Wide Frequency Range Vibration Energy Harvester Based on Asymmetric Springs
Gao Kai1, Peng Han2, Wang Shaojing1, Xu Peng1, Chen Yong2, Chen Jiahua2, Sun Hanyi2
1. State Grid Shanghai Electric Power Research Institute Shanghai 200437 China; 2. State Key Lab of Advanced Electromagnetic Engineering Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China
Abstract：With the rapid development of the Internet of Things, more and more wireless sensor networks and low-power electronic devices have been widely used. At present, the main power source of these devices is still traditional chemical batteries. These batteries have low energy density, short lifespan, and environmentpollution. Moreover, replacing batteries for hundreds of millions of sensors requires a lot of manpower and material resources. Therefore, obtaining energy from environmental energy such as the sun, heat, wind, vibration, etc. as an alternative energy source for these devices has attracted considerable research interest. Among these energy sources, the vibration energy in the environment is widely regarded as one of the most concerned and researched energy sources because of its existence and not restricted by the environment. However, vibrations in the environment usually have wide frequency characteristics. In order to effectively harvest energy from these vibration sources, a wide frequency range energy harvester is required. In this paper, a novel wide frequency range vibration energy harvester based on asymmetric springs is proposed. A new architecture of dual-asymmetric-springs with one magnet is discussed for wide frequency range coverage, flexible vibration pattern and easy to implement. Firstly, the basic theory of electromagnetic power generation is introduced, and physical characteristics of planar spring with bended beams are investigated. The characteristic frequencies at different spring designs are presented which helps for future design adjustment. It is concluded that the thicker the spring thickness is, the higher characteristic frequency will be. The more spring beams are, the higher characteristic frequency will be. The longer spring beams is, the higher characteristic frequency will be. Secondly, the architecture of vibration energy harvester with asymmetric springs is explored. Vibration movement feature and electromagnetic conversion features are fully discussed with Finite-element analysis. The proposed architecture has three different vibration patterns which can be adopted to different vibration environments. The time domain vibration movements is also shown. It is concluded with asymmetric springs, two peak movement amplitudes appear at different frequencies. For the same spring, the amplitude at lower characteristic frequency is higher than the amplitude at higher characteristic frequency. The lower characteristic frequency is, the steeper the amplitude will be. The thicker the spring is, the two characteristic frequencies are more apart from each other. Finally, the prototype of the proposed vibration energy harvester based on asymmetric springs is designed and fabricated. Magnetic of N38 is selected. The outer case and asymmetric springs are fabricated through 3D print. The overall size of the prototype is 62 mm×32 mm×17 mm, with the diameter of single spring of 25 mm, size of magnet of 40 mm×20 mm×5 mm, height of the coil at one side of 3 mm. The prototype is tested using vibration testing platform in the lab. When the thickness of the springs is 0.6 mm and one is two-beams and one is three-beams, the harvested voltage reach two peak value of 529.1 mV and 229.7 mV at characteristic frequency of 34 Hz and 61 Hz respectively. When the thickness of the springs is adjusted to 1mm and one is two-beams and one is three-beams, the harvested voltage reach two peak value of 632.6 mV and 244.9 mV at characteristic frequency of 67 Hz and 115 Hz respectively. The peak harvested power of the proposed vibration energy harvester based on asymmetric springs reaches to 200 μW.
高凯, 彭晗, 王劭菁, 徐鹏, 陈永, 陈佳桦, 孙寒燚. 基于非对称弹簧的宽频率范围振动能量收集器[J]. 电工技术学报, 0, (): 5-5.
Gao Kai, Peng Han, Wang Shaojing, Xu Peng, Chen Yong, Chen Jiahua, Sun Hanyi. Wide Frequency Range Vibration Energy Harvester Based on Asymmetric Springs. Transactions of China Electrotechnical Society, 0, (): 5-5.
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