FR4-based electromagnetic energy harvester for wireless tyre sensor nodes

Abstract

An electromagnetic (EM) power generator having 46 Hz resonance frequency is designed to scavenge mechanical vibrations occurring in tyres due to lyre-road contact. The major innovation is the use of FR4 as a structural spring material as well as utilizing a spacer and stopper mechanism increasing the shock resistance by limiting the maximum deflection. The novel magnet assembly and spacer design provide high power density. The tangential acceleration waveforms of typical tyre rotation is used as an input in the experiments and 0.4 mW power is obtained over a 100 Omega load resistance for 15g peak-to-peak amplitude at 22,83 Hz, corresponding to about 150 kph vehicle speed. Maximum acceleration is limited with the shaker, larger power values are expected in actual operation. The performance is obtained off-resonance and superior to resonant Silicon MEMS based scavengers.