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Energy harvesting from a nonlinear magnet-piezoelectric multi-frequency converter array

In this paper, in order to increase the amount of harvested energy, a vibration-based energy harvester is proposed which is a converter array in a radial arrangement. The converter array consists of four piezoelectric cantilevers including ferromagnetic substrates and a permanent magnet located on a spring in the middle of the converter array. A mathematical model is developed to simulate the electromechanical behavior of the harvester. Differential equations governing the electromechanical behavior of the system are obtained using Lagrange equations. Then the equations solved numerically. The system behavior is investigated in both linear and nonlinear modes and also in the absence and presence of the middle magnet and spring. Two cantilever beams with different thicknesses, with and without tip mass, are used to harvest the energy from the multi-frequencies system. In order to validate the accuracy of the developed model, the results are compared with the results of measured data under white noise excitation. Next, the system is studied under harmonic excitation and the diagrams of output voltage and generated power are plotted. According to the simulated and experimental results, the amount of output voltage from the nonlinear system is at least two times larger than that of the linear system. Moreover, the results indicate that the multi-frequency energy harvesters will increase the bandwidth of the harvesting energy.