Efficiency Enhancement of a Cantilever-Based Vibration Energy Harvester

Abstract

Extracting energy from ambient vibration to power wireless sensor nodes has been an attractive area of research, particularly in the automotive monitoring field. This article reports the design, analysis and testing of a vibration energy harvesting device based on a miniature asymmetric air-spaced cantilever. The developed design offers high power density, and delivers electric power that is sufficient to support most wireless sensor nodes for structural health monitoring (SHM) applications. The optimized design underwent three evolutionary steps, starting from a simple cantilever design, going through an air-spaced cantilever, and ending up with an optimized air-spaced geometry with boosted power density level. Finite Element Analysis (FEA) was used as an initial tool to compare the three geometries' stiffness (K), output open-circuit voltage (Vave), and average normal strain in the piezoelectric transducer (εave) that directly affect its output voltage. Experimental tests were also carried out in order to examine the energy harvesting level in each of the three designs. The experimental results show how to boost the power output level in a thin air-spaced cantilever beam for energy within the same space envelope. The developed thin air-spaced cantilever (8.37 cm3), has a maximum power output of 2.05 mW (H = 29.29 μJ/cycle).

High energy conversion efficiency in Mn‐modified Ba0.9Ca0.1Ti0.93Zr0.07O3 lead‐free energy harvester

“…In general, energy conversion efficiency is an important parameter to evaluate the ability to convert energy into another energy. In our work, the periodic vibration of the cantilever was assumed to follow the harmonic motion, thus, electromechanical energy conversion efficiency (η) can be calculated by the following formula: where E inp is input mechanical energy to entire cantilever beam, E outp is output electric energy to external resistor, z 0 is the amplitude of oscillation at position of the centroid, T is an oscillation cycle, F 0 is the amplitude of the harmonic excitation force (, m is mass of entire cantilever beam, a 0 is amplitude of vibration acceleration), P is the average output power. Figure C plots the η value of the BCTZ‐based energy harvester.…”

“…In general, energy conversion efficiency is an important parameter to evaluate the ability to convert energy into another energy. In our work, the periodic vibration of the cantilever was assumed to follow the harmonic motion, thus, electromechanical energy conversion efficiency (g) can be calculated by the following formula: 31,32 g ¼…”

A micro-capacitive pressure sensor design and modelling

“…In a separate article (Kubba and Jiang, 2013), the author developed a vibration-based energy harvester which was eventually used to power the presented lambda diode readout and transmission unit.…”

A low frequency lead‐free piezoelectric energy harvester with high‐power density

“…Further, the periodic vibration of the cantilever is assumed to follow harmonic motion, allowing the electromechanical energy conversion efficiency (η) to be calculated. by the following formula:η = E outp /E inp = P·T/(π·F 0 ·z 0 ), where Einp is input mechanical energy to entire cantilever beam; Eoutp is output electric energy to external resistor; z 0 is the amplitude of vibration at position of the centroid; T is an vibration cycle; F 0 is the amplitude of the harmonic excitation force; P is the average output power. As can be seen from Figure E, with the increase in the number of proof masses, the η value of the BCTZ‐based energy harvester decreased from 8.9% to 4.3%, which could be due to the increased mechanical loss.…”