An experimental study of a two‐degree‐of‐freedom galloping energy harvester

2020 ◽  
Author(s):  
Guobiao Hu ◽  
Junlei Wang ◽  
Hongwei Qiao ◽  
Liya Zhao ◽  
Zhaoyu Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Energy Harvester ◽  
Degree Of Freedom ◽  
Two Degree Of Freedom

Analysis of broadband characteristics of two degree of freedom bistable piezoelectric energy harvester

2018 ◽  
Vol 5 (8) ◽  
pp. 085704 ◽  
Author(s):  
Dan Zhao ◽  
Minyao Gan ◽  
Chihang Zhang ◽  
Jundong Wei ◽  
Shaogang Liu ◽  
...  
Keyword(s):  
Energy Harvester ◽  
Degree Of Freedom ◽  
Piezoelectric Energy ◽  
Two Degree Of Freedom

Two degree of freedom vibration based electromagnetic energy harvester for bridge health monitoring system

2020 ◽  
pp. 1045389X2095945
Author(s):  
Muhammad Masood Ahmad ◽  
Farid Ullah Khan
Keyword(s):  
Cantilever Beam ◽  
Energy Harvester ◽  
Low Frequency ◽  
Open Circuit ◽  
Electromagnetic Energy ◽  
Degree Of Freedom ◽  
Mode Shapes ◽  
Fixed End ◽  
Two Degree Of Freedom ◽  
Maximum Voltage

This paper presents an electromagnetic energy harvester to extract low frequency and low acceleration vibration energy available in a bridge environment. The developed harvester is a multi-mode oscillator with dual electromagnetic transduction mechanisms. The harvester consists of two cantilever beams. The first cantilever beam is split into two equal pieces along its length and the second beam placed in between them coming back to the fixed end and attached at outer end to the first beam. This way instead of a long conventional cantilever beam a compact harvester is fabricated. Two magnets as proof masses are attached to each free end of the beam making it a two degree of freedom system (2-DOF). The magnets are positioned to oscillate inside hand wound coils during operation. An analytical model was developed and COMSOL multiphysics was used to simulate the mode shapes of the harvester. The mathematical model was simulated for open circuit voltage in MATLAB and showed closely matching results with the experimental values. The harvester is characterized in lab for its performance under sinusoidal vibrations at low frequency (3 Hz–15 Hz) and low acceleration (0.01–0.09 g) levels. The 2-DOF harvester has two resonant frequencies of 4.4 Hz and 5.5 Hz and a volume of 333 cm3. It produces maximum voltage of 0.6 V at first resonance on coil-1 and maximum voltage of 1.2 V on coil-2 at second resonance at 0.09 g. At acceleration of 0.09 g the harvester produced 2.51 mW at first resonant frequency and 10.7 mW at second resonance. Moreover, the AC output voltage of the harvester is rectified to DC voltage by a three-stage Cockcroft-Walton multiplier type circuit. The DC power output at 0.05 g was 0.939 mW at first resonance and 0.956 mW at second resonance while maximum voltages of 5.4 V on coil-1 and 4 V on coil-2 were produced.

A broadband flow energy harvester induced by the wake of a bluff body

2021 ◽  
Author(s):  
Wen-An Jiang ◽  
Xin-dong Ma ◽  
Yong Wang ◽  
Mao Liu ◽  
Li-qun Chen ◽  
...  
Keyword(s):  
Bluff Body ◽  
Permanent Magnets ◽  
Energy Harvester ◽  
Analytical Data ◽  
Degree Of Freedom ◽  
Nonlinear Flow ◽  
Physical Parameters ◽  
Restoring Force ◽  
Flow Energy ◽  
Two Degree Of Freedom

Abstract Wake galloping energy harvesting have been extensively developed to scavenge flow energy from vortex-induced oscillations. Hence, the wake-galloping harvester only has a natural frequency which leads to a very narrow bandwidth. Therefore, it does not operate well under the wide region of shedding frequencies in variable wind speed. To overcome the vital issue, this paper we explored a novel two-degree-of-freedom nonlinear flow energy harvester to collect flow energy induced by the wake of a bluff body. The nonlinear restoring force is realized by using a repulsive magnetic force between two cuboid-shaped permanent magnets, and the electromechanical coupling equations is presented. Based on the method of harmonic balance, the electromechanical governing equations is decoupled, and the first order harmonic solutions are implemented. The modulation equations are established, the amplitude-frequency figures of displacement and voltage are depicted with different detuning parameters. The superiority of the presented energy harvester is contrasted with the single-degree-of-freedom linear and nonlinear cases, the results revealed that the two-degree-of-freedom nonlinear scheme can enhance the bandwidth of flow energy capture. The effect of physical parameters on the scavenged power is discussed. The accuracy and efficiency of the approximate analytical data are examined by numerical simulations.

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