A novel bidirectional non-contact plucking rotary energy harvester with an orthogonal piezoelectric oscillator: Design and experimental investigation

One key challenge of the energy harvesting technology lies in how to fully utilize external environmental excitation to collect ambient energy and convert it into electrical energy efficiently. To address this challenge, this work proposed a bidirectional non-contact plucking rotary piezoelectric energy harvester, based on the spatial distribution characteristics of magnetism. This work was initiated by establishing a mathematical model for the rotating magnetic field and calculating the magnitude of the magnetic forces. Numerical findings indicated that the quantity of rotating magnets had an impact on the magnitude and distribution of these magnetic forces. Leveraging the distinctive attributes of the rotating magnetic forces, this work introduced an orthogonal piezo-oscillator, designed to concurrently respond to magnetic forces along two orthogonal directions. Subsequently, this work conducted experimental research on the piezoelectric oscillators. The experimental results indicated that the number of magnets affects the power output bandwidth and position of the effective frequency. A mathematical relationship exists between the resonant frequency, the number of magnets, and the natural frequency. The results demonstrate that the total peak output power of the harvester could reach 3.29mW calculated by RMS voltage at 301 rpm, and the charging rate could reach 0.39 V/s at 300 rpm.