The Korea Institute of Industrial Technology (KITECH) has developed a new energy harvesting technology that converts magnetic fields around power lines into electricity. This allows devices like drones and sensors, which are challenging to charge in external environments, to be powered more easily.
On the 9th, KITECH’s Energy Nano Group, led by Senior Researcher Yoon Seung-ha, announced their success in implementing a new energy harvesting method that effectively collects circular magnetic fields around power lines.
The core of this technology lies in the application of a symmetrical vibration structure based on central fixation and magnets on both sides. Magnetic field-based energy harvesting works by altering the force applied to a magnet connected to piezoelectric material as the intensity or direction of the magnetic field changes. This, in turn, causes the piezoelectric material to bend, generating electricity. Piezoelectric materials generate electricity when mechanically deformed, such as being pressed or bent.
The more frequently the piezoelectric material bends, the greater the electricity generation, maintaining output. Therefore, inducing sufficient deformation in a resonant state is crucial.
The newly developed magnetic energy harvesting module was designed to position a magnet on one side, while keeping the piezoelectric material fixed on the other, allowing it to move due to external magnetic fields.
Further optimizing this basic structure, the research team considered the alternating circular magnetic fields around power lines that continually push and pull the magnets. They developed a module with a symmetrical vibration structure to maintain the piezoelectric resonant state.
In this design, they fixed the piezo in the center and placed permanent magnets with opposing polarities on either side. When the direction of the magnetic field changes around the power lines, both magnets move in the same direction, doubling the electricity production compared to the traditional method using a single magnet and piezo.
Additionally, they used a Magnetic Flux Concentrator (MFC) to increase the force transmitted to the magnets even in weak magnetic fields, enhancing power conversion efficiency per unit area of piezo by over 20%.
To verify the structure, the team simulated a magnetic environment similar to that around power lines, using less than 10 Gauss with Helmholtz coils. Experiments showed the developed harvester could secure 25.2 mW/cm³ of power in weak magnetic fields of about 5.4 Gauss near power lines.
This achievement, documented in a paper titled “Energy harvesting with magneto-mechano-electric harvester for AC circular magnetic fields,” was supported by a representative project of KITECH and secured two domestic patents. It was published in the international journal ‘Sensors and Actuators A: Physical.’
Senior Researcher Yoon Seung-ha stated, “This technology can convert weak magnetic fields near power lines into power. We plan to apply it to devices like IoT sensors and miniature drones, which are difficult to charge in external environments, for continuous operation self-powered technology development.”