电磁式两自由度高效振动能量采集技术研究

Research on two-degree-of-freedom electromagnetic high-efficiency vibration energy acquisition technology

振动能量广泛存在,将其收集起来可以为用电设备供电。为提高振动能量的采集效率,本文提出一种新型振动能量采集装置,利用弹簧和单摆的两自由度模型,可将外界的单向振动转换为摆的摆动,避免由往复式直线运动惯性而造成的机械能损失,其中摆上嵌入永磁体作为动子。基于拉格朗日方程建立该装置的两自由度振动模型,再根据摆的角度和电磁感应定律建立输出电动势模型,其中磁场利用有限元法计算。基于模型的仿真结果表明,在幅值20 mm、频率10 Hz的正弦振动激励下小车的水平位移放大了3倍,动子最大摆动角度接近80°。将该装置在振动台上进行测试,输入激励为斯柯达轿车的市区公路振动加速度谱,测得的电动势平均有效值为8.47 V,其平均输出功率约为594 mW,可满足手机等电子设备的供电需求。

It is meaningful to collect vibration energy which is widespread for powering electrical equipment.A novel two-degree-of-freedom vibration harvester is presented to improve the energy harvesting efficiency.The external one-way vibration excitation can be converted into a pendulum swing.Therefore,it can avoid the loss of mechanical energy caused by the inertia of the reciprocating linear motion.Here,magnets are embedded in the pendulum as a mover.The harvester can be modeled as a two-degree-of-freedom mechanical system on the basis of Lagrange Theorem.The output electromotive force(EMF) can be calculated by Faraday Law and the angular displacement of the pendulum.And the magnetic field is solved by finite element method.The simulation results under sinusoidal excitation with amplitude of 20 mm and frequency of 10 Hz indicate that the horizontal vibration displacement of the cart is amplified by 3 times and the maximum swing angle of the mover is close to 80°.A prototype is fabricated accordingly,and is tested on the vibration generator.The input excitation is the vibration acceleration spectrum of the urban road of the Skoda car.The test result is that the effective value of EMF is 8.47 V,and the average output power is 594 mW.And it can meet the power needs of mobile phones and other electronic devices.