Abstract：Piezoelectric stack has the advantages of high longitudinal electro-mechanical coupling coefficient and strong fatigue resistance, but its electro-mechanical conversion efficiency is not high under low frequency vibration, which limits its applications in vibration energy harvesting. A novel oscillator piezoelectric energy conversion system (OPECS) is presented to enhance conversion efficiency of OPECS nearby resonant frequency, through attaching an oscillator onto the surface of piezoelectric stack. The parameter model of the OPECS is built at first. According to the model electro-mechanical conversion efficiency is evaluated by ratio between longitudinal force and exciting force. Then the relationship between effective working bandwidth and structure parameters are ascertained, thus the design principles of structure parameters are given out. Experimental results show that OPESC can effectively increase the electro-mechanical conversion efficiency in low frequency vibration and enhance the output voltage of piezoelectric stack.
2011, Vol. 30 
