Design, modeling and optimization of an N-shape electromagnetic energy harvester for smart bearing of high speed train

Abstract

Smart bearings have integrated sensors and processor and could monitor the real time status of the mechanical equipment. To achieve a long-term service of the smart bearing without human maintenance, the self-powering capability is of great necessity. This paper proposes an N-shape electromagnetic energy harvester (NEMEH) with cylindrical Halbach array embedded within an axle box bearing for the high speed train. The proposed electromagnetic energy harvester is radially embedded in the smart bearing, which includes arc-shaped magnets, an N-shape electric steel and coils. The arc-shaped Halbach array and the N-shape electric steel form a concentrated and closed magnetic flux path, which could improve the magnetic performance of the harvester. A magnetoelectric coupling model of the proposed harvester is derived and shows good agreement with the finite element analysis. An optimization route is performed to maximize the output power under the dimension constraint of the smart bearing. Experimental results demonstrate that the proposed theoretical model can well estimate the output of the harvester. The power generation of a prototype with optimal structure parameters could reach 4.26 W at a 1200 r min−1 rotational speed and a 2 mm air gap. It demonstrates that the developed NEMEH is capable of harvesting rotational motion energy to power the wireless sensor nodes.