Electromagnetic Energy Harvesting Device Research Articles

Variable-Length Pendulum-Based Mechatronic Systems for Energy Harvesting: A Review of Dynamic Models

The ability to power low-power devices and sensors has drawn a great deal of interest to energy harvesting from ambient vibrations. The application of variable-length pendulum systems in conjunction with piezoelectric or electromagnetic energy-harvesting devices is examined in this thorough analysis. Because of their changeable length, such pendulums may effectively convert mechanical vibrations into electrical energy. This study covers these energy-harvesting systems’ basic theories, design concerns, modeling methods, and performance optimization strategies. This article reviews several studies that look at dynamic models, the effects of damping coefficients, device designs, and excitation parameters on energy output. The advantages and disadvantages of piezoelectric and electromagnetic coupling techniques are demonstrated by comparative research. This review also looks at technical advances and future research prospects in variable-length, pendulum-based energy harvesting. An expanded model for an energy harvester based on a variable-length pendulum derived from the modified, swinging Atwood machine is more specifically presented. This model’s numerical simulations, estimated current and voltage outputs, and produced power from the electromagnetic and piezoelectric devices integrated at various points in a 4-DOF variable-length pendulum model all indicate encouraging results. This necessitates extra study, changes, and optimizations to improve the usefulness of the proposed model. Finally, important dynamic models on developing variable-length, pendulum-based energy harvesters for usage in a range of applications to create sustainable energy are summarized.

Harvesting energy vibration derived from the rotational speed of a A 4-stroke engine

The utilization of vibration energy from a 4-stroke engine as a potential source of electrical energy. Previous studies have focused on analyzing the vibration characteristics and frequency response functions of the 4-stroke engine, but there is a lack of research on harnessing vibration energy as a source of electrical energy. Therefore, this research aims to fill this gap by developing a system to harness the vibration energy from the 4-stroke engine, making it a primary focus of the study. The method employed is an experimental study involving data collection using an FFT Analyzer and Matlab. The research results indicate the presence of several mode shapes in the 4-stroke piston motor. The energy harvesting device utilized is of the electromagnetic type. However, the research reveals that the utilization of vibrations from the 4-stroke piston motor as a source of electrical energy is still not efficient and requires further development. There are various mode shapes in the 4-stroke piston motor at different rotational speeds, but the electromagnetic energy harvesting device used is unable to generate significant electrical energy. Therefore, this research provides a foundation for conducting further research in utilizing the vibrations of a 4-stroke piston motor as a more efficient source of electrical energy

Research on pendulum-type tunable vibration energy harvesting

Sensors, as the most common electronic devices in electromechanical systems, are often scattered in huge numbers in the environment to be monitored. When the power of the sensor comes from batteries, the long-term continuous power supply and the replacement of the battery under severe working conditions are the main problems. Compared with other energy sources, vibration energy is more universal and stable, so it is often harvested and utilized by specific devices. Most of the traditional vibration energy harvesting devices have the disadvantage that the natural frequency cannot be tuned, which will lead to significant decline of energy harvesting efficiency when the environmental frequency changes. Although some energy harvesting devices are with tunable nature frequency, the linearity is relatively poor when tuning. In order to solve the problems above, a structural model of an electromagnetic energy harvesting device using motion of a pendulum rod is constructed. Natural frequency characteristics and electromagnetic field finite element simulation analysis of the model are carried out. An experimental platform of the device and a corresponding electric energy storage circuit are designed and built. Simulation and experimental results show that the natural frequency of the device can be tuned linearly in the range of 7 Hz–13.5 Hz. The maximum induced electromotive force that the device can output is 1.37 V and the maximum power is 521 mW. When the device is connected to the electric energy storage circuit, the device can output 3.4 V DC voltage. Compared with the traditional devices that can only harvest energy efficiently from a single vibration frequency, the advantage of this model is that its natural frequency can be adjusted to adapt to different ambient vibration frequencies and the linearity of tuning has been verified, which makes its energy harvesting efficiency relatively higher. The device model proposed in this paper would have potential application value in the field of vibration energy harvesting and wireless micro sensors power supply.

Tri-Band Rectenna Dedicated to UHF RFID, GSM-1800 and UMTS-2100 Frequency Bands

The omnipresence of connected objects leads to the quasi-permanent presence of electromagnetic waves from different sources in our environment. This article presents a new electromagnetic energy harvesting device, rectenna type, which offers the advantage of being versatile. Indeed, the proposed prototype is compatible with three frequency bands of radio standards widely deployed today (UHF RFID, GSM-1800, and UMTS-2100), and its performances remain good for low to very low ambient power levels as well as for different loads depending on the targeted application. The proposed solution is based on a tri-band antenna with very good efficiency and a bandwidth of at least 80 MHz for each of the operating frequencies. Moreover, the associated rectifier circuit is also tri-band and offers good performance in terms of RF-to-DC conversion efficiency for input levels varying in a rather wide range of power levels. The study is based on a design phase by simulation until the realization of prototypes and their experimental characterization. The designed rectenna is compared with solutions found in the literature.

Underwater Energy Harvesting to Extend Operation Time of Submersible Sensors.

A linear electromagnetic energy harvesting device for underwater applications, fabricated with a simple manufacturing process, was developed to operate with movement frequencies from 0.1 to 0.4 Hz. The generator has two coils, and the effect of the combination of the two coils was investigated. The experimental study has shown that the energy capture system was able to supply energy to several ocean sensors, producing 7.77 mJ per second with wave movements at 0.4 Hz. This study shows that this energy is enough to restore the energy used by the battery or the capacitor and continue supplying energy to the sensors used in the experimental work. For an ocean wave frequency of 0.4 Hz, the generator can supply power to 8 sensors or 48 sensors, depending on the energy consumed and its optimization.

Dynamic analysis and design of power management circuit of the nonlinear electromagnetic energy harvesting device for the automobile suspension

A nonlinear electromagnetic energy harvester (EMEH) for the automobile suspension is designed. The magnetic flux density and the magnet repulsive force of the mechanical model are determined by finite element analysis. The dynamic model of a quarter car with the nonlinear EMEH under random road excitation is established. The influence of structure parameters on output characteristics of the nonlinear EMEH is studied. In order to further improve the output power, effects of the road class, the car speed, and the load resistance are investigated in detail. Studies have revealed that the higher the road class and the larger the car speed are, the better output characteristics of the nonlinear EMEH become. In order to prove that the nonlinear magnet repulsive force can significantly improve the output power, output characteristics of the nonlinear EMEH and the linear EMEH are compared. Finally, the power management circuit matching with the nonlinear EMEH is designed, which can convert the unstable alternating voltage into the stable direct voltage, and directly supply power to electronic devices. There are two innovations in this paper. One is the introduction of the nonlinear magnet repulsive force and the amplification bar in the structural design. Another is to design the power management circuit of the high energy conversion efficiency, which is up to 74.3% for the car speed 25 m/s on the road of class C.

Review of Power Converter Impact of Electromagnetic Energy Harvesting Circuits and Devices for Autonomous Sensor Applications

The demand for power is increasing due to the rapid growth of the population. Therefore, energy harvesting (EH) from ambient sources has become popular. The reduction of power consumption in modern wireless systems provides a basis for the replacement of batteries with the electromagnetic energy harvesting (EMEH) approach. This study presents a general review of the EMEH techniques for autonomous sensor (ATS) applications. Electromagnetic devices show great potential when used to power such ATS technologies or convert mechanical energy to electrical energy. As its power source, this stage harvests ambient energy and features a self-starting and self-powered process without the use of batteries. Therefore, it consumes low power and is highly stable for harvesting energy from the environment with low ambient energy sources. The review highlights EMEH circuits, low power EMEH devices, power electronic converters, and controllers utilized in numerous applications, and described their impacts on energy conservation, benefits, and limitation. This study ultimately aims to suggest a smart, low-voltage electronic circuit for a low-power sensor that harvests electromagnetic energy. This review also focuses on various issues and suggestions of future EMEH for low power autonomous sensors.

Development and experimental validation of self-powered wireless vibration sensor node using vibration energy harvester

This paper deals with development of a self-powered solution for wireless vibration sensing. An autonomous operation of the proposed vibration sensor node is based on an electromagnetic energy harvesting device which converts kinetic energy of ambient mechanical vibration. Moreover, mechanical vibrations are monitored via electric signal from a piezoelectric patch and the measured signal is transmitted to the monitoring unit. The electromagnetic energy harvester is designed to provide enough power for a signal processing unit and a communication module, enabling the system to operate as a self-powered wireless vibration sensor node. Operation of this system was experimentally validated in laboratory environment and examples of vibration monitoring are presented. There is a significant restriction in terms of operation in resonance regime, where the generated power of the kinetic energy harvester is maximal and sufficient for limitless operation of the node. Main aim of this paper is to present a complex system which could be used in many engineering applications, such as aerospace, transportation, or civil structure monitoring.

Permanent magnet energy harvesting pedal based on compliant lever and energy storage structure

The rapid development of low-power electronic sensors and integrated circuits has made the energy supply module complex and costly to a greater extent. The traditional energy supply method is based on external wiring or built-in batteries, which gives rise to a series of problems such as high costs of installation and maintenance, and environmental pollution. Mini-type energy generators absorb the ambient energy to power wireless devices, which is a promising energy supplying method. This method has the advantage of low installation cost and battery-free maintenance. This study proposed a digital design of a Step-type electromagnetic energy harvesting device. Two design goals should be considered to make the energy generator work well. First, the pedal can drive the energy generator to generate electricity during the stepping and rebounding process. Second, the pedal should have a small pedaling displacement, so as not to affect the normal walking state of pedestrians. To achieve the above goals, this research designed a compliant lever structure with elastic energy storage function and displacement amplification function. The pseudo-rigid body model is used to conceptually design the flexible mechanism. The electromagnetic force of the iron core at different positions is calculated by simulation analysis and verified by experiments. Based on these results, this device can be used effectively as a monitoring system host node at the doorways of hospital wards.

A study on the optimal design and the performance evaluation of electromagnetic energy harvesting device for the rolling stock application

An electromagnetic energy harvesting device was studied based on the design parameters of an energy harvesting device for the power source of wireless sensors node on the rolling stock. The characteristics of the generated power by the energy harvesting device were tested using the laboratory equipment and a rolling stock (a high-speed train). First, a cantilever beam energy harvesting device, which allows for easy adjustment of the length according to the frequency and the power according to the cantilever beam materials, was researched. In addition, the new design for a practical resonant energy harvesting device for the railroad system was performed. To realize the performance of the practical resonant energy harvesting device, the generated power characteristics of the energy harvesting device were tested according to the moving displacement, the number of coil turns, and the initial coil displacement between the coil and magnet. The evaluation of the performance of the manufactured resonant energy harvesting device for the railroad system, which the parameters were determined based on the test results, was conducted under real driving conditions in the high-speed train, which was traveling at 300 km/h. Finally, this study analyzed whether the power generated could be applied to the wireless sensor nodes for the railroad system.

Dual-Rotor Electromagnetic-Based Energy Harvesting System for Smart Home Applications

This work presents the development of a dual-rotor rotational electromagnetic energy harvesting (EH) generator and its power management system (PMS). The electromagnetic harvester is driven mechanically by pushing or pulling a shaft. By doing so, energy can be harvested in both directions. The PMS steps up the ac voltage of the EH system and converts it into a useful dc one utilizing a maximum power point tracking (MPPT) concept. The PMS together with EH system are tested and the experimental results for the full system are presented. The EH device generates a maximum output energy of $100~\mu \text{J}$ with a maximum open circuit voltage of 0.7 V. The PMS achieves an efficiency of 70% while providing $350~\mu \text{A}$ at its output.

Experimental Analysis on the Transduction Coefficient of a Non-Linear Electromagnetic Energy Harvesting Device with Softening Stiffness

Nonlinear energy harvesting devices in the form of stiffness nonlinearity have emerged as among the effective solutions to overcome the performance limit of linear energy harvesting devices. However, up to now, researches on the nonlinear devices are only focusing on the ability to widen the bandwidth while the limit of employing linear transduction coefficient in a nonlinear system has yet to be heavily discussed. This paper investigates on the transduction coefficient for both linear and nonlinear systems of an electromagnetic energy harvesting device as a function of the excitation frequency. It is proven that the transduction coefficient of the nonlinear device is larger than its equivalent linear device, especially in the multi-stable solutions region. In common practice, the nonlinearity in the nonlinear system is considered weak, and its transduction coefficient is assumed to converge to the one produced by the linear system. The limits to which the transduction coefficient of a linear system can be employed on the nonlinear system were drawn based on the experimental analysis conducted on the proposed device. The device was designed to perform as a linear or nonlinear system, where the degree of nonlinearity was changed by varying the gap between the magnets. The limit of the transduction coefficient was determined from the analysis of the harmonic ratio. The results show that the linear transduction coefficient is valid to be employed to the nonlinear system when the harmonic ratio is less than five per cent at the multi-stable solutions region.

Electromagnetic Vibrational Energy Harvester With Microfabricated Springs and Flexible Coils

In this article, an electromagnetic vibrational energy harvester (EVEH) device has been designed and fabricated based on the hybrid microelectromechanical system and flexible circuit technology. The designed EVEH is composed of a disc magnet suspended by four microfabricated silicon springs above a stack of high-density flexible planar coils. At a sinusoidal acceleration with a peak-to-peak amplitude of 1 g, an output peak-to-peak voltage of 208.3 mV, and an output power of 10.5 μW are measured at the resonant frequency of 143 Hz. At an elevated acceleration of 7 g, a maximum output peak-to-peak voltage of 333.1 mV is realized with an increased magnet-coil distance of 0.65 mm.

Body-Integrated Self-Powered System for Wearable and Implantable Applications.

The human body has an abundance of available energy from the mechanical movements of walking, jumping, and running. Many devices such as electromagnetic, piezoelectric, and triboelectric energy harvesting devices have been demonstrated to convert body mechanical energy into electricity, which can be used to power various wearable and implantable electronics. However, the complicated structure, high cost of production/maintenance, and limitation of wearing and implantation sites restrict the development and commercialization of the body energy harvesters. Here, we present a body-integrated self-powered system (BISS) that is a succinct, highly efficient, and cost-effective method to scavenge energy from human motions. The biomechanical energy of the moving human body can be harvested through a piece of electrode attached to skin. The basic principle of the BISS is inspired by the comprehensive effect of triboelectrification between soles and floor and electrification of the human body. We have proven the feasibility of powering electronics using the BISS in vitro and in vivo. Our investigation of the BISS exhibits an extraordinarily simple, economical, and applicable strategy to harvest energy from human body movements, which has great potential for practical applications of self-powered wearable and implantable electronics in the future.

A miniaturized electromagnetic energy harvester with volt-level output based on stacked flexible coils

The bottleneck of the miniaturized electromagnetic vibration energy harvester (EVEH) device is the limited output voltage and power. Commonly reported mV-level AC output of the EVEHs cannot be rectified and used. In this work, we report a cost-effective EVEH device based on batch-fabricated flexible springs and coils. At an acceleration of ±1 g peak-to-peak amplitude (±9.8 m s−2), a maximum output peak-to-peak voltage of 1.57 V and an output power of 91.8 μW are measured, at a frequency of 66 Hz. The output voltage of the EVEH is successfully rectified, amplified (passively) and used to charge a supercapacitor.

A new electromagnetic vibrational energy harvesting device for swaying cables

An original vibrational energy harvesting device with regard to the vibrational performance of far-end cables was designed under the condition that no power can be supplied to the far end of freight cableways in transmission and distribution projects. The device was designed to have a Y-shaped radial gear-rack structure. The random vibrations of the cable are converted into three one-way rotary motions of a Y-shaped device terminal using a Y-shaped rack unit and one-way gear-rack units. The device then harvests the electric energy through a super-capacitor and supplies power to equipment in areas out of the reach of the power supply along the cableway. An analysis and dynamic simulation of the Y-shaped rack unit and one-way gear-rack units demonstrate that the Y-shaped layout of the device adapts well to the random vibration of the cable. The device was proven to have successfully harvested the vibrational energy of the cable in several directions on its radial plane, showing good prospects in supplying power to far-end wireless surveillance equipment for freight cableways in remote mountainous areas.

An electromagnetic rotational energy harvester using sprung eccentric rotor, driven by pseudo-walking motion

In this work, an electromagnetic energy harvesting device using a sprung eccentric rotor has been designed, optimized and characterized to harvest power from pseudo-walking signals (a single frequency sinusoidal signal derived from motion of a driven pendulum that approximates the swing of a human-arm during walking). Our analysis shows that a rotor with an eccentric mass suspended by a torsional spring enhances the mechanical energy captured from low-frequency excitations (e.g., those produced during human walking, running/jogging). An electromagnetic transducer in the sprung eccentric rotor structure converts the captured mechanical energy into electrical energy. An electromechanical dynamic model of a sprung eccentric rotor has been developed and an optimization routine was performed to maximize output power under pseudo-walking excitation. The structure of the electromagnetic transducer was refined using Finite Element Analysis (FEA) simulations. A prototype energy harvester was fabricated and tested in a pseudo wrist-worn situation (by mounting on a mechanical swing-arm) to mimic the low-frequency excitation produced during human walking. A series of pseudo-walking motions was created by varying the swing profile (angle and frequency). The prototype with optimal spring stiffness generates a maximum 61.3 μW average power at ±25° rotational amplitude and 1 Hz frequency which is about 6-times higher than its unsprung counterpart under same excitation condition. The experimental results are in good agreement with the simulation results.

Modeling and Experiment of Electromagnetic Energy Harvester System by Using Dual Moving Mechanical Systems at Low Frequency Range.

This paper presented a concept of single degree of freedom (SDOF) electromagnetic vibration energy harvester device. This technique enable system to operate at wideband frequency range, low frequency and has multi-resonance frequencies. Each mechanical system operates at difference frequency where each system is attached with electromagnetic transducer components. the device is developed based on the parameter factors of vibration transmissibility from external vibration sources into the device through mathematical modelling. A prototype was tested by using vibration exciter and normal human walking. the fabricated device had showed multi-resonant behavior at 4.26 and 8.34 Hz during test. From experiment results, they have showed capability to operate at wide bandwidth frequency from 1.9 until 18.5 Hz at a periodic excitation of 0.04 g. the highest amount of rms voltage that has been produced about 108 mV with a maximum 78 µW average power across the 150 Ω load resistance. So, it has proven the dual-moving mechanical concept with low damping value in system has increased the operating bandwidth frequency and also increased the amount of output voltage from device.

Karman Vortex Creation Using Cylinder for Flutter Energy Harvester Device.

This study presents the creation of a Karman vortex for a fluttering electromagnetic energy harvester device using a cylinder. The effects of two parameters, which are the diameter and the position of the cylinder, were investigated on the Karman vortex profile and the amplitude of the fluttering belt, respectively. A simulation was conducted to determine the effect of the creation of the Karman vortex, and an experiment was performed to identify influence of the position of the cylinder on the fluttering belt amplitude. The results demonstrated that vortex-induced vibration occurred at the frequency of the first natural mode for the belt at 3 cm and 10 cm for the diameter and position of the cylinder, respectively. Under such configuration, an electromagnetic energy harvester was attached and vibrated via the fluttering belt inside the turbulent boundary layers. This vibration provides a measured output voltage and can be used in wireless sensors.

A batch-fabricated electromagnetic energy harvester based on flex-rigid structures

In this paper, an electromagnetic energy harvester device is designed and fabricated, based on a rigid-flex structure. The device has a FR4 proof mass carrying a bi-layer copper planar coil, suspended by four soft polyimide springs over a disc permanent magnet. The device is batch-fabricated with a standard production process of rigid-flex Printed Circuit Board (PCB). The assembled energy harvester is excited by sinusoidal accelerations and characterized dynamically. At an acceleration of 2g peak-to-peak amplitude (±1g, ±9.8m/s2), a maximum output peak-to-peak voltage of 9.85mV and an output power of 1.24μW are measured, at the device’s resonance frequency of 155Hz. With an elevated acceleration of 10g (±5g), a maximum output peak-to-peak voltage of 22.58mV and an output power of 7.21μW are achieved.