A rotating piezoelectric energy harvester in a spindle shaft under magnetic repulsive-attractive forces

The utilisation of rotational motion in a piezoelectric energy harvester is believed to have significant potential for generating sufficient electrical energy to sustain self-powered wireless sensor systems. The system needs dynamic and rotating components, which means it must adapt to the environment and be integrated into the rotating shaft. Therefore, this study proposed a novel solution to effectively tackle these issues using the rotating piezoelectric energy harvester (RPEH). This was based on the magnetic repulsive and attractive forces produced by coupling stationary and rotating magnets on the piezoelectric surface. The magnets were arranged symmetrically on opposite sides to serve as the source of excitation. Moreover, the voltage and power generation capacity of the harvester were investigated when the system was subjected to different excitations of spindle shaft speed. The results showed that the system attained a maximum instantaneous output voltage of 8.1 V at a rotating speed of 1200 revolutions per minute (rpm), and this enabled the charging of a capacitor with a power level of 2.4 mW at a load of 10 kΩ. This showed that the proposed harvester had a significant level of durability and possessed considerable potential to supply power to wireless sensors.