Electromagnetic (EM) energy harvester has been proposed in civil engineering for simultaneous vibration mitigation and energy scavenging. One important component governing the performance of harvester is the energy harvesting circuit connected to it. This circuit normally consists of electronic components that are important in regulating voltage and current, storing electrical energy and controlling the mechanical behavior of the harvester. However, these electronic components could be nonlinear in nature. The nonlinearity presented in the circuit could introduce certain nonlinearity to the electromechanically coupled harvester-structure system.

In this study, the vibration mitigation and energy scavenging performance of a structure equipped with an EM energy harvester connected...[ Read more ]

Electromagnetic (EM) energy harvester has been proposed in civil engineering for simultaneous vibration mitigation and energy scavenging. One important component governing the performance of harvester is the energy harvesting circuit connected to it. This circuit normally consists of electronic components that are important in regulating voltage and current, storing electrical energy and controlling the mechanical behavior of the harvester. However, these electronic components could be nonlinear in nature. The nonlinearity presented in the circuit could introduce certain nonlinearity to the electromechanically coupled harvester-structure system.

In this study, the vibration mitigation and energy scavenging performance of a structure equipped with an EM energy harvester connected to a representative energy harvesting circuit are examined. The examined energy harvesting circuit is termed as the standard energy harvesting circuit (SEHC), which is made by a full-wave bridge rectifier connecting a capacitor in parallel with a resistor. The response of this nonlinear coupled system under a harmonic force excitation and a Gaussian white noise force excitation is examined. A first-order harmonic balance method and a statistical linearization method are employed to estimate the steady-state response and the stationary response of the coupled system under the harmonic excitation and the Gaussian white noise excitation, respectively. Numerical simulations and experimental studies are conducted to validate the accuracy of the proposed approximation methods. Results show that both approximation methods can determine the response of coupled system reasonably well.

The effects of circuit nonlinearity are analyzed and discussed. Results show that the damping coefficient of the EM energy harvester becomes loading and structural response dependent due to the circuit nonlinearity caused by the blockage effect of diodes in the full-wave bridge rectifier. To reduce the blockage effect, it is suggested to adopt a bridge rectifier with a small voltage drop and an EM energy harvester with a large electromechanical coupling coefficient. When the blockage effect of diodes is prevented, both vibration mitigation and energy harvesting performance can be enhanced with the increase of short-circuit damping coefficient of the harvester. It is shown that the circuit nonlinearity due to the inclusion of a parallel capacitor in the SEHC is beneficial to the damping capability of the harvester. Results also show that the output power is decreased quite significantly by the circuit nonlinearity. The energy distribution scavenged from a vibrating building is also examined. Results show that the harnessed powers mainly concentrate at the higher stories of a building structure. An optimization framework for maximizing the output power is presented. It is shown that the optimal designs of the EM energy harvester and energy harvesting circuit are affected by the circuit nonlinearity. Overall, it is suggested to consider the circuit nonlinearity in the analysis in order to determine the response of the coupled system accurately. To this end, it is shown that scavenging energy from a vibrating structure is a feasible technology, even though circuit nonlinearity is considered in the analysis.