PVF2 bimorphs as active elements in wind generators

Abstract

The application to wind electric generation of bimorphs constructed of two sheets glued back-to-back of the piezoelectric polymer poly(vinylidene fluoride), or PVF2, is discussed. First, some fundamentals of piezoelectric behavior and of cantilever beam oscillations are reviewed. Then test results are presented for electrically driven PVF2 bimorphs oscillating in air and in vacuum, from which damping factors are derived. Next, two particular vertical axis wind generator designs are described employing such oscillating cantilever bimorphs which are forced into oscillation by the alternating direction of the wind forces acting on them during each rotor revolution. Wind tunnel test results for both designs are presented. Finally, the effect of possible improved polymer properties on generator output and cost is discussed.