A magnetically excited broadband rotary piezoelectric energy harvester with nonlinear energy sink: Theoretical investigations and experimental Verifications

Energy harvesting technology based on smart piezoelectric materials still faces the challenge of expanding bandwidth and increasing frequency bands of harvesters. In response to this challenge, a magnetically excited piezoelectric harvester with nonlinear energy sink is proposed. This work establishes a nonlinear magnetic force model for the magnetic rotor and auxiliary magnets. The electromechanical coupling equations for the harvesting system are formulated based on Newton's and Kirchhoff's laws, and their applicability is verified by experiments. The numerical calculation method is employed to analyze the effects of the magnetic rotor types and the main position parameters of the auxiliary magnets on the performances. The analysis results show that a single piezoelectric oscillator can have multiple working frequency bands due to the special form of the force exerted by the alternating magnetic excitation; the nonlinear energy sink enhances the oscillation deflection at low speeds; the position parameters of the auxiliary magnets can adjust the band width between the power peaks and improve the power. In the laboratory tests, the harvester lit up 67 LEDs and power for a Bluetooth temperature and humidity sensor at 170 rpm. The mobile terminal received the monitoring data transmitted by the sensor, realizing the self-powering function of wireless sensors.