Dynamical Behavior of Frequency up-Converted Piezoelectric Vibration Energy Harvesters at Different Velocities of Magnetic Interaction

This work proposes an experimental investigation on the dynamical behavior of a magnetically frequency upconverted piezoelectric energy harvester. The magnetic interaction arises between a tip magnet on a piezoelectric bimorph and a moving magnet. The latter is controlled through a low-frequency shaker at a fixed frequency of 3 Hz ( typical of human motion). The analysis shows that the activation of the first mode of vibration is linked to the velocity of the magnetic interaction. Also, inherent material nonlinearities appear as a frequency shift of the first mode on the Fast Fourier Transforms of the output voltage near short circuit condition.