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An Effect of Coupling Factor on the Power Output for Electromagnetic Vibration Energy Harvester
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1  University of Nottingham Ningbo China
Academic Editor: Stefano Mariani (registering DOI)

Sensors are devices that measures a change in physical stimulus by converting it into an electronic signal which can be read by a designated instrument. Notable sensing application include among others vibration sensing, pressure sensing, temperature sensing, Humidity sensing, strain sensing, biosensing and structural health monitoring (SHM). Structural health monitoring relies on the automatic detection of anomalous behavior of structures. Any localized damage in a structure reduces the stiffness thereby increases damping in the structure. Reduced stiffness and or increased damping causes a decrease in the natural frequencies and hence a modification of the vibration modes of the structure. Effective study of this dynamic characteristic is very important as a robust method for quantifying assurance of their integrity and mechanical health because an unpredicted failure may be devastating on economic, social, and human life. Powering SHM devices/sensors remotely and autonomously in a passive, efficient, ecofriendly, and minimum retrofitting cost has been a major desire over the past decades. A device that meets such specification is the vibration energy harvester. This work focuses on the electromagnetic transduction harvester whose harvested voltage/power is formulated from Faraday law of electromagnetic induction. Electromagnetic parameter that determines the degree of transduction is called the coupling constant The value of coupling constant must accurately set during harvester design because it directly determines harvester damping ratio and the power available for the sensor. All parameters used to compute the coupling except the flux density is constant. In this work, we focus on formulating set analytical equation that could effectively determine the harvester’s optimum magnetic flux parameter to be used in computing the optimum coupling constant. This work concludes that the degree of coupling for the determined optimum flux density increases with an increased load resistance and hence larger harvested power is available to power the sensor.

Keywords: Structural Health Monitoring; Coupling constant; Flux density; Coil fill factor; Coil effective length; Vibration energy harvesting