Improvement of force factor of magnetostrictive vibration power generator for high efficiency
Improvement of force factor of magnetostrictive vibration power generator for high efficiency
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DOI：
10.1063/1.4907237
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发表时间：
2015-05-07
影响因子：
3.2
通讯作者：
Yamada, Sotoshi
中科院分区：
文献类型：
--
作者：
Kita, Shota;Ueno, Toshiyuki;Yamada, Sotoshi
我们开发了用于无电池无线电子产品的高功率磁致伸缩振动发电机。发电机是基于一个悬臂的平行梁结构，由线圈缠绕的Galfenol和带有永磁体的不锈钢板组成。施加在尖端的振荡力使悬臂梁在振动中发生弯曲，从而使Galfenol板产生应力变化，从而引起磁通变化，根据感应定律在线圈上产生电压。这种发电机比传统的，如压电或移动磁铁类型的优点，在高效率，高鲁棒性和低电阻抗的点。我们关注的是能量转换效率随尺寸的提高。特别是力因子，即振动中电动势（电压）对叶尖速度的转换比，在能量转换过程中具有重要作用。首先建立了力因子的理论值，然后通过实验验证了力因子的有效性，采用7.0 x 1.5 x 50 mm的Galfenol梁和1606匝绕制线圈对四种原型进行了尺寸参数的比较。此外，还测量了原型的能量转换效率随负载阻力的变化。在外力为25 n的情况下，在202 Hz的自由振动频率下，能量转换效率最高，瞬时功率为0.73 W，能量为4.7 mJ。此外，还发现能量转换效率不仅与力因子有关，还与振动的阻尼（机械损失）有关。(C) 2015 AIP出版有限责任公司
We develop high power magnetostrictive vibration power generator for battery-free wireless electronics. The generator is based on a cantilever of parallel beam structure consisting of coil-wound Galfenol and stainless plates with permanent magnet for bias. Oscillating force exerted on the tip bends the cantilever in vibration yields stress variation of Galfenol plate, which causes flux variation and generates voltage on coil due to the law of induction. This generator has advantages over conventional, such as piezoelectric or moving magnet types, in the point of high efficiency, highly robust, and low electrical impedance. Our concern is the improvement of energy conversion efficiency dependent on the dimension. Especially, force factor, the conversion ratio of the electromotive force (voltage) on the tip velocity in vibration, has an important role in energy conversion process. First, the theoretical value of the force factor is formulated and then the validity was verified by experiments, where we compare four types of prototype with parameters of the dimension using 7.0 x 1.5 x 50 mm beams of Galfenol with 1606-turn wound coil. In addition, the energy conversion efficiency of the prototypes depending on load resistance was measured. The most efficient prototype exhibits the maximum instantaneous power of 0.73 W and energy of 4.7 mJ at a free vibration of frequency of 202 Hz in the case of applied force is 25 N. Further, it was found that energy conversion efficiency depends not only on the force factor but also on the damping (mechanical loss) of the vibration. (C) 2015 AIP Publishing LLC.