Energy harvesting from heavy haul railcar vibrations

Vibration energy harvesting has shown promise as technique for powering sensor networks and wireless devices. Previously, a biaxial vibration energy harvester approach was reported that used a wire-coil transducer and a permanent magnet/ball-bearing arrangement. In response to host accelerations the ball-bearing (i.e. proof mass) oscillates with two translational degrees of freedom, hence producing a varying magnetic field across the coil and therefore inducing an electromagnetic force (EMF) that could potentially be used to power a sensor. Vertical host accelerations, somewhat stochastic in nature, were measured from the bogie of a heavy haul railcar. The measured railcar accelerations were filtered, and replicated in a laboratory environment using a vibration shaker arrangement. The shaker arrangement was used to excite a non-optimised prototype energy harvester which employed a steel ball-bearing proof-mass with 31.8 mm diameter. The harvester, when excited by stochastic vibrations similar to those found on a railcar (and having an RMS acceleration of 4.16 ms^-2), produced a peak power of 1.71 mW and a longer term RMS power of 874 μW.