Design of Broadband Response Two Degrees of Freedom Piezoelectric Vibrator for Energy Harvesting

Piezoelectric vibrator is the core of ambient energy harvesters utilizing piezoelectric effect. The developed piezoelectric vibrators are generally one degree of freedom (DOF) vibration systems with narrow resonant frequency bandwidth, which restricts the energy harvesting efficiency. This paper studies a design of two DOF piezoelectric vibrator consisted of two single DOF vibrators and a connecting spring to extend the resonant frequency bandwidth. By adjusting the structural parameters, two natural frequencies of the vibrator are set to adjacent values, so that it can maintain a high response rate over a wide frequency range near its two resonance points. Structural parameters for maximizing the power output of the vibrator are optimized by using ANSYS software. Contrastive analysis between a typical cantilevers array and the proposed vibrator is performed. The results show that the proposed vibrator has better broadband response and the design scheme is effective.