Equivalent Circuit Analysis of a Nonlinear Vortex-Induced Vibration Piezoelectric Energy Harvester Using Synchronized Switch Technique

Introducing nonlinearity into vortex-induced vibration (VIV) piezoelectric energy harvesters (PEHs) can enlarge bandwidths and improve energy harvesting efficiency. Through the analogy between mechanical and electrical domains, the mechanical model of the PEH can be equivalently represented by a circuit model, and the influences of the interface circuits on the energy harvester effect can be studied more conveniently. In this article, a magnetically coupled nonlinear VIVPEH prototype is first developed and tested in the wind tunnel. Second, the equivalent circuit model is established to study the performance of nonlinear VIVPEH. The simulation results are compared with the experimental ones for verification. Finally, the nonlinear VIVPEH is shunted to a simple ac circuit, a standard dc circuit, and SSHI interface circuits to investigate the effects of different interface circuits. The results show that the bistable nonlinear structure can increase the working bandwidth of the VIVPEH, indicating at least an 114.3% improvement over the monostable one. The P-SSHI circuit interface can effectively increase the average power output of the VIVPEH by 65.04% and 174.32% compared to the ac and dc circuits. The work in this article provides valuable insights and guidelines for designing efficient nonlinear VIVPEHs using magnetic coupling and advanced interface circuits.