[304] Energy harvester-powered condition monitoring in high dynamic range environments

A Wasenczuk

Perpetuum Ltd, Romsey, Hampshire SO51 9DL, UK. 
Tel: 44 (0)23 8076 5888; Email: adam.wasenczuk@perpetuum.com 

Power for condition monitoring in difficult environments, such as the axlebox of a rail vehicle, is most conveniently supplied wirelessly by vibration energy harvesting. Vibration from the wheel-rail interface is Gaussian, but with a rapidly varying root mean square (RMS). The challenges of this high dynamic range environment are reliability and power conversion efficiency. An important technique is control of the load impedance presented to the energy harvester, depending on harvester internal losses represented by a ‘virtual’ shunt resistance R0. Transducer impedance obstructs direct measurement of R0. Here, the authors present a novel technique for the measurement of R0 as a function of vibration level, together with results from a Perpetuum energy-harvesting device, and predictions of optimal load lines.