Self-powered frequency tuning via energy harvesting

Tuning the resonance frequency of a vibrating system is directly related to its performance in different applications such as energy harvesting and vibration suppression. However, supplying the required energy for tuning is a challenge. This research investigates the idea of using energy harvesting for powering the frequency tuning mechanism. The investigated system is composed of a beam with piezoelectric layers and an external magnetic tuning mechanism, and exposed to harmonic base excitation. In addition, an electrical circuit with a rectifier and capacitor is used to store the harvested energy. The governing magneto-piezo-mechanical equations are derived using the extended Hamilton’s principle, Gauss’s law, and dipole-dipole model. Then, the dimensionless form of the equations is obtained. First, using the harmonic balance method (HBM), the mechanical and electrical responses of the system are approximated. Furthermore, numerical simulations based on numerical integration are used to validate the approximated response. The results show a good agreement between the numerical and HBM results. In addition, frequency and time domain analyses are conducted to study the deflection, charging time, and stored energy. The results show that the harvested energy can be used to power the magnetic frequency tuning mechanism and shift the resonance frequency. Investigating an example energy harvester shows that the application of the self-powered frequency tuning leads to a significant performance enhancement in energy harvesting via a change of 100% in the resonance frequency. Therefore, self-powered frequency tuning confers performance enhancement of oscillators.