圧電素子を用いた自己給電型超音波センサの発電回路の検討

抄録

The purpose of this research is to develop a self-powered ultrasonic sensor device that can be embedded in a structure without power wiring or batteries. To this end, a single piezoelectric element is used in this study as an actuator, a sensor, and an energy harvester to realize a fully self-contained sensor network-based structural health monitoring system. This paper focuses on the efficiency of the piezoelectric power generation mechanism to understand how much energy is expected when the piezoelectric element attached to the surface of a plate structure deforms by the vibratory deformation of the host plate. A mathematical model of the piezoelectric element is derived based on the elementary plate theory, and the power consumption at a load resistance is evaluated. The strain energy of the piezoelectric element is also evaluated theoretically, and the efficiency of the energy harvesting is defined as the ratio of the consumed energy to the maximum strain energy in a half period. It is shown that the efficiency calculated from the proposed model with a modification coefficient is approximately 10^-5, which agrees well with the experimental result.