Research on Differential Triboelectric–Electromagnetic Wind Energy Harvester for Rail Transit Tunnels

Trains traveling through rail transit tunnels generate bidirectional, alternating, and intermittent piston-like airflow. Traditional wind energy collectors have problems such as poor bidirectional airflow adaptability and high starting wind speed. This paper proposes a microminiaturized bidirectional differential triboelectric–electromagnetic hybrid generator (BR-TEG). The device adopts a vertical coaxial layered configuration, integrating a triboelectric generator (TEG) and an electromagnetic generator (EMG). The upper and lower layers are assembled with wind cups facing in opposite directions, forming a differential counter-rotating structure that can adapt to the bidirectional reciprocating piston airflow in tunnels and achieve continuous wind capture from all directions. The top layer is equipped with a slip ring transmission mechanism, which resolves issues such as lead wire entanglement and unstable power generation during bidirectional rotation. Experimental results show that the BR-TEG has a minimum startup wind speed of 0.8 m/s, and at a wind speed of 9 m/s, the total peak power reaches 679.02 mW. The device, in conjunction with the energy management circuit, can stably power low-power monitoring devices such as LED arrays and Bluetooth temperature and humidity sensors. Additionally, the frequency of the device’s electrical output exhibits a strong linear correlation with wind speed, enabling it to serve both as a wind energy harvester and a tunnel wind speed monitor. In summary, the BR-TEG provides a new technical solution for the utilization of wind energy in rail transit tunnels and the construction of distributed self-powered systems for smart tunnels.