Vibration energy harvesting from heavy haul railcar vibrations using a two-degree-of-freedom coupled oscillating system

Abstract

This paper investigates the design and fabrication of an energy-harvesting device for converting the kinetic energy of heavy haul railcar vibrations into electrical energy. The inertial-based electromagnetic generator is a two-degree-of-freedom (2-DoF) coupled oscillating system that can efficiently operate at the two dominant frequencies corresponding to unloaded and loaded railcar conditions. Vibration measurements from the field indicate the dominant frequency of the railcar at a sprung location shifts between 14.6 and 5.8 Hz for the unloaded and loaded conditions, respectively. Design and optimization was investigated using multi-physics finite element analysis (COMSOL) with sinusoidal vibration input. A prototype was developed to demonstrate that a practical amount of power can be generated using the 2-DoF coupled system. Experimental results favourably agree with model predictions, and show that more than 200 mW of output power can be generated at each dominant frequency from a 0.4 g peak sinusoidal host acceleration (where g = 9.8 m/s²). In addition measured railcar vibration was replicated using a power spectral density approach, allowing prediction to be made about the performance of the generator in the field.