices. The MME harvesters are designed to resonate at a fixed frequency by absorbing AC magnetic fields through a composite cantilever comprising of piezoelectric and magnetostrictive materials, and a permanent magnetic tip mass. However, this harvester architecture limits power generation because volume of the magnetic end mass is closely coupled with the resonance frequency of the device structure. Here, we demonstrate a method for maintaining the resonance frequency of the MME harvesters under all operating conditions (e.g. 60 Hz, standard frequency of electricity in many countries) while simultaneously enhancing the output power generation. By distributing the magnetic mass over the beam, the output power of the harvester is significantly enhanced at a constant resonance frequency. The MME harvester with distributed forcing shows 280% improvement in the power generation compared with a traditional architecture. The generated power is shown to be sufficient to power eight different onboard sensors with wireless data transmission integrated on a drone. These results demonstrate the promise of MME energy harvesters for powering wireless communication and Internet of Things (IoT) sensors.
