Magnetostrictive Energy Harvester Research Articles

Nonlinear Model for Magnetostrictive Vibration Energy Harvester Considering Dynamic Forces

Nonlinear Model for Magnetostrictive Vibration Energy Harvester Considering Dynamic Forces

Design and analysis of magnetostrictive two-dimensional kinetic energy harvester

Conventional energy harvesters often require high ambient vibration frequencies and can only capture vibration energy in a single direction. To address these issues, this paper designs a magnetostrictive two-dimensional kinetic energy harvester placed under the floor and capable of capturing energy in both vertical and horizontal directions. In order to achieve higher electrical power output at low-frequency input forces, a two-stage force amplification mechanism is designed to amplify the walking kinetic energy of pedestrians and the main parameters of this structure are analyzed and optimized. On the other hand, by constructing different forms of bias magnetic field, the influence of bias magnetic field on the deflection and motion of the internal magnetic domain of Terfenol-D is systematically studied, and the best bias form that can make the material shows the strongest magnetization characteristics is determined. Next, a prototype harvester was built, and an experimental vibration system was set up to test and analyze the output characteristics of the harvester comprehensively. The experimental results show that the harvester produces 21.2 mW of peak output power under sinusoidal excitation at an operating frequency of 4 Hz. Under random excitation, a peak output voltage of 2.64 V and 170 mW peak power was obtained. Under actual pedestrian walking tests, 17.62 mW peak output power is obtained to power low-power devices. The study’s results provide preliminary evidence that the designed magnetostrictive energy harvester can stably harvest kinetic energy from pedestrian walking.

Characterization of magnetostrictive bi-stable rotational vibration energy harvester with integrated centrifugal effect

Rotational machinery is a common presence in dust still production, and the occurrence of operational failures in components like engines and turbine blades necessitates effective measures. To solve this challenge, remote structural health monitoring using energy harvesting and wireless sensors has been widely employed to realize self-powered sensing. This study proposes a magnet-induced bi-stable rotational energy harvester (REH), which utilizes the centrifugal effect to broaden the effective frequency bandwidth, enabling efficient energy harvesting in complex environments. A comprehensive mathematical model has been established to facilitate the dynamic characteristics of the bi-stable system, taking into account the centrifugal effect. The theoretical results demonstrate that the gap distance of magnetic configuration has great effects on the bi-stable system. Additionally, the centrifugal effect decided by the centrifugal radius and rotational speeds also affects the stable high-energy orbit oscillations. Furthermore, experimental results indicate that the proposed REH can effectively operate within the frequency range of 230–290 rpm, with a maximum RMS voltage of 780 mV and corresponding power of 4.35 mW. These findings validate the performance of the bi-stable magnetostrictive REH with the centrifugal effect and indicate its potential to effectively address the power supply challenges for wireless sensors. Overall, this study presents a promising solution for enhancing the energy harvesting performance of REH and also provides insights into the design of high-efficiency REH by magnet-induced nonlinearity and the centrifugal effect.

Study of a magnetostrictive energy harvester for harvesting transient shock vibration

Study of a magnetostrictive energy harvester for harvesting transient shock vibration

Modeling and efficiency maximization of magnetostrictive energy harvester under free vibration

Vibration energy harvesting is becoming increasingly attractive in line with the development of wireless sensor technologies. Magnetostrictive materials inherently exhibit high mechanical strength and are thus suitable for various applications and mass manufacturing of energy harvesting devices. Many studies have been conducted to increase the output power of harvesters, and some utilized analytical methods. However, the optimization methods often take into account only the resonant frequency of the system under forced vibration. These models can produce correct predictions only when steady-state harmonic excitation inputs are considered.In this study, we propose the modeling and optimization method for a cantilever-type magnetostrictive harvester under free vibration. The cantilever has a double-beam structure composed of two parallel Fe-Ga beams with pickup coils. In the modeling, the shape function of the cantilever-type magnetostrictive energy harvester was derived based on the continuity of the internal force and magnetic flux. Hamilton’s principle for an electromagnetic-mechanically coupled system was derived from the virtual work principle. The equation of motion, magnetic circuit equation, and electric circuit equation of the system were respectively derived from the corresponding Euler–Lagrange equations. The harvestable energy of the magnetostrictive energy harvester was calculated by using the symmetric property of eigenvalues. In the efficiency maximization of the harvestable energy, we found that the optimal solution differs depending on the type of given energy. The optimal parameters to maximize the energy efficiency to potential energy and kinetic energy are respectively derived in the form of algebraic solutions. Experimental validation was conducted by measuring the energy harvesting efficiency at different loads.

Design and Optimization of a Boost Interface for Magnetostrictive Energy Harvesting

Magnetostrictive alloys are very promising for Vibration Energy Harvesting applications to supply power to Wireless Sensor Network (WSN) and Internet of Things (IoT) devices, especially because of their intrinsic robustness. Typically, vibration energy sources are random in nature, usually providing exploitable voltages much lower than the electronic standards 1.6, 3.3 and 5 V. Therefore, a Power Electronic Interface (PEI) is needed to improve the conversion to DC output voltage from AC input over a wide range of frequencies and amplitudes. Very few or no conversion techniques are available for magnetostrictive devices, although several have been presented over the years for other smart materials, such as piezoelectrics. For example, hybrid buck–boost converters for piezoelectrics use one or more external inductors with a high-frequency switching technique. However, because of the intrinsic nature of harvesters based on magnetostrictive materials, such energy conversion techniques are proved to be neither efficient nor applicable. An improved AC–DC boost converter seems very promising for our purpose instead. The key feature is represented by the direct exploitation of the active harvester coil as a storage element of the boost circuit, without using other passive inductors as in other switching methods. Experimental tests of such a converter, driven with a real-time operating Arduino controller to detect the polarity of the input voltage, are presented with the aim to assess the potentiality of the scheme with both sinusoidal and impulse-like inputs. Simulations have been performed with LTspice, and the performance and efficiency have been compared with other energy conversion techniques.

Harvesting electricity from random vibrations via a nonlinear energy sink

Integration of a vibration absorber and an energy harvester is a promising approach to achieve simultaneously vibration reductions and vibratory energy harvesting. The present work investigates random responses of a nonlinear energy sink (NES) combined with a giant magnetostrictive energy harvester (GMEH). When a structure is modeled as a one-degree-of-freedom oscillator subjected to a random excitation, the structure with the integrated NES-GMEH is governed by two simultaneous nonlinear stochastic differential equations coupled with a nonlinear algebraic equation. The Ferrari formula is applied to decouple the algebraic equations from the stochastic differential-algebraic equations. The resulting stochastic algebraic differential equations are transformed into the steady Fokker-Planck-Kolmogorov equations. A fourth finite difference scheme is used to solve numerically the FPK equations. The FPK equations based solutions are qualitatively verified via Monte Carlo simulations. The parametric effects on vibration suppression and electricity production are examined, where the electricity is indicated by the square expectations of voltage and power. The responses of the structure, the structure with the NES only and the structure with both NES-GMEH are compared under the same Gaussian white noise and system parameters. It is found that the integrated NES-GMEH system achieves the best vibration suppression. It is demonstrated that a properly designed NES-GMEH device can simultaneously suppress vibration and produce electricity under Gaussian white noise excitations.

Validation of thermodynamic magneto-mechanical finite-element model on cantilever-beam type magnetostrictive energy harvester

This paper presents the validation of a thermodynamic magneto-mechanical model to analyze a galfenol based cantilever beam type energy harvesting device. As compared to some earlier modeling approaches that were tested only on specific harvester geometries, the thermodynamic model has already been validated on rod-type harvesters and is now shown to be suitable for analyzing also beam-type devices. Moreover, the paper discusses the influence of magnetostriction upon resonant frequency. The thermodynamic model is implemented in a 3D finite element solver using COMSOL Multiphysics software. This allows optimizing the device design by tuning the geometric parameters and magnetic bias under available operating conditions (amplitude and frequency of vibrations) easily and efficiently. A unimorph cantilever beam type prototype harvester device consisting of a galfenol beam bonded to an aluminum substrate is constructed for validating the model. Simulated and measured results are compared at base excitation amplitudes of 0.5 to 2 g under varying vibration frequencies. The results show that the maximum induced voltage is obtained at the resonant frequency which decreases slightly with an increase in the vibration amplitude. Furthermore, it is shown that the resonant frequency decreases from 201 Hz to 187 Hz at 1 g base acceleration when the magnetic bias is removed. The comparison of measured and simulated results show that the model can accurately predict the resonant frequency with a relative error of less than 2 %, validating the modeling approach. The model can also reasonably determine the open circuit voltage with some discrepancies at large vibration amplitudes.

Design and Characteristic Analysis of Magnetostrictive Vibration Harvester with Double-Stage Rhombus Amplification Mechanism

Vibration energy harvesting is a new alternative to lithium battery power for low-power devices, attempting to recover wasted or lost vibration energy to generate electricity. Magnetostrictive-based energy harvesting exploits the coupling properties of the Villari and Faraday electromagnetic induction effects to achieve mechanical–magnetic–electric energy conversion. In order to better apply to the actual vibration environment, such as buses, and improve the ability to capture low-frequency vibration energy, a double-stage rhombus vibration energy harvesting device, based on Terfenol-D rods, was developed. By establishing an analytical model of the force amplification ratio of the harvesting device, the design is optimized using the Single-Objective Genetic Algorithm, and the safety and pre-magnetization layout methods are analyzed by Finite Element Analysis. The output characteristics of the prototype, including the output voltage frequency response under low-frequency regular excitation and random excitation, the effect of external resistance, and the vibration energy capture performance under random excitation, are investigated in detail through experiments. The results of the experiments showed that the peak output power of the fabricated prototype was 1.056 mW at 30 Hz operating frequency, the energy harvesting capability reached 41.4 μW/N, and the peak open circuit voltage and output power were 2.92 V and 266 mW, respectively, under random excitation. Practical application test results showed that the peak voltage generated was 1.06–1.51 V when the excitation level was 2.2–4.9 m/s2. The comparative study indicates that the output performance of the proposed double-stage rhombus magnetostrictive vibration energy harvesting system is a great improvement over the proposals of existing literature.

Magnetostrictive biomechanical energy harvester with a hybrid force amplifier

Vibrating energy harvesters, capable of converting mechanical energy into electrical energy, have attracted unprecedented interest in both academia and industry because of their great potential for harvesting energy induced by human activity and energy around the body, and to drive low-power wearable biosensors and electronics, micro-robots, and implantable biomedical devices. In this paper, based on the magnetostrictive inverse effect, we propose a magnetostrictive vibration harvester using Terfenol-D, which generates electrical energy when subjected to human movement. A hybrid force amplification frame is integrated in this harvester to amplify weak biological movements. The detailed mathematical model of the multi-stage force amplification process is established, the hybrid force amplifier is also designed in detail, and its structural dimensions are optimized. The position and form of the bias magnetic field arrangement based on the Terfenol-D harvester is systematically analyzed. The experiment shows that 4.13 V peak voltage and 426.4 mW peak power are generated when the harvester is fully compressed. The output power is 213.16 mW and 371.43 mW at an average acceleration of 2.5 g for slow walking and 4 g for jogging, respectively. The results of this study suggest that the combination of rod Terfenol-D and force amplification mechanisms can be used to design bio-vibrational energy harvester with excellent performance, which is especially suitable for self-powered wearable electronic devices.

Nonlinear Dynamic Analysis of Hybrid Piezoelectric-Magnetostrictive Energy-Harvesting Systems

To progress the proficiency and broaden the action bandwidth of vibration energy harvesters, this paper presents a cantilever piezoelectric-magnetostrictive bistable hybrid energy harvester with a dynamic magnifier. The hybrid energy-harvesting system comprises two vibration degrees of freedom and two electrical degrees of freedom. It consists of a composite cantilever beam made of three layers, in which the magnetostrictive and piezoelectric layers are attached to the top and bottom of the base layer. The electromechanically coupled vibration equations of the whole hybrid structure were established with the lumped-parameter model while taking into account the magnetic interaction of two magnets. The nonlinear frequency-response of vibrations for the hybrid harvester is calculated using the harmonic balance method, and the model has been validated by literature. The time response and phase portraits of oscillation for the cantilever harvester and its performance in generating electrical power under different magnet distances, dynamic magnifier features, and excitation levels are analyzed. Numerical results have shown that the hybrid structure can harvest additional electrical power and operates at larger bandwidth than routine bistable piezoelectric or magnetostrictive energy harvesters.

Erratum: "Working characteristics of a magnetostrictive vibration energy harvester for rotating car wheels" [Rev. Sci. Instrum. 93, 055001 (2022)

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Performance of Fe–Ga alloy rotational vibration energy harvester with centrifugal softening

With the development of vibration energy harvesting, sensor nodes for wireless monitoring are being increasingly powered by harvesting vibrations in rotating environments such as car tires and fan blades. Considering the diverse installation positions of vibration energy harvesters on rotating carriers, the centrifugal forces of the cantilever beams exhibit remarkable differences during rotation. Crucial factors for the performance of vibration energy harvesting include the deformation of the harvester cantilever beam, which is affected by the centrifugal force, and the influence of the pre-magnetization field on the Villari effect of specific alloys. We propose a rotational vibration energy harvester based on an Fe–Ga alloy and establish a mathematical model for magnetostrictive vibration energy harvesting by leveraging centrifugal softening. In addition, we perform a systematic theoretical analysis of the factors influencing the harvester performance considering centrifugal softening, rotation radius, and arrangement of the pre-magnetization field. The theoretical findings are verified on a prototype, and the system characteristics are investigated experimentally. The maximum output voltage reaches 3.36 V, and the energy harvesting efficiency reaches 22.86% when the harvester undergoes rotation at 330 r min−1. Moreover, the harvester is applied in a low-power temperature sensor for real-time temperature monitoring, indicating the validity and applicability of the proposed rotational vibration energy harvester. The results demonstrate that an appropriate use of the centrifugal softening and the pre-magnetization field can enhance the energy harvesting efficiency of a harvester operating at a low rotational frequency.

Working characteristics of a magnetostrictive vibration energy harvester for rotating car wheels.

The practice of harvesting vibration energy from machine tools, windmill blades, etc., and converting it into electric energy to power low-power electronic circuits has attracted wide attention from experts and scholars. Abundant vibrations that exist in the moving vehicle can be harvested to power sensors in tire pressure monitoring. In this paper, for the first time, a device is proposed to harvest the rotational vibration energy with the iron-gallium alloy (magnetostrictive material) as the core material. Such a device utilizes the coupling characteristics of Villarreal effect and Faraday electromagnetic effect to convert the vibration energy generated by the moving vehicle into electric energy. Upon completion of the design of the magnetostrictive rotational vibration energy harvester, the influence law of key factors, including substrate material, substrate size, and pre-magnetization field arrangement on the harvesting capability of the device, was studied in detail through experiments. An electric motor and vibration exciter were used to apply varied excitation forms to the harvester, and the output patterns of the harvester under conditions of wheel rotation, road bumps, and random vibration were fully analyzed. In addition, the correlation between the deformation of the cantilever beam and harvester performance was also investigated. The results have shown that at the acceleration of 9.6 g and the rotational speed of 90 r/min, the harvester can reach the output voltage of 1.22 V. Consequently, it demonstrates the feasibility of employing the magnetostrictive harvester to gather rotational vibration energy and provides theoretical guidance for further and deeper research on the harvester.

Development of a simple resonance frequency tuning method for magnetostrictive vibration energy harvesters

A fine-tuning method of the resonance frequency for a magnetostrictive vibration energy harvester by changing the magnetization state, namely using the ΔE effect of Young’s modulus, is proposed. Adjusting magnetization strength by changing the distance between the magnet for magnetization and the magnetostrictive vibration energy harvester in ten-millimeters revealed to tune the resonance frequency in 0.1 Hz order. A plot of the resonant frequency against the change in the flux density on the magnetostrictive material showed good agreement with a quadratic function approximation. A magnetostrictive vibration energy harvester tuned using this fine-tuning method could generate electricity stably for eleven days, suggesting the possibility of this fine-tuning method for long-term use.

Small-signal modeling and optimal operating condition of magnetostrictive energy harvester

Magnetostrictive energy harvesting has drawn attention in recent years for its high energy conversion efficiency and environmental durability. Magnetostrictive harvesters are mainly composed of giant magnetostrictive material, a magnetic circuit, and an electric circuit, which involves complex mechanical-electromagnetic coupled problems. Therefore, in many studies, the analysis of such device was implemented by finite element method. However, numerical calculation generally requires a great deal of time and does not provide adequate physical understanding of the effect of the design parameters on the harvester characteristics.In many previous studies, magnetostrictive harvesters have been operated under a small-signal vibration imposed over a constant prestress and magnetic bias. In such operating conditions, linearized small-signal models can be used to derive important analytical expressions for the harvester characteristics and their dependency on the design parameters. This paper presents the linearized modeling of a magnetostrictive energy harvester using linearized constitutive equations. The energy loss due to eddy currents is also considered for high-frequency application. The influence of parameter variation on the output power is investigated from the algebraically obtained output power, and the existence of an optimal value in resistance and capacitance of the electric circuit is discussed. These optimal design parameters are also presented in form of an algebraic solution. The obtained output power is finally proven to fit with experimental results when an appropriate permeability and magnetostrictive constant are given.

Magnetostrictive Materials and Energy Harvesting for Structural Health Monitoring Applications

Wireless sensors to monitor the state of the health of a civil structure could be widely adopted as a prompt and automatic solution to safeguard the cultural heritage and to guarantee safety. Nowadays, sensors are supplied by the electric grid or batteries, but in both cases some issues can occur. Batteries need to be recharged or replaced, thus increasing the operating cost of maintenance. The Energy Harvesting concerns with those actions focused on the exploitation of low-power, but widespread available, ambient energy sources, which otherwise would be normally wasted. In particular, the harvesting of vibrational kinetic energy could be a valid solution to the abovementioned problems, because of its large presence due to the anthropic activities and because it may overcome the strict rules to which historical sites often have to obey. Here a kinetic energy harvesting device based on magnetostrictives rods is presented. Its behavior is experimentally verified and discussed.

Magnetostrictive iron–gallium alloy harvester with efficient two-mode AC–DC converting technology for effective vibration energy harvesting

A magnetostrictive vibration energy harvester based on an iron–gallium alloy composite cantilever beam is developed, and its capability is optimized from the aspects of bias magnetic field and the number of active layers. To solve the issue of low and irregular output voltage, it designs a converter suitable for a low-power harvester to make full use of the generated electric energy. A set of AC–DC converters with two working modes is designed by using the multiple voltage rectification method, which is able to directly drive low power load or store energy to supply power to higher power load. Through theoretical simulation and experiment, the converter’s characteristics, such as rectifier and filter characteristics, energy storage, and release process are systematically studied and tested. 1 V AC output voltage of the harvester is able to be converted into 5 V DC voltage after being processed by the converter. The proposed harvester provides an excellent vibration harvesting capacity that the AC normalized power density (power density per volume and acceleration) reaches 7.4 mW/(cm3/g). The harvesting system with the two-mode converter has achieved a high normalized DC output power vs AC input voltage of 630 µW/V. We have applied the harvester and converter for a low power electronic meter, which can work normally and display the time, temperature, and humidity in the laboratory. In addition, we have also applied the harvesting system for a higher power (1.2 W) electric fan with a universal serial bus (USB) port. After battery charging and IP5306 voltage boosting, the harvester meets the normal operation requirements of an electric fan with a USB port and it is able to operate normally.

Notice of Violation of IEEE Publication Principles: Design and Development of Magnetostrictive Low Power DC Generator and Vibration Sensor

Notice of Violation of IEEE Publication Principles by Soumyabrata Patra in IEEE Sensors Journal, Vol. 20, No. 12, June 15, 2020 After careful and considered review of the content and authorship of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE’s Publication Principles. This paper contains significant portions of original text from the paper cited below. The original text was copied without attribution (including appropriate references to the original author(s) and/or paper title) and without permission. Performance of a Modified Magnetostrictive Energy Harvester in Mechanical Vibration by Subhasish Dey, Debabrata Roy, Soumyabrata Patra, Tapan Santra, in Heliyon, Vol 5, Issue 1, January 2019 Billions of off line powered smart things with embedded intelligence, such as sensors, actuators, and connectivity will support the rapid growth of IoT in the near future. The significant impact on worldwide energy consumption from these always-connected products has driven the need for compact, highly efficient off line power converters with ultra-low standby power consumption. This paper developed a novel Magnetostrictive energy harvester (MEH) with a power electronics converter for battery-free IoT applications. The developed energy harvester using Fe-Ga alloy (7×2×42 mm 3 ) as a Magnetostrictive material is able to generate peak to peak voltage around 21.6 Vat a vibration frequency of 29 Hz with the efficiency of 49% yields an average power of 51.23 mW. Such MEH output cannot be directly used to power IoT devices as it contains harmonic. This paper proposed two prototypes, MEH as a vibration sensor with sensitivity around 55 V.s/m (volt/(meter/second)) and as a DC power source for IoT devices, which can able to provide 10 V DC at 44.4 mWpower.

Gathering energy from ultra-low-frequency human walking using a double-frequency up-conversion harvester in public squares

Conventional human walking energy harvesters suffer from low-frequency problems. A double-frequency up-conversion magnetostrictive energy harvester was proposed, analyzed, fabricated, and tested. The harvester is mainly composed of a gear rack and a multi-leaf cam. The rack acts as the first frequency up-conversion mechanism for low-frequency walking. The multi-leaf cam carries out the second frequency up-conversion operation. After the two steps, the low walking frequency is increased. A theoretical analysis of the energy harvester was conducted to find factors that influence its performance. A standard concrete block was proposed, which made the application of the energy harvester easy and fast. The energy harvester was fabricated and experiments were carried out. The ratio of the frequency up-conversion mechanism was 8.13. The maximum output voltage and output power of the harvester were 10.06 V (peak-to-peak) and 31.3 mW, respectively. The harvested energy could light up 100 light-emitting diodes (LEDs) at the same time. It could also power an electronic clock normally for more than 90 min. The proposed energy harvester can be applied for gathering low-frequency human walking energy in public squares.