Study on a piezo-windmill for energy harvesting

A piezo-windmill excited by rotating magnets was presented to harvest energy from wind of low speed and wide range speed. The exciting force exerting on the piezo-windmill is general periodic (inharmonic). An analytical model for performance evaluation was established based on Fourier series as well as superposition principle and simulated to obtain the influence of system parameters on the response of the piezo-cantilever in terms of the number of optimal rotary speeds and the relative amplitude ratio. A prototype was fabricated and tested to prove the analysis results. The research results show that, under other parameters given, there are multiple optimal rotary/wind speeds for the amplitude-ratio/generated-voltage to achieve peak. With the increasing of the number of exciting magnets, the number of the optimal rotary/wind speeds decreases. There is a moderate quantity of exciting magnets for the peak amplitude-ratio/generated-voltage to achieve maximum. Besides, with the increasing of proof mass, the optimal speeds decreases, and the relative amplitude-ratio/generated-voltage increases.