Improved Energy Harvesting from Wideband Vibrations by Nonlinear Piezoelectric Converters

Vibration harvesters typically are linear mass-spring devices working at resonance. A different approach is here proposed based on nonlinear converters that exploit stochastic resonance with white-noise excitation. A piezoelectric beam converter is coupled to permanent magnets creating a bistable system bouncing between two stable states in response to random excitation. Under proper conditions, this significantly improves energy harvesting from wide-spectrum vibrations. A cantilever beam with added nonlinearity has been simulated by using a MATLAB® Stochastic Differential Equation (SDE) Toolbox with a white-noise vibration. A nonlinear converter was then realized by screen printing low-curing-temperature lead zirconate titanate (PZT) films on steel cantilevers and excited with white-noise vibrations. Experimental results show that the performances of the converter in terms of output voltage at parity of mechanical excitation are markedly improved.