Development and performance evaluation of a wheel-type cantilevered piezoelectric rotational energy harvester via an unfixed exciting magnet

A wheel-type cantilevered piezoelectric rotational energy harvester (wheel-type PREH) via an unfixed exciting magnet was presented to harvest energy from rotational motion without or far away from a fixed support. To verify the structural feasibility and figure out the effect of rolling exciting magnet and excited magnet on the dynamic characteristics and power generation performance of the wheel-type PREH, the theoretical analysis, simulation, fabrication and experimental testing were performed. The results showed that the performance of the wheel-type PREH depended on the rotary speeds, proof mass and piezo-cantilever mass, number of exciting magnets, cylindrical sleeve materials and so on. When other parameters were constant, there were multiple optimal rotary speeds for the maximal amplitude-ratio, output voltage, electrical energy and output power to achieve peak. Besides, the total number of voltage crests per second did not change with rotary speed. There was a constant optimal resistance load for the wheel-type PREH at different rotary speeds to achieve maximal power. The PREH prototype could yield a maximum output power of 0.74 mW at 767 r/min with optimal load resistance of 215 kΩ and 40 different color LEDs in parallel and a low power light strip could be lighted by wheel-type PREH.