Design And Research Of Electromagnetic Low-Frequency Vibration Energy Harvesting Devices

Vibration is everywhere in nature. However, energy generated in vibration is always wiped off by dampers or simply ignored. If the energy is harvested and converted to electricity to supply some low-power devices, such as wireless sensor network nodes or EPC system network nodes, which were powered by chemical batteries, it can not only extend the service lives of above-mentioned nodes, but also greatly reduce the environmental pollution caused by chemical batteries. Therefore, vibration energy harvesting devices become a research hotpot concerned by the domestic and foreign scholars.In the paper, two new vibration energy harvesting devices which are adept at working under the condition of low-frequency vibration are designed. These devices are constructed including several closed magnetic circuits, which significantly improve the ability of energy harvesting. Meanwhile, the rack structures in the device lead to the change frequency of the coil magnetic field increasing, so that the device can adapt to work with low frequency vibration. The main work and results of this paper are listed as follows:1. According to the literatures about vibration energy harvesting device, the present research and developing trends of vibration energy harvesting devices are analyzed and made generalizations to find out the reasons for the low efficiency of most existing devices. Then, two new vibration energy harvesting devices including closed magnetic circuits and multi-tooth structures are proposed. The devices are effective enough to work with low frequency vibration due to the closed magnetic circuits and multi-tooth structures constructed in the devices which significantly improve the ability of energy harvesting.2. Combining with the proposed devices’ structures, their working principles are analyzed in detail, and the basic theories involved in the devices are fully elaborated.3. The paper simulates the second device proposed in the paper using finite element analysis software Maxwell. Through the results of Maxwell static simulation of the device in different values of armature height, air gap width and soft magnetic material’s differential permeability, the structure and size of the device are optimized. In the Maxwell transient simulation, unloaded induced electromotive force of the device in1000turns of coils is simulated. With the result, the paper calculates device’s unloaded induced electromotive force and the load’s maximum effective power in different turns of coils. The results show that when works with1Hz vibration, the device can produce unloaded induced electromotive force from0.3V to6.5V, while the load can produce maximum effective power between6.12mW and7.59mW. Thus, the device can be used to supply for some low-power devices.4. Rectifier and filter circuit is presented and analyzed in the paper. The output voltage results in different inductance and filter capacitance values are simulated using Multisim simulation software. And then, the paper introduces the basis of inductance and filter capacitance choice.