Enhanced the capability of magnetostrictive ambient vibration harvester through structural configuration, pre-magnetization condition and elastic magnifier

Vibration energy harvesting, which converts the mechanical vibrations that are commonly available in the surrounding environment to electrical energy, can realize self-power sensing, control and actuation, with the advantages of convenience, energy saving, eco friendliness and sustainability. However, it has some weakness, such as low output power, low efficiency, poor environmental adaptability and low reliability, which restrict its practical applications. It is necessary to optimize the harvester's structure, bias conditions and so on to adapt to the characteristics of ambient vibration, and then enhance the mechanical energy harvesting capability. This paper focuses on improving capability of the cantilever magnetostrictive harvester which is a new technology and still in the stage of proof-of working mechanism and concept prototype design. It systematically clarified the qualitative laws of the major factors affecting harvesting performance, including geometry, bias conditions, etc. Moreover, considering the low frequency characteristics of ambient vibration, it proposed an elastic magnifier with additional mass which can simultaneously enhance vibration harvesting, reduce resonance frequency and broaden effective frequency range. It was experimentally verified that the optimized magnetostrictive harvester can convert the mechanical vibration of 1 g acceleration into the voltage of 1210 mV. It was able to output 11 mW power to a load and the normalized power density reached to 18.3 mW/cm³/g. The magnetostrictive harvesting prototype successfully powered for multiple light emitting diode lamps, multiple digital display tubes and a low power electronic meter.