Study on Characteristics of Magnetostrictive Bistable Energy Harvester with Spring Oscillator

Monostable cantilever beam magnetostrictive energy harvester needs to operate at a specific intrinsic frequency, while the conventional magnetostrictive bistable energy harvester (CMBEH) with the introduction of a magnetic force has difficulty in forming the inter-trapping motion under weak excitation, which results in a narrow operating bandwidth. In order to broaden the operating bandwidth of the harvester and improve its output power, a magnetostrictive bistable energy harvester with an auxiliary spring oscillator (MBEH-SO) is proposed. Firstly, a coupled machine-magneto-electric model of MBEH-SO is established based on the intrinsic equations of magnetostrictive materials, Faraday's law of electromagnetic induction and the magnetic dipole model, and then the potential morphology, frequency scans and amplitude scans of the harvester are analyzed in detail numerically using this model, and the results show that the MBEH-SO possesses complex dynamic phenomena such as chaos, inter-trapping and intratrapolating motions. Compared with the conventional magnetostrictive bistable energy harvester, its effective bandwidth is increased by at least four times, the maximum average power generated can be up to 41.2 mW, and the excitation amplitude required to trigger the inter-trap motion can be reduced by up to 50%. Numerical simulation results show that the motion of the spring oscillator can provide additional kinetic energy for the cantilever beam to facilitate the escape of the potential trap, and its resonance effect can easily lead to the stable operation of the cantilever beam in a high-energy orbit, thus generating an independent operating bandwidth. MBEH-SO has the excellent performances of wide bandwidth, high power, and low threshold, which is conducive to the harvesting of energy from the low-frequency and weakly-excited environmental vibration.