| According to the distributed energy entropy theory,stepping to the era of Internet of Things(Io Ts),large-scale centralized power plants may not be able to meet all the power demands of distributed sensors because of the complexity of wiring,environmental pollution,and waste of resources.Therefore,it will be an ideal scheme to harvest mechanical energy from the ambient environment and power the sensors by triboelectric nanogenerator.The regenerative braking system can effectively convert the excess kinetic energy in the braking process into electrical energy.Most of the existing regenerative braking systems are generators based on electromagnetic induction.Researchers pointed out that under the low-frequency and micro-amplitude mechanical input,compared with electromagnetic generators,the triboelectric nanogenerator can generate electricity with higher efficiency.Thus,it would be an ideal solution to introduce triboelectric nanogenerators into the system for harvesting braking kinetic energy at low frequency.However,it is noteworthy that due to the characteristic of intrinsic high voltage,low current,and high internal impedance,triboelectric nanogenerator generates impedance mismatch and low energy conversion efficiency while powering the traditional electronic devices.Therefore,it is urgent to develop an efficient triboelectric power management circuit to break through the bottleneck of the practical application.In order to expand the application of triboelectric nanogenerators in regenerative braking systems and explore novel and efficient energy management circuits,this thesis mainly focuses on the two main issues of braking energy recovery device and energy management circuits.The contents and achievements are as follows:(1)The output performance of the freestanding triboelectric-layer-based nanogenerator was analyzed by simulation and experiment.The dependance of speed and contact state on open-circuit voltage,short-circuit transferred charge density and output power were explored.(2)A set of series mechanism was designed and installed on the bicycle disc brake for kinetic energy recovery in the actual braking scene.The electrical output and anti-fatigue characteristics of the brake-generator were measured experimentally,and an electronic speedometer was driven for real-time speed monitoring.(3)A novel power management idea of the triboelectric nanogenerator and the switch of the three-terminal cantilever beam structure are proposed.The quantitative relationship between the driving voltage and the structural parameters is determined through theoretical derivation and experimental exploration.(4)A switch management circuit with resistive load was built,and the energy efficiency and power improvement of switch management under resistive load were characterized by the voltage-charge curve.The energy extraction efficiency is 76.01%,which is up to 113.3 times higher than ordinary circuits.(5)A switch management circuit with capacitive load is built,and the average energy storage power is increased by 47.5 times under a capacitive load of 4.5m F.The average power of the energy storage circuit for powering the resistor reaches a peak value of 116.06 μW around 470 kΩ,which is 1.554 times higher than the maximum AC power under optimal resistance.This work shows the feasibility of TENG’s potential application on power deceleration systems,which can establish a powerful energy supply for sensor network of intelligent transportation system in the future. |
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