An Electromagnetic Bistable Energy Harvester for Wireless Health Monitoring Nodes on Freight Train Bogies

Monitoring the operational status of freight train bogies with sensors, such as accelerometers and temperature sensors, provides crucial data for accurate fault prognostics and health management of axle bearings and bogie frameworks. However, monitoring sensors on freight train bogies cannot be powered by centralized sources, and the use of chemical batteries has limitations. These energy supply issues hinder the development of PHM systems for heavy-duty freight vehicles. This paper designs an electromagnetic energy harvester based on ring-moving magnets, which converts mechanical energy from the freight train bogies into electrical power for powering sensors. Initially, the vibration characteristics of the bogie are analyzed using a 80 open wagon model to determine the design requirements. Bistability is achieved through magnetic forces, spring elasticity, and the gravitational force on the moving ring magnet, with an analysis of how changes in the inner diameter of the fixed ring magnet affect the bistable potential well to derive the optimal dimensions of key components. The prototype was tested under conditions similar to those of freight train operations. The results show that the energy harvester has a frequency bandwidth of 5-35Hz and generates an average power of 19.56mW at 20Hz and 2.5g. This harvester can provide stable power to sensors on freight trains and is suitable for the actual operating conditions of freight vehicles.