A two-dimensional electromagnetic vibration energy harvester with variable stiffness. (1st November 2022)

• Record Type: Journal Article
• Authors: Imbaquingo, Carlos; Bahl, Christian; Insinga, Andrea R.; Bjørk, Rasmus
• Is Part Of: Applied energy. Volume 325(2022)
• Publication Date: 2022-11-01
• Subjects: Electromagnetic energy harvester -- 2D electromagnetic harvester -- Two-dimensional vibration -- Variable stiffness -- Magnetic stiffness; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2022.119650
• Languages: English
• ISSNs: 0306-2619

Abstract

Abstract: This work investigates the performance of an electromagnetic vibration harvester for two-dimensional vibrations with variable magnetic stiffness and electromagnetic damping. The device consists of a free-to-move cylindrical magnetic structure with a set of bearings located on top and bottom, a couple of coils located on top and bottom of the device and finally a fixed system of disk-shaped magnets placed inside a ring holder. The number of disk-shaped magnets in the ring holder can be varied to change the magnetic stiffness of the system. The performance of the device is characterized experimentally for nine different configurations of disk-shaped magnets, exploring both symmetric and asymmetric designs. Using an XY-shaker to vibrate the system in two dimensions in frequencies from 1 Hz to 10 Hz and with motion amplitude of 2 mm on both axes, a maximum power of 27 mW was harvested. This occurs for an asymmetric device, i.e. with different magnetic stiffnesses along its two axis. For symmetric devices the power is lower by a factor of two. Finally, varying the electromagnetic damping, which is controlled by varying the coil dimensions, can further increase the power to 42 mW. Highlights: A two-dimensional electromagnetic energy harvester is presented that can harvest energy from 2D vibrations. The harvester is made asymmetric using different arrangements of permanent magnets. The power harvested for different magnetic stiffnesses are characterized as function of frequencies in different directions. The resonance frequency are shown to depend on the magnetic stiffness. The harvester produces up to 42 mW of power from 2D vibrations.