Repulsive magnetic levitation-based ocean wave energy harvester with variable resonance: Modeling, simulation and experiment

Abstract

This paper investigates a magnetic levitation characteristic used in a vibration based energy harvester, called repulsive magnetic scavenger (RMS). The RMS is capable of harvesting ocean wave energy with a unique repelling permanent magnet array, which provides a stronger and more uniform magnetic field, compared to its attracting magnetic counterparts. The levitating magnets are stacked together around a threaded rod so that the same pole is facing each other. Two fixed magnets placed with one at each end of the RMS provides a collocated harvesting and braking mechanism in the face of high amplitude vibrations. Magnets in the levitated magnet stack are separated by pole pieces which are made of metals to intensify the magnetic field strength. The effect of the thickness and the use of different materials with different permeability for pole pieces is also studied to obtain an optimal energy harvesting efficiency. Moreover, the procedure to find the restoring force applied to the levitating magnet stack is demonstrated. Then, the Duffing vibration equation of the harvester is solved and the frequency response function is calculated for various force amplitudes and electrical damping so as to investigate the effect of these parameters on the response of the system. Furthermore, the effect of the maximum displacement of the moving magnet stack on the natural frequency of the device is studied. And finally, Faraday's law is employed to estimate the output voltage and power of the system under the specified input excitation force. Experiments show that the output emf voltage of the manufactured prototype reaches up to 42 V for an excitation force with the frequency of 9 Hz and the maximum amplitude of 3.4 g.

Nonlinear model and optimization method for a single-axis linear-motion energy harvester for footstep excitation

“…In contrast, our design makes use of a magnetic spring δ mag . This differs from other work in the literature that utilize a magnetic spring [11] [22] , as we utilize a single repelling magnet at the bottom of the device, as shown in Fig. 1.…”

“…This model is applied to the analysis of more complex configurations, thereby providing a means of optimizing the microgenerator design. It should be noted that despite sharing similar architecture features, the proposed model and optimization methodology differs significantly from those typically found in literature [22] due to the focus on harvesting energy from non-vibrational sources. Additionally, our approximate analytical model is in contrast to the use of first-principle electromagnetic techniques previously proposed [23] [24] and offers the advantage of much greater computational speed, once defined, in com-parison to performing a simulation with finite element analysis (FEA) due to the proposed model's parametric nature.…”

Multimodal Hybrid Piezoelectric-Electromagnetic Insole Energy Harvester Using PVDF Generators

“…The proposed HIEH can be modeled as lumped mass linear system, with the equation of motion for a harvester experiencing base excitations [33,53,54].…”

“…The proposed HIEH can be modeled as lumped mass linear system, with the equation of motion for a harvester experiencing base excitations [33,53,54]. In equation 1, is mass of the magnets, is the relative displacement between magnets and coils, is the restoring force (spring force, kz) on the moving magnets, and is the displacement of the harvester's base (frame).…”

Enhanced Bandwidth Nonlinear Resonance Electromagnetic Human Motion Energy Harvester Using Magnetic Springs and Ferrofluid

“…The harvester can be regarded as a nonlinear spring-damping vibrator system 3 that is excited by external motion. The dynamic model of the motion can be expressed as [31], [32]:…”