Analysis and experiment of an airflow energy harvester based on diamagnetic levitation

Abstract

This paper proposes an energy harvesting structure that can effectively generate electrical power. Diamagnetic levitation mechanism is utilized, with a floating magnet rotor levitated between two pyrolytic graphite plates just using a lifting magnet and airflow. The magnet rotor could be stably suspended under joint action of magnetic forces and diamagnetic forces, being driven to rotate by airflow. Three magnet rotors, with 1.5 mm, 3 mm and 4.5 mm thickness respectively, were adopted in the study so as to investigate the influence of structural parameters of the magnet rotor on the performance of the harvester. Simulation and experiment were carried out for the three magnet rotors. Among the tree magnet rotors, the 1.5 mm-thick one has the best output performance, with the lowest dynamic stability. Therefore, the energy harvester is to find tradeoff between output characteristics and dynamics. In this work, it was discovered that the peak output voltage of the energy harvester increased with the square of flowrate. As the flowrate increased to 3000 sccm, the 1.5 mm-thick rotor was rotating at a speed of 19729 rpm under standard temperature and pressure, with 1.255 V output voltage and 49 mW power. The diamagnetic levitation structure is expected to be applied to sensing, energy harvesting and air bearing under actuation of airflow due to its advantages of low friction, high rotation speed and large levitation space.