Energy harvesting for heavy haul rail application

Abstract

Heavy haul vehicles operating in remote regions are particularly vulnerable to compounding deterioration due to the high levels of mechanical stress during operation coupled with low levels of maintenance inspection. The application of structural health monitoring is appealing in this operating environment due to its autonomous nature, and the potential cost savings due to early detection of mechanical damage. Without any monitoring system in place, predicting the reliability and mechanical failure modes of heavy haul rail vehicles is difficult. However autonomous structural health monitoring systems such as the Instrumented Ore Car (IOC) allow early detection of rail and vehicle anomalies to minimise damage and reduce the risk of derailment leading to significant down time and cost. A particular issue experienced by wireless systems is the lack of electrification. Primary batteries are often the easiest solution however they are typically not suitable due to their limited energy capacity and high maintenance cost. A more appealing solution is energy harvesting from local sources of waste energy. The ambient operating environment of heavy haul rail vehicles were examined with the aim of finding a suitable source of waste energy, and potential transduction approaches were considered. It was decided that vibration energy harvesting using electromagnetic transduction was the most suitable energy harvesting method. An inertial based 1-DoF electromagnetic energy harvester was designed and manufactured to generate practical levels of power (typically in the range of 10 - 100 mW for structural health monitoring sensor systems). The device was designed using finite element analysis and tested in the laboratory using sinusoidal and PSD input based on measured railcar vibration. A substantial amount of power was generated using the 1-DoF device with experimental results agreeing well with model predictions. Furthermore to improve power generation for heavy haul rail application, a second design was introduce utilising a 2-DoF coupled oscillating system. The 2-DoF design demonstrated significant improvements to the power generation and was installed on the railcar to provide an in-service demonstration and to validate the experimental and model predictions.