Parameter optimization of magnetostrictive bistable vibration harvester with displacement amplifier

The vibration harvester can transform the ambient vibration energy into electrical energy for the use of microelectronic equipment. Currently, the introduction of bistable structure in magnetostrictive harvester makes the system have two equilibrium states, thus the output capacity of the system is improved. In order to further improve the working ability and its ability to harvest vibration of magnetostrictive bistable harvester with displacement amplification mechanism, the identification of the key parameters of the magnetostrictive bistable vibration harvester's mathematical model are first proposed in the paper. The accurate values of system damping, electromechanical coupling factor, piezomagnetic coefficient and permeability are obtained. On this basis, bistable structure and displacement amplification mechanism in the harvester are optimized, including the repulsive permanent magnets distance in the bistable structure, mass ratio and stiffness ratio between the bistable structure and the displacement amplification mechanism. Finally, the working ability of the optimized prototype is tested through experiments. The results show that the output voltage and electrical power of the optimized prototype are increased by 2∼4 times and 4∼15 times compared with the unoptimized prototype. Under the excitation amplitude of 7.84 m/s2, the voltage of the optimized prototype reaches 2.96 V, and the electrical power reaches146.032 mW.