Design and characterization of an amplitude-limiting rotational piezoelectric energy harvester excited by a radially dragged magnetic force

Abstract

In order to avoid the damage of piezoelectric vibrator due to excessive deformation during resonance, an amplitude-limiting rotational piezoelectric energy harvester excited by a radially dragged magnetic force was presented in this paper. The amplitude-limiting device consisted of two springs and a wedge cam to limit deformation of the piezoelectric vibrator. Simulation analysis and tests were carried out to obtain the influence of system parameters on the response characteristics of the piezoelectric vibrator. The results showed that the amplitude-limiting device could effectively limit the maximal deformation and output voltage of the piezoelectric vibrator. The maximum generated voltage increases with the increases of the wedge cam lift, but the optimum speed range decreases. The effective speed range increased with the decreasing number ratio of exciting magnets and the rising spring stiffness. Moreover, a combination of a high-stiffness return spring and a low-stiffness buffer spring is helpful to enhance the effective speed range and to decrease the fluctuation of output voltage. Therefore, the energy generation capability and bandwidth of the energy harvester could be effectively improved through reasonable parameter matching. Under the load resistance of 40 kΩ, the maximal output power of 2.3424 mW is achieved at the rotating speed of 183.7 rpm.