Study on a piezo-disk energy harvester excited by rotary magnets

A piezo-disk energy harvester excited by rotary magnets (PEHRM) was presented to harvest energy from rotating structures. The excitation force exerted on the piezo-disk is general periodic instead of harmonic. 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 its response performance in terms of optimal rotary speeds and effective range of speeds. And then, several PEHRMs consisting of different piezo-disks were fabricated and tested. Research results show that, the wave-forms of amplitude-ratio/output-voltage in an excitation period are multimodal damped oscillations. The maximal amplitude-ratio/output-voltage is picked out and used to denote response performance. Under other parameters given, multiple optimal speeds of excited magnets can make the maximal amplitude-ratio/generated-voltage achieve the peak. With the increasing of piezo-disk stiffness denoted by radius and thickness, the optimal rotary speeds increase and the related voltage as well as voltage fluctuation decrease. These phenomena are helpful to enhance effective bandwidth and reliability. Besides, the optimal speeds, the relevant voltage and effective bandwidth also depend on the number of excitation magnets. The decreasing of exciting magnets is beneficial to enhancing the optimal speed, effective bandwidth and reliability.