A Novel Equivalent Circuit Model of the Double-Beam Magnetically Coupled Piezoelectric Energy Harvester

In this paper, a new equivalent circuit model based on the double-beam magnetically coupled piezoelectric energy harvester (DMPH) is proposed. The comparison between the DMPH and uncoupled double-beam array piezoelectric energy harvester (UCPH) confirms that the magnetic coupling broadens the working frequency range of the DMPH and complicates its electrical response, which poses challenges to the establishment of the equivalent circuit model (ECM). Therefore, the magnetic dual-circuit coupled equivalent circuit model (MECM) is established based on the conventional ECM, where the nonlinear capacitor module is used to represent the magnetic force. The output voltage waveform and average power of the DMPH are measured and compared with the simulation results of both MECM and ECM. The results confirmed that the accuracy of the MECM is significantly better than that of the ECM. Based on this, the average power of the MECM and DMPH under three motion states is compared, demonstrating a determination coefficient exceeding 0.904 between the simulation and experimental results. The results of three comparative experiments validate the accuracy of the proposed MECM in simulating the electrical responses of the DMPH.