Piezoelectric Vibration Energy Harvesting System Research Articles

Performing Magnetic Boundary Modulation to Broaden the Operational Wind Speed Range of a Piezoelectric Cantilever-Type Wind Energy Harvester

Small piezoelectric wind-induced vibration energy harvesting systems have been widely studied to provide long-term sustainable green energy for a large number of wireless sensor network nodes. Piezoelectric materials are commonly utilized as transducers because of their ability to produce high output power density and their simple structure, but they are prone to material fracture under large deformation conditions. This paper proposes a magnetic boundary modulated stepped beam wind energy harvesting system. On the one hand, the design incorporates a composite stepped beam with both high- and low-stiffness components, allowing for efficient vibration and electrical energy output at low wind speeds. On the other hand, a magnetic boundary constraint mechanism is constructed to prevent the piezoelectric sheet from breaking due to excessive deformation. Experiments have confirmed that the effective operational wind speed range of the harvester with magnetic boundary constraints is doubled compared to that of the harvester without magnetic boundary constraints. Furthermore, by adjusting the magnetic pole spacing of the boundary, the harvesting system can generate sufficiently high output power under high-wind-speed conditions without damaging the piezoelectric sheet.

Modified extended Rauch–Tung–Striebel smoother method for the dynamic external excitation identification of piezoelectric vibration energy harvesting systems

A vibration energy harvester can collect vibration energy from the environment to supply low-power devices, such as wireless sensor nodes. Reducing the size and power consumption of these devices is a challenging problem. A dual-function device, which includes energy harvesting and vibration measurement, may solve this problem. Therefore, studying inversion methods for identifying the external excitation of a harvester is meaningful. In this study, a modified inversion method that combines an extended Rauch–Tung–Striebel smoother (ERTSS) with the particle swarm optimization (PSO) algorithm, i.e., the ERTSS-PSO method, is proposed to identify the time domain signal of external excitation through the voltage response of a piezoelectric vibration energy harvester. A modified ERTSS approach with sliding windows is developed. The sliding windows are partially overlapped to eliminate identification errors between the two contiguous windows. Near real-time identification is achieved for the small sliding window. PSO is utilized to estimate state noise covariance and measurement noise covariance, improving identification accuracy compared with the L-curve approach. Under this proposed framework, prior knowledge regarding the statistical data of unknown external excitations is unnecessary, enabling a more comprehensive range of applications. To assess the performance of the proposed ERTSS-PSO method, numerical simulations, including two piezoelectric vibration energy harvesting systems with third-order and fifth-order nonlinear stiffness, are conducted to verify the effectiveness of the proposed method under harmonic, multifrequency, and random excitations. The method proposed in this study is also validated by a circular laminated piezoelectric plate harvester under harmonic and random excitations in an experiment. Results from the experimental studies demonstrate that the proposed method improves identification accuracy by at least 9% compared with the extended Kalman filter, at least 7% compared with the augmented Kalman filter (AKF) with Rauch–Tung–Striebel smoother (ARTSS), and at least 40% compared with AKF under random excitation. In addition, the proposed method is unaffected by initial conditions, and it is more stable and accurate than AKF and ARTSS. The proposed method lays the theoretical foundation for identifying the external excitation of a harvester. It is also a possible solution for the miniaturization and compactness of wireless monitoring devices.

A piezoelectric and electromagnetic vibration energy harvesting system based on spring pendulum structure and MPPT control

A piezoelectric and electromagnetic vibration energy harvesting system based on spring pendulum structure and MPPT control

Response analysis of asymmetric monostable energy harvester with an uncertain parameter

The nonlinear piezoelectric vibration energy harvesting system offers a solution to the power supply challenge for low-power sensors. However, In practical engineering, structural parameter uncertainties arise from manufacturing errors, environmental temperature fluctuations, and changes in material properties. Besides, due to inherent flaws in the structure and materials, asymmetry may occur in the potential well, which leads to the complexity of the dynamic behavior exhibited in energy harvesting system. In this paper, in order to investigate the dynamics of the asymmetric monostable piezoelectric energy harvesting system under an uncertain parameter, the orthogonal polynomial approximation method is applied to transform the stochastic system into an equivalent deterministic system. Then, the responses of the equivalent deterministic system are used to reveal the stochastic behavior of the uncertainty system. The results indicate that, when the uncertainty intensity of the cubic nonlinear coefficient is 0, an increase in the asymmetry level of the potential well leads to an increase in the output voltage. Increasing the other parameters, the output voltage is reduced. In addition, as the uncertainty intensity increases, the parameter intervals of chaotic response become wider and the energy harvesting efficiency decreases. Moreover, as the potential well asymmetry increases, the sensitivity of energy harvesting system to uncertain parameter increases.

Study on the Influence Factors on Harvesting Capacity of a Piezoelectric Vibration Energy Harvesting System Covered on Curved Beam with Acoustic Black Hole

The acoustic black hole (ABH) structures have been shown to have great potential for energy harvesting. Within an ABH, the bending wave velocity decreases rapidly and the phase accumulates, resulting in localised energy accumulation. It is very significant that the energy can be harvested and power can be supplied for microelectronic devices. How to improve energy harvesting capacity is a problem that needs to be solved. Previous research on energy harvesting capacity of straight beams and flat plates with ABH has yielded a wealth of results. However, in practical engineering, curved beams are also commonly found. Given the differences in structure, it is of practical significance to study the influence factors on harvesting capacity of the piezoelectric vibration energy harvesting system covered on curved beam with acoustic black hole. First, the vibration characteristics of curved beam with ABH are analysed by the finite element method and localised energy accumulation is observed. Then, energy harvesting capacity is studied by means of the electromechanical coupling model in FEA; it has been found that energy harvesting capacity is lower in high frequency. The reason of this problem is analysed and solved by dividing the size of the piezoelectric sheet in an array layout. Based on this, the influence of array layout of piezoelectric cells on the energy harvesting capacity of the system is focused on. In addition, the influence of resistance value, material property, and curvature of curved beam on the energy harvesting capacity is analysed. Some meaningful results are obtained. These results provide the guidance to the design and optimisation for an energy harvesting system covered on curved beam with ABH.

Performance analysis of nonlinear vibration energy harvesting system with inelastic barrier under colored noise excitation

The vibro-impact structures are introduced into the piezoelectric vibration energy harvesting (VEH) systems, which can broaden the operating bandwidth of the piezoelectric VEH systems and thus improve the harvesting efficiency. The process of vibro-impact not only causes energy loss during the impact process but also causes the local deformation between two impact bodies. Therefore, this manuscript proposes a class of stochastic non-classical inelastic impact VEH models, whose non-classical impact processes are described by Hertz contact forces. Firstly, the relationship between the total energy of the unperturbed system and the potential energy of the system at the barrier position is used to determine whether the impact phenomena have occurred or not, then used to derive the period and frequency of the system. Secondly, using the quasi-conservative stochastic averaging method, the averaged drift term and the averaged diffusion term of the piecewise smooth averaged Ito^ equation are derived. The stationary probability density functions (PDFs), the mean square output (MSO) voltage and the root mean square (RMS) voltage of the system response can be obtained from solving the corresponding Fokker-Planck-Kolmogorov (FPK) equation for averaged Ito^ equation. Finally, an example is provided to verify the effectiveness of the proposed method, and the effects of the model parameters on the MSO voltage and power conversion efficiency (PCE) are analyzed. The relationship between the MSO voltage and the PCE is also analyzed. It is of great significance for the design and optimization of stochastic VEH systems.

Low-voltage broadband piezoelectric vibration energy harvesting enabled by a highly-coupled harvester and tunable PSSHI circuit

This paper presents a system-level design approach for widening the bandwidth and lowering the operating voltage of a piezoelectric vibration energy harvesting system (PVEHS). The proposed strategy involves co-optimization of the two constituent parts: (1) a highly-coupled piezoelectric vibration energy harvesting device (PVEHD) and (2) a phase-shift tunable parallel-SSHI (PS-PSSHI) interface power-electronic circuit. First, we analyze the interaction between them to achieve an overall reduction of system voltage and to widen bandwidth. Next, a co-designed system is experimentally demonstrated to validate the analysis. The implemented PVEHS consists of (i) a customized PVEHD designed for high electromechanical coupling and well-separated short-circuit (f SC) and open-circuit (f OC) resonances, and (ii) a tunable PS-PSSHI circuit which has an active rectification with low voltage drop to increase system efficiency. The system achieves an output power of 148 µW with a bandwidth of 81 Hz, an increase of 337% compared to conventional full-bridge rectifier. In addition, the system rectification voltage is lowered by 30% which makes it viable to power low-voltage Internet-of-Things sensor nodes.

Transient response of a nonlinear energy sink based piezoelectric vibration energy harvester coupled to a synchronized charge extraction interface

Integration of a piezoelectric transducer with a nonlinear energy sink (NES) has been realized for both vibration mitigation and broadband energy harvesting. However, to ensure that a harvester can generate power in a truly broadband manner, the impedance matching issue of the interface circuit should be addressed. The synchronized charge extraction (SCE) is one technology that has been proved to be able to address this issue for linear energy harvesters. This work intends to investigate the transient response of an NES-based piezoelectric vibration energy harvesting system interfaced with an SCE interface (NESVEH-SCE). The nonlinear normal mode of such an electromechanically coupled system is analyzed on the basis of the equivalent impedance method and complexification-averaging method. The frequency-energy plots are depicted and verified by wavelet analysis. The effects of electromechanical coupling strength, electrical load in the SCE interface and initial input energy level on the performance of the proposed system are discussed by using the circuit simulation tool. Finally, experiments are performed to verify the consequences obtained from the theoretical and numerical methods, and demonstrate that the energy harvested during the transient response of the NESVEH-SCE system is independent of the electrical load in the SCE interface.

Power–bandwidth–voltage interaction in piezoelectric vibration energy harvesters with constrained load voltage

This paper analyzes the power–bandwidth–voltage interaction in a piezoelectric vibration energy harvester (PVEH) system, specifically accounting for the operating voltage constraint imposed by the interface power electronics (PE). The analysis is sufficiently generic to apply to different linear PVEHs with their interface PE. The power–bandwidth–voltage relation derived here outlines the best possible PVEH system performance when the PVEH-PE interface voltage is constrained, as is often the case in IoT applications. Alternatively, it can serve as a figure of merit with which to benchmark the performance of existing PVEH systems, and identify best design practices.

System level design of wireless sensor node powered by piezoelectric vibration energy harvesting

This paper proposes a design of wireless sensor node powered by piezoelectric vibration energy harvesting system. A complete system level coupling circuit model is established to predict the performance characteristics. The piezoelectric vibration energy harvester (PVEH) is based on a PZT bimorph cantilever, in which a big proof mass is introduced to decrease resonant frequency and a shell served as a stopper to avoid overload. Lumped parameters of the model are identified by experiments and calculations. Electromechanical analogy model of PVEH is simulated in LTspice software. The power consumption of a temperature WSN is tested and the equivalent load model is simulated. A power management circuit (PMC) with LTC3588-1 is designed for rectifying and regulating output of PVEH. Electrical energy is stored in a capacitor. Finally, a system level coupling model is established. Time domain circuit simulation can provide the detailed parameters about the WSN powered by PVEH such as full charge time and sustainable time of the system. Test curves of capacitor charging and WSN power supply in prototype testification show good consistency with the simulation results in LTspice. An application for temperature WSN powered by PVEH is testified as an example. The method and model proposed in this paper can set up a reference to optimize system parameters for WSN powered by PVEH.

A Sensorless Self-Tuning Resonance System for Piezoelectric Broadband Vibration Energy Harvesting

This article presents a broadband piezoelectric vibration energy harvesting system. It can actively tune its resonant frequency to match the frequency of the ambient vibration excitation. The energy harvester is comprised of a movable mass attached to a piezoelectric cantilever beam. And a microstepper is employed to adjust the position of the mass for regulating the resonant frequency. Furthermore, in this article, a new method is proposed for the online dynamic detection of the piezoelectric transducer (PZT) vibration statement without any additional sensors. A circuit is proposed to detect the ambient vibration excitation frequency deviation against the resonant frequency only by measuring the phase difference between the open-circuit voltage and the short-circuit current of the PZT. Experimental results indicate a frequency broadening rate of up to 60.56%, while the maximum extraction efficiency is 84.8%. It can harvest vibration energy and self-power the system in a wide broadband ambient excitation vibration frequency for the wireless sensor network nodes.

A novel low-frequency broadband piezoelectric energy harvester combined with a negative stiffness vibration isolator

The transformation of waste vibration energy into low-power electricity has been intensely researched over the last decade to enable self-sustained wireless electronic components. Many kinds of nonlinear oscillators have been explored by several research groups in an effort to enhance the frequency bandwidth of operation. The negative stiffness vibration isolator, as a kind of passive vibration isolator, has undergone extensive investigation because of its low-frequency isolator characteristics. In this article, a novel broadband piezoelectric vibration energy harvester, which can be used for low-frequency ambient mechanical energy harvesting, is designed, and its dynamic responses are analyzed based on the advantage of the negative stiffness vibration isolator. The multi-scale perturbation method is applied to solve the electromechanical equations of the piezoelectric vibration energy harvester and obtain approximate analytical solutions. Solutions based on the analytical method and numerical simulations reveal the characteristics of significant broadband performance. The effects of the various system parameters on the frequency responses and output voltage of the piezoelectric vibration energy harvester system are investigated in detail, and the vibration isolation ability is verified by experimental measurements. It was concluded that the proposed piezoelectric vibration energy harvester achieved broadband vibration energy harvesting in the low-frequency vibration range.

A tunable frequency up-conversion wideband piezoelectric vibration energy harvester for low-frequency variable environment using a novel impact- and rope-driven hybrid mechanism

This paper presents a tunable frequency up-conversion wideband piezoelectric vibration energy harvester using a novel impact- and rope-driven hybrid mechanism, in which a high frequency generating beam is triggered by the rope or impacted directly by the low frequency driving beam. A mass-spring-damper equivalent model was built to understand the operation mechanism of the proposed piezoelectric vibration energy harvester. Based on the theoretical model, the effect of the rope-margin on the performance of the proposed piezoelectric vibration energy harvester was numerically analyzed. Both the simulation and experimental results showed that the central working frequency of the proposed piezoelectric vibration energy harvester can be changed easily from 74.75 Hz to 106 Hz by adjusting the rope-margin from 0.5 mm to 2 mm without any structure re-fabrication. Moreover, a bandwidth 4.2 times wider than the conventional frequency up-conversion piezoelectric vibration energy harvester based on impact-driven mechanism can be achieved. The tunable performance of the proposed piezoelectric vibration energy harvester system make it promising for vibration energy harvesting in wideband environments with low frequency.

Feasibility of vibration energy harvesting powered wireless tracking of falcons in flight

The use of wireless tagging of birds has been widely used for monitoring or tracking purposes. This include over 10 thousand wireless tracking devices currently used by the UK falconers alone. However, due to the concern of not burdening the birds with a heavy battery, the existing lightweight telemetry tracking systems can only last for days, if not hours. Falcons can have top flight speeds in excess of a hundred miles an hour, which makes it a near impossible task to track a missing falcon after the battery has been depleted. This paper investigates the feasibility of incorporating a piezoelectric vibration energy harvesting system to act as a secondary power source for the wireless tracking of falcons. The ultimate aim is to both extend the primary battery life and enable periodic burst transmissions of telemetry after the depletion of the primary battery. The presented tracking and harvesting system is lightweight and has been field trialled on a gyrfalcon at the Chester Cathedral Falconry.

Theoretical modeling and experimental validation of a torsional piezoelectric vibration energy harvesting system

Vibration energy harvesting has been extensively studied in recent years to explore a continuous power source for sensor networks and low-power electronics. Torsional vibration widely exists in mechanical engineering; however, it has not yet been well exploited for energy harvesting. This paper presents a theoretical model and an experimental validation of a torsional vibration energy harvesting system comprised of a shaft and a shear mode piezoelectric transducer. The piezoelectric transducer position on the surface of the shaft is parameterized by two variables that are optimized to obtain the maximum power output. The piezoelectric transducer can work in d15 mode (pure shear mode), coupled mode of d31 and d33, and coupled mode of d33, d31 and d15, respectively, when attached at different angles. Approximate expressions of voltage and power are derived from the theoretical model, which gave predictions in good agreement with analytical solutions. Physical interpretations on the implicit relationship between the power output and the position parameters of the piezoelectric transducer is given based on the derived approximate expression. The optimal position and angle of the piezoelectric transducer is determined, in which case, the transducer works in the coupled mode of d15, d31 and d33.

Time-varying output performances of piezoelectric vibration energy harvesting under nonstationary random vibrations

Piezoelectric vibration energy harvesting (PVEH) has received much attention as a potential solution that could ultimately realize self-powered wireless sensor networks. Since most ambient vibrations in nature are inherently random and nonstationary, the output performances of PVEH devices also randomly change with time. However, little attention has been paid to investigating the randomly time-varying electroelastic behaviors of PVEH systems both analytically and experimentally. The objective of this study is thus to make a step forward towards a deep understanding of the time-varying performances of PVEH devices under nonstationary random vibrations. Two typical cases of nonstationary random vibration signals are considered: (1) randomly-varying amplitude (amplitude modulation; AM) and (2) randomly-varying amplitude with randomly-varying instantaneous frequency (amplitude and frequency modulation; AM-FM). In both cases, this study pursues well-balanced correlations of analytical predictions and experimental observations to deduce the relationships between the time-varying output performances of the PVEH device and two primary input parameters, such as a central frequency and an external electrical resistance. We introduce three correlation metrics to quantitatively compare analytical prediction and experimental observation, including the normalized root mean square error, the correlation coefficient, and the weighted integrated factor. Analytical predictions are in an excellent agreement with experimental observations both mechanically and electrically. This study provides insightful guidelines for designing PVEH devices to reliably generate electric power under nonstationary random vibrations.

Structural dynamics effect on voltage generation from dual coupled cantilever based piezoelectric vibration energy harvester system

This article investigates the effect of structural dynamics on voltage generation from a novel dual coupled cantilever based piezoelectric vibration energy harvester (PVEH) system. Two non-destructive vibration techniques using the EMA and ODS analysis techniques have been integrated into the location selection scheme for enhancing vibration energy harvesting purpose. The location selection scheme is based on a measurement procedure on both harvester and its host structure to identify the optimal location. The results shows that the proposed cantilever PVEH is able to harvest high voltage in the high displacement region. An optimal location, (i.e. maximum vibration points/anti-nodal points) determined by the location selection scheme could yield 33.3% improvement in harvested voltage, as compared to baseline voltage. Meanwhile, if the piezoelectric plate is placed at any minimal vibration points or nodal point on the structure as determined by the location selection scheme, a significant reduction (>70%) in harvested voltage is observed.

Randomly-disordered-periodic-induced chaos in a piezoelectric vibration energy harvester system with fractional-order physical properties

The chaotic behavior of the piezoelectric vibration energy harvester (VEH) system with fractional order physical properties under randomly disordered periodic excitations is investigated. By using random Melnikov method, a mean square criterion is used to detect the necessary conditions for chaotic motion of this stochastic system. The results indicate that the increase of the noise intensity will result in the occurrence of chaos and the changes of the possible chaotic region in phase space, which first enlarging and then shrinking with a change in trend. The threshold of amplitude of randomly disordered periodic for the onset of chaos is determined by the numerical calculation via the largest Lyapunov exponent. The effects of noise intensity on chaos are also investigated through the largest Lyapunov exponent, phase portraits, Poincaré maps. At the same time, the effects of intensity of random frequency on the mean square voltage are further discussed, which show that the square voltage is in positive proportion to the size of the chaotic region. It is demonstrated that the essential changes of the dynamical behavior of the piezoelectric energy harvester system with fractional order physical properties will occur through changing the noise intensity, which can not only induce or suppress the onset of the chaos, but also raise or reduce the mean square voltage. Finally, the 0–1 test of responses is used to quantify the responses of VEH system, which further supports the effects of noise intensity on chaotic behavior of the system.

Melnikov-method-based broadband mechanism and necessary conditions of nonlinear rotating energy harvesting using piezoelectric beam

Nonlinearity can be used to enhance broadband rotating piezoelectric vibration energy harvesting, but how to construct a proper nonlinear rotating harvester is a challenging problem in engineering applications. This article presents a Melnikov-theory-based method to explore broadband mechanism and necessary conditions of nonlinear rotating piezoelectric vibration energy harvesting system. First, a perturbed state-space representation of nonlinear rotating energy harvesting system is built based on its dynamic model. It can be seen that bi-stability of the unperturbed nonlinear system is the physical basis of achieving broadband and low-frequency rotating energy harvesting. Second, the Melnikov function is defined to derive two necessary conditions of homoclinic bifurcation and chaotic motions. Then simulations are performed to identify the key parameters and their effects on the Melnikov conditions, including distance, rotating frequency, and excitations. It can be seen that homoclinic bifurcation and chaotic motions can occur in nonlinear rotating energy harvesting systems under single-frequency and broadband excitations. Finally, the experiments are carried out to validate the two necessary conditions. The results demonstrate that the proposed method can provide important guidelines for optimally designing nonlinear rotating piezoelectric energy harvesters in practice.

Maximum Performance of Piezoelectric Energy Harvesters When Coupled to Interface Circuits

This paper presents a complete optimization of a piezoelectric vibration energy harvesting system, including a piezoelectric transducer, a power conditioning circuit with full semiconductor device models, a battery and passive components. To the authors awareness, this is the first time and all of these elements have been integrated into one optimization. The optimization is done within a framework, which models the combined mechanical and electrical elements of a complete piezoelectric vibration energy harvesting system. To realize the optimization, an optimal electrical damping is achieved using a single-supply pre-biasing circuit with a buck converter to charge the battery. The model is implemented in MATLAB and verified in SPICE. The results of the full system model are used to find the mechanical and electrical system parameters required to maximize the power output. The model, therefore, yields the upper bound of the output power and the system effectiveness of complete piezoelectric energy harvesting systems and, hence, provides both a benchmark for assessing the effectiveness of existing harvesters and a framework to design the optimized harvesters. It is also shown that the increased acceleration does not always result in increased power generation as a larger damping force is required, forcing a geometry change of the harvester to avoid exceeding the piezoelectric breakdown voltage. Similarly, increasing available volume may not result in the increased power generation because of the difficulty of resonating the beam at certain frequencies whilst utilizing the entire volume. A maximum system effectiveness of 48% is shown to be achievable at 100 Hz for a 3.38-cm3 generator.