A Hybrid Piezoelectric-electromagnetic Power Generation Technology And The Experimental Study

With the rapid development of MEMS, SoC(System on a Chip), wirelesscommunication technology and computer technology, wireless sensor networktechnology has become a research hotspot. At present, the vast majority of wirelesssensor nodes are battery-powered. However, the traditional chemical batteries havemany shortcomings, such as limited life span, requirement of periodical replacement,environmental pollution etc. To realize the full potential of wireless sensors, it requiresself-sustainable power source. Vibration energy harvesting technique provides apromising solution in this regard. The most commonly pursued energy harvestingmechanisms are electrostatic, electromagnetic, and piezoelectric. Among them,piezoelectric energy harvester has been paid more attention because of its large energydensity, ease of miniaturization, non-electromagnetic. In order to improve the poweroutput two independent energy harvesting techniques can be coupled to provide higherelectrical damping. And in this work, a hybrid piezoelectric-electromagnetic powergeneration technology is studied. A theoretical power output model is presented andverified by the Finite Element Simulation method and the experimental method.Firstly, according to theory of vibration, mechanics of materials, piezoelectrictheory and electromagnetic theory, a mathematical model of a hybrid power generatorwas established to evaluate the power output. Based on the mathematical model, theoptimization of the power generator was conducted. The numerical results show that thetotal power output of the hybrid device can be increased by optimizing the external load.and the maximum power is obtained when the sum of piezoelectric damping and theelectromagnetic damping match with the mechanical damping.The power output is analyzed by using the finite element software. ANSYS is usedto analyze the power generating performance of stand-alone piezoelectric energyharvesting technique. Ansoft Maxwell2D/3D is used to evaluate the power output ofthe stand-alone electromagnetic energy harvesting unit, respectively. Sequentialcoupling method is used to analyze the hybrid piezoelectric and electromagnetic energyharvesting technique.Finally, a prototype of the hybrid piezoelectric-electromagnetic power generatorwas manufactured. An energy collection circuit was made. Then the power generatingperformance of the hybrid device was tested. The experimental results agree with thoseof the theoretical analysis and finite element simulation very well. It shows that thereexists a coupling effect between the two different mechanisms. The study also provesthat even though the power output from both of the two mechanisms of the hybriddevice has declined, compared with the un-coupled stand-alone power generation technique, respectively, a increase in the total power output can be obtained by adjustingparameters such as external load resistance.