Research on a Piezoelectric Energy Harvester with Rotating Magnetic Excitation

This paper presents a piezoelectric energy harvester with rotational magnetic excitation. Through the rotation of the rotating body, the intermittent magnetic force between the driving magnet and the tip magnetic mass drives the piezoelectric element to vibrate nonlinearly to generate electrical energy. The working principle and vibration model of the proposed energy harvester are studied theoretically and experimentally. With two driving magnets, 5-g tip magnetic mass, and 8-mm radial excitation distances, the piezoelectric energy harvester captures energy efficiently. The results demonstrate that the piezoelectric energy harvester produces three resonance frequencies of 5 Hz, 8 Hz, and 10 Hz. When the rotation frequency is 8 Hz, the maximum open-circuit voltages of the primary and auxiliary piezoelectric beam is 63.24 V and 30.38 V, respectively. The primary and auxiliary piezoelectric beam gets the maximum average power with external resistance is 125 KΩ and 75 KΩ, respectively. The maximum average power of the primary and auxiliary piezoelectric beam is 12.24 mW and 3.92 mW, respectively. At the maximum power of the primary and auxiliary piezoelectric beam, the voltage across the resistance is 39.12 V and 17.12 V, respectively.