Study of a magnetostrictive energy harvester for harvesting transient shock vibration

In recent years, vibration energy harvesting technology from environmental vibration has been a research topic of increasing interest. It is a new way to overcome the problem of power supply for low-power electronic devices. To utilize the low-frequency random vibrations in the environment, we designed a magnetostrictive (Fe-Ga alloy) energy harvester for transient shock vibration, which effectively converts low-frequency shock vibration into high-frequency vibration. Based on the mechanical dynamics analysis of the Fe-Ga alloy cantilever beam, we established the energy harvesting model of the machine-magneto-electric coupling system. The influence of the pre-magnetized magnetic field on the energy harvesting device was analyzed using finite elements and experiments were conducted under various magnetic field arrangements. Experimental testing was conducted to investigate the main working performance of the harvester in depth under transient excitation. The effect of applied load resistance on generation power, generation power density, as well as mechanical and electrical energy conversion efficiencies was investigated. It was experimentally verified that the magnetostrictive energy harvester could reach a voltage of 1356 mV, power of 26.163 mW, and power density of 115.01 mW/cm3 under the excitation of 2 N. When connected in series with a 17 Ω resistor, the average efficiency of mechanical energy conversion to electrical energy was about 30.52%. With the assistance of a signal interface circuit, the energy harvester successfully lit up the LED display of an electronic meter, verifying the power generation ability of the harvester. The results of the study effectively utilize the transient shock vibration in the environment, and provide an effective and feasible method for the practical application of magnetostrictive harvesters.