6 April 2009 Novel two-stage piezoelectric-based electrical energy generators for low and variable speed rotary machinery
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Abstract
A novel class of two-stage piezoelectric-based electrical energy generators is presented for rotary machinery in which the input speed is relatively low, varies significantly over time, and is even reversing. This class of energy generators is highly suitable for applications such as wind mills, turbo-machinery used to harvest tidal flows, and the like. Current technology uses magnet-and-coil-based rotary generators. However, to make the generation cycle efficient, gearing or other similar mechanisms have to be used to increase the input speed to the generator. Variable speed-control mechanisms are also usually needed to achieve high mechanical to electrical energy conversion efficiency. This novel class of electrical energy generators uses a decoupled two-stage system. The harvesting environment (wind, tidal flow, etc.) directly provides input to the primary system. The low and varying input motion is then used to successively excite an array of vibrating elements (secondary system). The key advantage is that by having two decoupled systems, the low speed and highly varying input motion is converted into constant and much higher frequency mechanical vibrations, which are then harvested using piezoelectric elements. As a result, by eliminating the need for gearing and speed control mechanisms, the system complexity and cost - including those related to maintenance and service - is significantly reduced. Additionally, these novel generators can expand the application of power generation to much slower input speeds than are harvestable using current technology.
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J. Rastegar, J. Rastegar, R. Murray, R. Murray, } "Novel two-stage piezoelectric-based electrical energy generators for low and variable speed rotary machinery", Proc. SPIE 7288, Active and Passive Smart Structures and Integrated Systems 2009, 72880B (6 April 2009); doi: 10.1117/12.815764; https://doi.org/10.1117/12.815764
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