Frequency Piezoelectric Energy Harvester Research Articles

Dynamic modeling and experimental validation of a low frequency piezoelectric vibration energy harvester via secondary excitation of pressured fluid

A low frequency piezoelectric energy harvester using secondary excitation of pressured fluid is proposed in this paper to scavenge low frequency vibration energy in ambient environments. This harvester was characterized by an indirect vibration-to-electric energy converter via transferring the pressure energy of pressured liquid medium. A series of simulations and experiments were conducted to prove the good performance and the feasibility of this novel structure in low-frequency high-intensity vibration. The results showed that the diameter of damping orifice, initial system backpressure and proof mass brought strong influences on the resonance frequency and output voltage. Meanwhile, according to experiments, it was found that the resonance frequency was decreased with the decreasing liquid backpressure. In this case, lowest resonance frequency of 19 Hz was achieved under the condition of 10-kg proof mass and 0.2-MPa liquid backpressure. Also, there were the optimal proof mass and backpressure to maximize the generated voltage, respectively. Moreover, in the impedance matching experiments, the maximum output power reached 1.35mW at the matching load resistance of 18kΩ.

Magnetic coupled ultra-low frequency piezoelectric energy harvester for self-powered sensors

Harvesting human motion energy to power various sensors has attracted more and more attention of researchers. Aiming to harvest the ultra-low frequency vibration energy generated by human motion, this paper proposes a magnetic coupled scheme which consists of two flextensional transducers with two endmost magnets, a center magnet, and a tube. Through magnetic coupling effect, the ultra-low frequency vibration energy is amplified and effectively harvested, and the output voltage amplitude at 5Hz reaches 22V under the initial distance of 48mm and the acceleration of 1g. The output voltage amplitude of the harvester is related to the initial distance and excitation acceleration which are theoretically analyzed in this paper.

Numerical and experimental evaluation of the magnetic interaction for frequency up-conversion in piezoelectric vibration energy harvesters

The purpose of this work is to improve the modelling process for the application of permanent magnets in a frequency up-conversion (FuC) mechanism for piezoelectric energy harvesters. More specifically, the aim is to avoid the burdensome finite element analyses (FEA) in the framework of electromechanical devices design. The analytical calculations are compared with experimental tests conducted by an ad-hoc set up and with FEA. After investigations on the interaction, an application of FuC mechanism is proposed on a meso-scale case study in which a low frequency seismic mass (LFM) interacts non-linearly, due to magnetic field, with an high frequency piezoelectric vibration energy harvester (PVEH). Numerical simulations have been carried out in the time domain (step-by-step analysis) under a harmonic low-frequency input acceleration signal. The peculiar behavior, due to non-linear dynamics, is investigated in both the repulsive and the attractive configurations of the magnets. The results confirm the effectiveness of magnetic FuC and show that the repulsive case allows the device to recover a larger amount of energy than the attractive configuration.

A study of a new hybrid vibration energy harvester based on broadband-multimode

To improve the energy conversion efficiency and working frequency bandwidth of a single frequency piezoelectric vibration energy harvester, a new type of hybrid vibration energy harvester is developed which is combined with the mechanism of piezoelectric and electromagnetic energy conversion. The system comprises of a PZT cantilever beam, an elastic suspended magnetic mass, a magnet block attached to the end of the cantilever beam and a resonator. The addition of resonator can not only increase the mode, but also adjust the frequency of harvester flexibly. Nonlinear magnetic force of magnet block not only broadens the frequency band and improves the output performance of the system, but also changes the resonant frequency to make the harvester have better adjustable performance. On this basis, an improved electromechanical coupled analytical model of continuum is proposed which can be solved by the Runge-Kutta algorithm and the influence of different factors (the mass and spring stiffness of the resonator, as well as the electromechanical coupling coefficient, electromagnetic coupling coefficient, magnet mass and magnetic flux) on the output are analyzed. According to the prototype of the vibration energy harvester developed, an experimental system was built. The performance of the independent and hybrid energy harvesters is evaluated by experimental and analytical methods. The peak output voltage of the piezoelectric part was about 4 times that of the electromagnetic part. The peak output current of the electromagnetic part is about 30 times that of the piezoelectric part. The study results show that the proposed new hybrid vibration energy harvester can achieve a wider frequency range and multimodal vibration energy harvesting. In addition, the bandwidth and power of the harvester can be dynamically adjusted by changing the resonator or electromechanical coupling coefficient, and the bandwidth of the harvester can also be adjusted by changing the quality and characteristics of the magnet.

Investigation of an ultra-low frequency piezoelectric energy harvester with high frequency up-conversion factor caused by internal resonance mechanism

The collection of ultra-low frequency mechanical energy that distributed in ambient environments remains challenging so far. This paper presents a frequency up-converting energy harvester based on a component pendulum, a pair of magnetic coupled cantilever beams, and two mechanical stoppers. The pendulum-like oscillator with ultra-low natural frequency can efficiently capture ambient mechanical energy and the designed 1:2:6 internal resonance mechanism can up-convert the frequency with a high conversion factor, presenting great potential for application in real-world systems with low vibration frequencies in the range of 1 to 5 Hz. Modeling and design are conducted, theoretical dynamic predictions are given and confirmed by experimental results. The proposed frequency up-converting harvester could generate a relatively high output power (about 2 mW) at a low excitation frequency and amplitude (around 2 Hz and 0.37 g). Moreover, the electromechanical coupling coefficient of the harvester can be further optimized, increasing the above-mentioned output power directly.

Performance improvement of low frequency piezoelectric energy harvester incorporating holes with an in-house experimental set-up

The piezoelectric energy harvesters can be an integral part of self-powered sensor system due to its compatibility with semiconductor technology. In this paper, a modified structural geometry has been proposed in order to improve the performance of energy harvesters with classical cantilever topology by incorporating through holes. A detail mathematical analysis has been carried out to manifest the effect of through hole on resonant frequency of piezo harvester using Rayleigh–Ritz method. The theoretical analysis is validated through simulation studies as well as experimental results. Accordingly, an in-house low cost experimental set-up has been developed using Polyvinylidinefluoride (PVDF) based macro-level energy harvester and loud speaker based vibration set-up. It has been observed that the resonant frequency is reduced from 26.23 Hz to 21.94 Hz due to incorporation of hole to classical cantilever for a given dimension. With input acceleration of 3.7 g, the developed macro-harvester set-up resonates at 23 Hz and is capable of producing power of 59.93 $$\mu$$ W with hole based structure whereas power of 14.60 $$\mu$$ W is obtained in case of without hole based structure. The macro-scale energy harvester with modified geometry has been also designed and simulated in finite element analysis method to validate the mathematical analysis and it is found that lower the resonant frequency higher the power obtained with the hole based topology. It is verified from the experimental, simulation and theoretical studies, that there is a dominant effect of through hole in the performance improvement of piezoelectric energy harvester.

A broadband piezoelectric energy harvester with movable mass for frequency active self-tuning

A broadband active self-tuning frequency piezoelectric energy harvester (AST-PEH) is proposed in this paper. It consists of a piezoelectric cantilever beam, an energy harvesting and control circuit (EHCC), a miniature stepper motor, a screw rod and a T-section mass. It can actively adjust the position of the T-section mass according to the ambient vibration frequency. It matches the AST-PEH’s resonant frequency with the ambient vibration excitation frequency, and it widens the operating frequency range of the AST-PEH. The expression of the AST-PEH’s resonant frequency function is constructed based on the dynamic and static theoretical analysis. The theoretical model of the AST-PEH under different position of the T-section mass is analyzed by ANSYS15.0 APDL, which is verified by two different materials and sizes. The tested two type substrate materials are steel and polylactic acid (PLA). The experimental results show that the frequency range of the two type harvesters are 4.8 Hz–6.3 Hz and 8.17 Hz–14.3 Hz respectively, and the widening rates of the working frequency are 31.25% and 75% respectively. The tested maximum output power of steel type AST-PEH is 0.32 mW at 6.3 Hz under 0.32 g acceleration and with a 100 KΩ load resistance.

A Low Frequency Vibration Energy Harvester Using ZnO Nanowires on Elastic Interdigitated Electrodes.

This paper presents a low frequency piezoelectric vibration energy harvester using ZnO nanowires on elastic interdigitated electrodes. The interdigitated electrodes are formed using electroplated Ni and have suspended parts at the edges that are elastic and deformable by applying external force. A spherical Ni ball is used as a proof mass, which transforms a low frequency mechanical vibration into the force applied to deform the elastic electrodes. The ZnO nanowires are grown selectively on the electrodes and can generate a piezoelectric potential when the elastic electrodes are deformed by the proof mass activated by the external mechanical vibration. The proposed operation concept is demonstrated using two different types of energy harvesters, which have simple suspended part and cantilever array structures added to the electrodes, respectively. The output voltage of the fabricated harvesters is measured using a vibration exciter at 6 Hz sinusoidal vibration with an acceleration of 0.5 g. Maximum output power of 12.8 pW and 18.8 pW was generated with a load resistance of 1 MΩ for the harvesters using the simple suspended structure and cantilever array, respectively.

A MEMS based piezoelectric vibration energy harvester for fault monitoring system

Normally, the ambient vibrations demonstrates low acceleration amplitude (< 1 g) and low frequency (60–300 Hz), so most researchers focus on the study of the low frequency vibration energy harvester at present. However, the power output of the low frequency vibration energy harvester is low and thus difficult to meet the application requirement. In this paper, a MEMS based piezoelectric vibration energy harvester was designed and fabricated for the application of the fault monitoring system for ship engine which vibrates at high acceleration amplitude and high frequency. Firstly, the vibration characteristics of the ship engine was tested. Under normal operating conditions, the vibration frequency and acceleration of the ship engine are 600–700 Hz and 2–4 g, respectively. And then a MEMS based high frequency piezoelectric vibration energy harvester was designed under the vibration environment. Finally, the designed harvester was fabricated and evaluated. The voltage and power output of the fabricated harvester is 5.81 V and 660.1 μW, which meet the application requirements of the fault monitoring system.

Vibro-Shock Dynamics Analysis of a Tandem Low Frequency Resonator-High Frequency Piezoelectric Energy Harvester.

Frequency up-conversion is a promising technique for energy harvesting in low frequency environments. In this approach, abundantly available environmental motion energy is absorbed by a Low Frequency Resonator (LFR) which transfers it to a high frequency Piezoelectric Vibration Energy Harvester (PVEH) via impact or magnetic coupling. As a result, a decaying alternating output signal is produced, that can later be collected using a battery or be transferred directly to the electric load. The paper reports an impact-coupled frequency up-converting tandem setup with different LFR to PVEH natural frequency ratios and varying contact point location along the length of the harvester. RMS power output of different frequency up-converting tandems with optimal resistive values was found from the transient analysis revealing a strong relation between power output and LFR-PVEH natural frequency ratio as well as impact point location. Simulations revealed that higher power output is obtained from a higher natural frequency ratio between LFR and PVEH, an increase of power output by one order of magnitude for a doubled natural frequency ratio and up to 150% difference in power output from different impact point locations. The theoretical results were experimentally verified.

A low frequency piezoelectric energy harvester with trapezoidal cantilever beam: theory and experiment

With the development of low power MEMS device and outdoor wireless sensor network, new energy supply has been a key to replace the traditional energy which has some disadvantages. We have found that obtaining energy from the daily low frequency vibration environment is a very efficient solution to ease the pressure of energy sources. In this paper, a utility low frequency piezoelectric energy harvester with trapezoidal cantilever beam is presented. Then, a relevant theoretical model, optimization method and comparison experiment are made. The results show that the theoretical analysis results are in agreement with the experimental results; under the condition of constant beam length, open-circuit voltage and output power of the trapezoidal beam piezoelectric energy harvester are 81.6 and 167% more than those of the rectangular beam piezoelectric energy harvester. In addition, In order to further broaden the frequency band and improve output characteristics, we use the nonlinear method to redesign the experiment based on the above experiments. The results show that distance and magnet polarity change have an important effect on output characteristics.

A low frequency MEMS energy harvester scavenging energy from magnetic field surrounding an AC current-carrying wire

This paper reports on a low frequency piezoelectric energy harvester that scavenges energy from a wire carrying an AC current. The harvester is described, fabricated and characterized. The device consists of a silicon cantilever with integrated piezoelectric capacitor and proof-mass that incorporates a permanent magnet. When brought close to an AC current carrying wire, the magnet couples to the AC magnetic field from a wire, causing the cantilever to vibrate and generate power. The measured average power dissipated across an optimal resistive load was 1.5 μW. This was obtained by exciting the device into mechanical resonance using the electro-magnetic field from the 2 A source current. The measurements also reveal that the device has a nonlinear response that is due to a spring hardening mechanism.

Design of a Low Frequency Piezoelectric Energy Harvester for Rodent Telemetry

This work presents the design and simulation of a piezoelectric-based device to generate electrical power by harvesting the kinetic energy available from the natural movement of small animals, such as rodents. Telemetry acquisition from rodents is important in biomedical research, where rodent behavior data is used to study disease models, or in biology research, involving animal tracking. In both applications, a long-term powering scheme for telemetry electronics and radios is needed. A major challenge is the relatively small size and low frequency motion of rodents. The proposed energy harvester design is simulated and the results reported. The design consists of a cantilever beam with a piezoelectric layer, a proof mass, and motion limit pads. Its mass and size are intended for use with a rodent, to provide continuous power for monitoring without limiting rodent mobility. Maximum power is obtained when the excitation source (animal movement) frequency corresponds to the resonant frequency of the energy harvester. As well, we demonstrate that the harvester electrical impedance is important, and must match the impedance of the application circuit load, to maximize the electrical power harvested. An experiment is conducted to record typical rodent (mouse) running motion in three axes of acceleration. A power spectral density (PSD) was computed for all axes, and the highest power is observed in the x-axis (forward/backward) motion at a frequency of 11.7 Hz, which is the typical gait frequency. Hence, the proposed energy harvester has been specifically designed to resonate at 11.7 Hz. The response of the proposed design is simulated using finite element analysis (FEA) software, to predict the electrical power and proof mass displacement. The model is excited with both a pure sine wave, and also with an arbitrary waveform consisting of the actual displacement of the rodent movement. A multi-scale FEA meshing approach is used to accommodate the thin thickness and long length of the cantilever design using mapped meshes. Additionally, a transient simulation is used to simulate the proposed design with different applied excitation frequencies, to determine the ideal matched load impedance for maximum electrical power.

Nonlinear output properties of cantilever driving low frequency piezoelectric energy harvester

Cantilever driving low frequency piezoelectric energy harvester (CANDLE) has been found as a promising structure for vibration energy harvesting. This paper presents the nonlinear output properties of the CANDLE to optimize the performance of the device. Simulation results of the finite element method illustrate that nonlinear contacts between the cymbal transducers and the cantilever beam are main reasons of the nonlinear output. However, high excitation acceleration of the nonlinear leap point limits the application of the device. Based on the simulation results and theory analysis, the excitation acceleration is reduced to 30 m/s2 by increasing the proof mass.