Development of a 2-DOF WEH Based on Biaxial Hula-Hoop Motion

• Main Authors: Chih-Kuang Lee, 李治廣
• Other Authors: Yu-Jen Wang
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/7bz2s7

碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 106 === Buoys equipped with sensors and wireless transmitters can monitor ocean conditions However, powering these sensors and transmitters is using batteries is unavailable for power replacement. Therefore, this study develops a two-degrees-of-freedom (2-DOF) wave energy harvester (WEH) for pitching and rolling motion, composed of an eccentric gyro ring, four circular Halbach-array magnetic disks and four stator-mounted iron cores, to harvest wave energy from a floating buoy considering pitching, rolling and heaving motion. The eccentric gyro ring enhances power generation by revolving in a biaxial hula-hoop motion rather than a reciprocating motion because of higher angular velocity. The dynamic equations of the eccentric gyro ring mounted on the buoy were derived using the Lagrange-Euler method, and the motions of the buoy were measured. Furthermore, the biaxial hula-hoop motion parameters of the eccentric gyro ring were decided according to periodical wave motion. The magnetic flux density and electromagnetic damping of the circular Halbach-array magnetic disks were evaluated using magnetic field strength simulations and Faraday’s law of induction; comparing the difference between stator coils with cores(iron core coils) with stator coils without cores(air coils); the gap between iron core coils and circular Halbach-array disk was 4.0 mm, the magnetic flux density of circular Halbach-array disk was 24.08% higher than that air coils. According to the simulation, when the electromagnetic damping was constant value 0.1 kg-m^2-rad/s, the power of the eccentric gyro ring in biaxial hula-hoop motion was approximately 10.36 W, approximately one hundred times of that in reciprocating motion; when the electromagnetic damping substituted as electromagnetic damping equation, the power of the eccentric gyro ring with iron core coils was approximately 0.169 W, approximately 172% higher than that with air coils in biaxial hula-hoop motion. The experiment validated the numerical result of voltage was fit to the experiment result of voltage, so the establishment of dynamic equations, electromagnetic damping equations and cogging torque equations were approved.