A Novel Sensor for Vibration Frequency Measurement With Piezoelectric Kinetic Energy Harvesting

In this paper, converting the kinetic energy into electrical energy by tracking the vibration frequency automatically, a vibration sensor with energy harvesting capability for the real-time measurement of vibration frequency is proposed and verified for the first time according to the authors' knowledge. The frequency measurement and energy conversion are achieved by the aid of a piezoelectric energy harvesting device (PZ EHD). A highly efficient energy harvesting circuit based on Bias-Flip technique is adopted to harvest power efficiently from the PZ EHD. An adaptive switch control circuit is used to trigger the Bias-Flip switch automatically. And a signal conditioning circuit is designed to measure the vibration frequency. In addition, an experimental setup has been designed and fabricated. It is demonstrated experimentally that the proposed system is able to measure the vibration frequency from 80 to 130 Hz. The measured frequency presents an average relative error of 0.041% after calibration. What's more, the system is able to harvest enough energy that covers the power consumption of the system over the frequency range of 96-116 Hz under 2-g acceleration with about 74% Bias-Flip efficiency.

I. Introduction

Vibration measurement is an important topic in mechanical and electrical industries. The measurement of vibration frequency is widely used to monitor industrial machines. So far, vibration sensors with different principles have been developed for frequency measurement [1], [2]. Vibration sensors are usually designed to operate on a fixed energy source like a battery. But the battery has a limited lifetime, and importantly it is often impractical to take prompt actions to replace batteries in the wireless cable-free application [3]–[6]. In addition, the use of batteries has resulted in serious environmental problems [7]. Because the limited power supply is very crucial for vibration sensors [8], self-powered techniques become increasingly attractive and have been paid attention in the literature [9]–[12].