| The development of the new generation of information technology based on the Internet of Things has become an important starting point to promote industrial upgrading.The intelligent information age of the Internet of Everything relies heavily on the underlying data of the physical world provided by sensor nodes,which directly determines the deployment of massive sensor nodes in the future.At present,how to power such a large number of sensor nodes and mobile devices has become the core problem hindering the further development of the new generation of information technology.There is an obvious contradiction between energy demand and energy supply at present: power demand presents the characteristics of distribution,diversification,low power,wireless connection and so on.The current grid power supply system is inflexible in terms of layout,whereas opting for battery power supply can result in additional expenses for maintenance and contribute to environmental degradation.Therefore,providing effective and multiple sensor energy supply according to local conditions is an important basis for the future development of the era of information intelligence.One possible solution is to develop micro and nano energy technologies to convert widespread environmental energy into electricity and achieve personalized energy supply at iot nodes.Energy acquisition and storage based on light energy,heat energy,mechanical energy and electromagnetic energy have been the focus of research in recent years.The triboelectric nanogenerator(TENG)based on triboelectric and electrostatic induction principles and its related composite nanogenerators have become a reliable source of distributed and sustainable energy for sensor nodes due to their unique advantages in structure,deployment and efficiency.In the face of the above problems,a composite nanogenerator is designed in this paper,and the coupling enhancement between generators with different mechanisms,power management of the composite generator and its application are explored.The details are as follows:(1)A triboelectric-electromagnetic composite nanogenerator with columnar structure is designed,which can conveniently change the force unit to realize the function switch between water wave energy capture and wind energy capture.By integrating with the energy management circuit,the obtained energy can directly drive the hygrograph operation and data wireless transmission without an additional power supply.The clever mechanical structure design combines circular motion with contact separation mode generator to achieve 16 times mechanical frequency increase,effectively improving the conversion efficiency of mechanical energy while reducing mechanical loss.The TENG can generate an open-circuit voltage of about 200 V and a short-circuit current of 14 μA under a low frequency excitation of about 1.1 Hz.An electromagnetic generator(EMG)can produce an open circuit voltage of 1.5 V and a short circuit current of 8 m A.Detailed analysis of the electrical signal shows that the coupling of the two makes the output voltage of EMG significantly increase.A further analysis of the dynamic and electrical processes was carried out using a high speed camera to reveal the coupling enhancement behavior between the two.The problems mentioned above are verified by FFT analysis of electric signal.The quantitative analysis results show that the coupling of the two methods increases the output of EMG by 1.26 times,and the overall increase by 214%.Based on the detailed analysis of their external electrical characteristics,the power management circuit adapted to the compound generator is designed and realized.The Buck circuit is realized by the thyristor based electronic switch design,which reduces the TENG impedance.The EMG units are connected in star shape and connected to the output end of the Buck circuit after the polyphase rectifier circuit.The overall output capacity of the EMG is verified by testing the charging speed and carrying capacity of the capacitor.This work achieves efficient capture of low frequency mechanical energy,and the output stable DC voltage can be used by electronic systems.It has an important reference value for the construction of commercial low-power sensor nodes.(2)There are various forms of renewable energy in nature,and the single mechanical energy collection power output is limited,which limits the overall electrical output capacity and application scenarios of micro-nano energy systems.The multi-source complex generator can solve the above problems to a certain extent by collecting multiple environmental energies.In the second work,we design a multi-source composite energy harvesting device by organically combining three kinds of energy harvesting devices in different forms and mechanisms,namely solar cell,EMG and TENG.Based on the analysis of the electrical output performance of the three energy collection units with different mechanisms,the design of the power management circuit is preliminarily optimized to bridge the performance limitations caused by the impedance and voltage differences and improve their mutual matching: The solar input uses the Boost circuit to increase its electrical output,the electromagnetic power generation through the transformer to increase the output voltage,and the triboelectric power generation through the Buck circuit to reduce the impedance and stabilize the output.The organic combination of the three improves the overall energy utilization rate,realizes the power supply application of a variety of different low-power components,and expands its application scenarios.The analysis and design method of this work has a certain reference value for the development of multi-source energy harvesting technology,and explores an effective method for the engineering application of micro-nano energy system. |
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