Design And Study Of The Novel Electromagnetic Vibration Energy Harvester

At present, the development trend of wireless sensor network is designing small, long service life and low consumed sensor nodes by using MEMS and micro wireless communication technology. However, compressed size improved the integrity of the structure. Power supply of sensor node can’t be replaced in special occasions. Therefore, how to find a convenient, efficient and safe macro energy storage device to substitute traditional battery becomes a hot topic in recent years. Energy in environment is everywhere, for example solar energy, wind energy, tidal energy, vibration energy and so on. Collect energy from the environment can effectively solve the problem of supplying power for wireless sensor node.According to the characteristics of the actual working environment, combining the electromagnetic induction principle and physical model of electromagnetic energy harvesting device type, the novel electromagnetic vibrating energy harvesting device which is suit to work in low-frequency environment is proposed. By using static and dynamic simulation of Ansoft Maxwell, this paper analyzes the properties of the device. The main works and research results in this paper are as follows:1. The current research of vibration energy harvester exists many problems, for example,the output voltage and energy conversion efficiency is too lower and production process is too complex to realize. Aiming at the problems existing in the research, this paper put forwards two new electromagnetic vibration energy harvesters. One is tubular vibration energy harvester. Its advantages are as follows:(1) This device is designed including closed magnetic circuits which are significant to improve the utilization factor of vibration energy;(2) The symmetrical distribution design of four dentate yokes makes the magnetic flux of the device realizes multiple alternating in the low frequency environment and the induction electromotive force is improved;(3) I-shaped armature helps to reduce magnetic loss in the magnetic circuit and improve the efficiency of energy conversion. Another is magnet fixed vibration energy harvester.This device not only inherits the advantages of the initial structure and tubular vibration energyharvester, but also makes great improvements on the basis of the original:(1) This device add the square shaft which overcomes the stress of oscillator is uneven in complex environment, so that the movement of the vibrator is more stable;(2) Permanent magnet is fixed which improves the environment adaptability and lifetime of the device;(3) The structure is relatively simple and is easy to manufacture.2. By using Ansoft Maxwell, the static infinite element simulations expose the relationship between the maximum coil magnetic flux density and the relative parameter. On the other hand,the date of the dynamic simulations analyzes the influence of the parameter optimization and the turns of coils on the output performance. The dynamic simulation shows that the optimized tubular harvester can produce 1.47 V induction electromotive force which is four times as much than the unoptimized. The linear harvester can supply a maximum effective power at 9.69 mW when the turns of coil is 222.3. Using full-wave bridge rectifier filter circuit device alternates induced current into direct current. The battery supplies power for load by saving the DC to storage battery. The study demonstrates that the new electromagnetic vibration energy harvesting device is able to power for many low consumed power wireless sensor network nodes.