Power density improvement based on investigation of initial relative position in an electromagnetic energy harvester with self-powered applications

Abstract

Abstract In this paper, we originally report a breakthrough in the power density of a novel electromagnetic energy harvester to scavenge ambient low-frequency vibration energy. The harvester adopted a configuration of alternating south- and north-pole magnet array, which causes a step-change in magnetic flux density, contributing to high electromotive force output. Through analysis of the coil configuration and the initial relative position between coils and magnets, the harvester can take full advantage of the abrupt flux density change, which enhances its output power significantly. Experimental results adequately validated the simulation analysis regarding the correlation between the initial relative position and output power, and exhibited a high output performance. Namely, the maximum average power and power density the harvester yields are 44.8 mW and 1.6 mW c m − 3 , respectively, with the optimum resistance of 30 Ω at resonance under the excitation of 1 g. It took the harvester around 5 min to charge a button lithium battery up to 21%. Meanwhile, a LED array composed of 180 diodes was successfully lighted up, and a calculator was powered for around 630 s within a 20 s of charging period. This research shows great potential in the development of self-powered systems.