Research Of Response Characteristics And Energy Management Of Vibration Energy Harvester

Various electronic products continue to be miniaturized,wireless and portable with the rapid development of integrated circuit technology.And the ultra-low power circuit design technology makes their power consumption lower and lower.Under the effect of scale effect,the conventional battery will exhibit cubic attenuation with the decrease of size,which will result in great challenges to battery life.The power problem has become a bottleneck for the practical use of various micro-systems.Therefore,the new power source is urgently needed to be supplied.The energy harvester can convert energy into electric energy in the environment.The principle is that utilizing photovoltaic,thermoelectric,piezoelectric,electromagnetic and other physical or chemical effects convert the energy of light,heat,mechanical energy and wind energy into usable electrical energy.Vibration energy harvesters can convert vibration energy into electric energy to supply power for the low-power electronic devices.In this paper,we studied the response output characteristics and energy management circuit of the diamagnetic levitation vibration energy harvester.Firstly,the working principle of the harvester was discussed in detail.And the energy harvester structural model was established.Then diamagnetically stabilized magnet levitation principle of the floating magnet was described in detail.Finally,the mechanical analysis was carried out detailed and magnetic force,diamagnetic force,electromagnetic damping force and air resistance force were obtained the theoretical expressions.Secondly,we established two-dimensional nonlinear spring pendulum model to describe the harvester.Utilizing the Newtonian mechanic’s analysis,the two-dimensional motion differential equation of the floating magnet under horizontal excitation condition was determined.Then the COMSOL model was used to simulate and calculate the magnetic force and diamagnetic force in the differential equation.The fitting curve of the magnetic force and diamagnetic force with the displacement was calculated by MATLAB.Then the damping force of the system was solved by the experiment.The mathematical model was solved in MATLAB so that we could get the curve of the rotation angle and the swing length function of the floating magnet.The induced voltage output characteristics were calculated by the Faraday’s law of electromagnetic induction under different external sinusoidal excitation conditions.Finally,the theoretical curves were compared with the experimental results,and the correctness of the model is verified.Thirdly,we established the simulation model to study the energy management circuit of the energy harvester.The sextuple voltage rectification circuit and the booster circuit based on the LTC3108 chip were proposed.In the first circuit,the parameters of each capacitor in the circuit were reasonably optimized.Compared with the voltage doubler circuit,the second circuit was significantly improved,and the output voltage peak could meet the voltage requirements of common micro sensor nodes.Finally,the experimental scheme was developed and the experimental test platform was set up.The output response under constant horizontal excitation peak conditions,the output response under constant horizontal acceleration,the output response characteristics under sweep conditions,and the human body motion excitation conditions were determined by experiments.The experimental data was used to study the response output characteristics of the harvester under different excitation conditions.The optimal working environment and optimal working conditions of the collector were explored.The experiment results shows that the energy collector can light the LED and it is potential to power the portable electronics.