On the dynamics of a novel energy harvester to convert the energy of the magnetic noise into electrical power

Magnetic and mechanical noise in the frequency range of MHz are available in the environment and could be harvested for human convenience. This manuscript focuses on the dynamical behavior of hybrid magneto-mechano-electric (MME) energy harvesters to convert the energy of the magnetic noise and mechanical noise to electrical power using a composite energy scavenging structure. The proposed apparatus is composed of a piezoelectric (PZT-5A) layered beam on which a magnetostrictive material (Metglas-2605SC) is deposited. Once the device is exposed to external magnetic noise, Metglas-2605SC undergoes mechanical strain, and as a result, the mechanical strain is converted to electrical potential difference throughout the PZT-5A layer. In the present manuscript, the energy harvesting device is modeled as a cantilever beam, and the equations of motion are derived using Newton's second law. The governing equations of motion, along with the output electrical potential difference equation are then discretized and numerically integrated over time, the frequency response curves for deflection, harvested power, and voltage are determined, and the effect of governing parameters on the output power is investigated. It is concluded that in the absence of mechanical damping, the response resembles that of a damped mass-spring oscillator confirming the energy consumption throughout the output circuit. In addition, as the external load resistance increases up to a particular value (164k Omega), the attenuation rate of the response amplitude, and accordingly, the harvested power also increases. Beyond that particular value, the collected energy decreases by further increasing the load resistance. The results revealed that between two successive natural frequencies, there exists an anti-resonance region, where the response amplitude dramatically drops, and the operating area of the energy harvester needs to be kept well away from this zone in the frequency domain. The analytical results are verified by presenting a finite element simulation of the cantilever energy harvesting model, in which the distribution of stress and harvested voltage are determined. (C) 2020 Elsevier Ltd. All rights reserved.