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Proceedings Paper

Optimization of power generation from energy harvesters in broadband stochastic response
Author(s): J. T. Scruggs
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Paper Abstract

This paper presents recent analytical results pertaining to the optimization of power flow from vibratory energy harvesting systems, using principles from optimal feedback control and network theory. Historically, much of the research concerning such technologies has presumed that the vibratory energy source, from which power is to be extracted, oscillates harmonically at a known frequency. In this case, the optimization of power extraction from such sources by a resonant energy harvester can readily be accomplished through the use of classical impedance matching techniques. However, in many applications, vibratory power sources exhibit dynamic behavior more appropriately characterized by a stochastic process. In some cases, the power spectrum of this process may exhibit a rather wide band. In such circumstances, impedance matching techniques cannot be used to optimize power flow from the harvester, because the dynamic impedance they prescribe is always anticausal. This paper presents several theoretical concepts, intended for broad application in the energy harvesting area, which can be used to optimize power extracted from broadband sources. It is shown that in the broadband case, an optimal causal impedance still exists which maximizes power generation, but in order to derive it, the dissipation in the electrical system, as well as the mechanical system, must be taken into account in the system model. Levels of power generation with this controller are compared to those of the anticausal optimal performance, as well as to control design techniques that match the anticausal impedance at the resonant frequency. It is demonstrated that such causal matching techniques can be significantly sub-optimal in broadband applications, especially when electronic conversion is relatively efficient.

Paper Details

Date Published: 6 April 2009
PDF: 10 pages
Proc. SPIE 7288, Active and Passive Smart Structures and Integrated Systems 2009, 728813 (6 April 2009); doi: 10.1117/12.815838
Show Author Affiliations
J. T. Scruggs, Duke Univ. (United States)

Published in SPIE Proceedings Vol. 7288:
Active and Passive Smart Structures and Integrated Systems 2009
Mehdi Ahmadian; Mehrdad N. Ghasemi-Nejhad, Editor(s)

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