Electromagnetic energy harvesting from train induced railway bridge vibrations

Monitoring the structural health of bridges can get rid of catastrophic failure and subsequent human casualties and avoid traffic delays. This paper proposes a novel electromagnetic energy harvester using half-wave mechanical rectification mechanism for railway transportation via train-induced bridge vibration. The proposed electromagnetic energy harvester can convert the bidirectional reciprocating translational motion into rotary motion using half-wave mechanical rectification mechanism. Dynamics of the proposed system are analyzed in both the mechanical and electrical domain. Simulation results indicate the proposed system can generate around twofold the average power at the target frequency and maintain larger power output in the desired frequency range compared with the counterpart traditional non-rectification system. The mechanical efficiency of the proposed half-wave mechanical rectification system would be higher than the traditional non-rectification system and is related with the mechanical damping ratio, mass ratio and excitation frequency. Bench tests under both harmonic excitation and real train-induced bridge vibration are carried out to verify the dynamic modelling and system characteristics. Bench test results show the proposed system can generate 17.22 W average power under 4 Hz/5 mm harmonic excitation and 7.47 W average power under an arch bridge traversed by high-speed (350 km/h) trains. Both theoretical analysis and experiment results indicate the proposed system can generate promising electricity and become a distributed power system to sensors, actuators and electronics of railway transportation and realize construction automation.