冷凝管自动弯管机切割部分设计(外文翻译)

Two-layered piezoelectric bender device for micro-power generator

Abstract：In this study, we investigated the possibility of use of bender type piezoelectric devices. To match the external vibration frequency with the device resonant frequency, the various devices with different resonant frequency were chosen. The two-layered device consists of different thick layers, in which each layer shows different resonant frequency. The highest power was obtained under optimization of the capacitive nature of piezoelectric device which is connected to small storage capacitor and its impedance matching by selection of suitable resistive load. Under an external vibration acceleration of 0.1G at 120 Hz, the device exhibited a peak-to-peak voltage of 2.0V and a power of 0.5mW in resonance mode.

Keywords：Piezoelectric ceramics Bender device Micro-power harvesting

1.Introduction

Wearable and ubiquitous micro systems will be greatly growing and their related devices should be self-powered in order to avoid the replacement of finite power sources, for example,by scavenging energy from the environment. With ever reducing power requirements of electronic circuits, power scavenging approaches are in reality. One approach is to drive an electromechanical converter from ambient motion or vibration.Vibration-driven generators based on electromagnetic,electrostatic and piezoelectric technologies have been demonstrated. Although some of the generators have already been fabricated and evaluated, their performances are behind the requirements of self-powered system. Among various generator types proposed so far, piezoelectric generator possesses considerable potential in micro system. In the system, piezoelectric device exhibits high voltage and power at a specific frequency where its resonant frequency accounts for vibrational natural frequency for achieving high efficiency in transforming from external mechanical vibration energy into electric energy.

To enhance mechanical-to-electric energy conversion, several considerations were proposed in piezoelectric device,which are searching high conversion material (high d×g (figure of merit)),matching resonant frequency of piezoelectric device with natural frequency of environmental vibration source, finding novel power conditioning and its power management technique. Among such considerations, matching the resonance frequency of piezoelectric device with that of external vibration source is the most realistic method in scavenging system based on piezoelectricity. That is,one can acquire high conversion power by designing piezoelectric device in a way that it activates in resonance mode in response to external vibration. However, the difficulty of employing such mode lies on the fact that environmental vibration is not in static state but in variable state. To overcome