A Hybrid Beam Structure Piezoelectric-electromagnetic Power Generation Technology

Because of the small size, the low power consumption, the wide potentialapplication and the ability to be employed in inaccessible and hostile environments,wireless sensors have a promising application prospects. Traditional power storagessuch as batteries have a limited lifetime, must be maintained (e.g. recharged or replaced)periodically, bring the material waste, environmental pollution and other issues.Therefore Wireless sensors need a method to provide energy for themselves. The energyharvesting from ambient vibration sources is a smart solution and has beencomparatively immense researched over the last decade because of its promising energydensity and ease of acquisition. Piezoelectric and electromagnetic are the most effectiveway of turning mechanical vibrations into electrical energy. Many researchers havedone a lot of work (research of structural, circuit optimization, etc). In order to enhancethe energy conversion efficiency, some of them proposed a kind of hybrid energyharvesting technology coupling piezoelectric and electromagnetic mechanisms together.The hybrid energy harvester owns the advantage of being clean, stable, has a higherenergy density and a wider frequency band.In this paper, a new hybrid energy harvester will be presented which can not onlyincrease the output, but also greatly broaden the frequency bandwidth. This paperconducts the following works:Firstly, By using the theories of nonlinear oscillators and piezoelectric equation,the mathematical model of the single electromagnetic and piezoelectric energy harvesterwill be established to evaluate the power output. The total power output of the hybridpower generator will be obtained after adding the coupled output of the piezoelectricand electromagnetic systems. The numerical results show that the piezoelectric-electromagnetic vibration energy harvester has3times the bandwidth in comparison tothe corresponding stand-alone, single harvesting mode devices.Secondly, the corresponding simulation finite element is performed. The model ofthe electromagnetic system was established using MAXWELL, and the model of thepiezoelectric system was established in ANSYS. External loads and structuralparameters were optimized to maximize the power output of the hybrid energy harvester.The results show that external loads and structural parameters have great influence onthe power output of the harvester.Finally, According to the CAD design，a prototype of the hybrid power generatorwas manufactured. Then the power output performance of the hybrid device was tested.The experimental results show that the peak power outputs of the hybridharvester are7.2mW and16.4mW at the resonance frequencies of8.5Hz and16Hz.And this hybrid harvester broadens the frequency bandwidth effectively. The averageerrors of the power output and peak frequency of numerical analysis and finite elementsimulation to experimental results are acceptable.