Magnetic Energy Harvester Research Articles

Enhanced Broadband Tri-Stable Energy Harvesting System by Adapting Potential Energy – Experimental Study

Abstract This paper presents the process optimization of some key parameters, such as the size of the air gap and distance between fixed neodymium magnets to enhance the vibration-based energy harvesting effect in the tri-stable energy harvesting systems and the improved tri-stable energy harvesting system being the proposed solution under weak excitation. In order to do it, firstly the distributed parameters model of the magnetic coupling energy harvesting system, including macro fiber composites of the 8514 P2 with a homogenous material in the piezoelectric fiber layer and nonlinear magnetic force, was determined. The performed numerical analysis of the conventional and the improved tri-stable energy harvesting system indicated that introducing an additional magnet to the tri-stable system leads to the shallowing of the depth of a potential well by decreasing the air gap between magnets and consequently generating higher power output and improving the effectiveness of the proposed improved tri-stable energy harvesting system. Experiments carried out on the laboratory stand allowed us to verify the numerical results as well as determine the optimal parameters of the magnetic coupling system. Due to it, the effectiveness of the proposed system versus the conventional tri-stable energy harvesting system is most enhanced.

Nonlinear Analysis and Closed-Form Solution for Overhead Line Magnetic Energy Harvester Behavior

Recently, much attention has been given to the development of various energy harvesting technologies to power remote electronic sensors, data loggers, and communicators that can be installed on smart grid systems. Magnetic energy harvesting is, perhaps, the most straightforward way to capture a significant amount of power from a current-carrying overhead line. Since the harvester is expected to have a small size, the high currents of the distribution system easily saturate its magnetic core. As a result, the operation of the magnetic harvester is highly nonlinear and makes precise analytical modeling difficult. The operation of an overhead line magnetic energy harvester (OLMEH) generating significant DC power output into a constant voltage load was investigated in this paper. The analysis method was based on the Froelich equation to analytically model the nonlinearity of the core’s BH characteristic. The main findings of this piecewise nonlinear analysis include a closed-form solution that accounts for both the core and rectifiers’ nonlinearities and provides an accurate prediction of OLMEH transfer window length, output current, and harvested power. Continuous and discontinuous operational modes are identified and the mode transition boundary is obtained quantitatively. The theoretical investigation was concluded by comparison with a computer simulation and also verified by the experimental results of a laboratory prototype harvester. A good agreement was found.

On the Maximum Power of Passive Magnetic Energy Harvesters Feeding Constant Voltage Loads Under High Primary Currents

On the Maximum Power of Passive Magnetic Energy Harvesters Feeding Constant Voltage Loads Under High Primary Currents

High Output, Biocompatible, Fully Flexible Fiber‐Based Magneto‐Mechano‐Electric Generator for Standalone‐Powered Electronics

AbstractHarvesting magnetic noise fields around power cables emerges as an attractive approach due to its potential as a renewable and ubiquitous energy source for powering wireless sensor networks (WSNs) in IoT applications, miniature electronics, and implantable medical devices. Flexible polymer‐based magneto‐mechano‐electric (MME) generators gain attention for their effectiveness in magnetic energy harvesting owing to their durability and flexibility. In this study, a lead‐free, flexible MME generator is developed by using Polyvinylidene fluoride (PVDF)‐Aluminium nitride (AlN)‐nanofiber composites fabricated via electrospinning with different AlN compositions and integrated with a magnetostrictive Metglas layer that offers self‐bias characteristics. The MME generator is modeled using COMSOL Multiphysics to analyze the magnetic flux density distribution over the Metglas surface and the piezoelectric effect of the nanofiber composites, with the simulation results aligning well with the experimental data. The optimized, flexible MME generator, incorporating 15 wt.% of AlN in the PVDF/Metglas composite, achieves an open‐circuit voltage of 18.5 V and a power density of 0.93 mW‐cm−3 when exposed to an Alternating Current (AC) magnetic noise field of 6 Oe at a resonance frequency of 50 Hz. The generated power is sufficient to operate LEDs and sensor. This newly developed lead‐free, flexible MME generator shows significant promise for advanced applications in self‐powered WSNs.

Design and Autonomy Evaluation of a Power Supply for Long Range IoT Devices Using Magnetic Field Harvested Energy from High Current

This study introduces a circuit designed to enhance energy conversion and storage, facilitating autonomous and sustainable operation from harvested magnetic energy in IoT devices. Through comprehensive experimentation and analysis, the circuit’s performance and reliability were assessed, showcasing its potential to provide a dependable power supply to IoT networks. Furthermore, various scenarios with different operation cycles and component combinations were simulated to validate the circuit’s potential. The findings indicate that integrating strategies such as energy redundancy using supercapacitors and magnetic field energy harvesting can be effective without the need for batteries or optimization circuits. The autonomy tests and predictions indicate that the system can go several days even without the total interruption on the energy source.

A Maximum-Power-Point Tracking Method Based on Constant Conduction Time Control With Constant Voltage Output for Magnetic Field Energy Harvesters in the Saturated Region

A Maximum-Power-Point Tracking Method Based on Constant Conduction Time Control With Constant Voltage Output for Magnetic Field Energy Harvesters in the Saturated Region

Magnetic transfer piezoelectric wind energy harvester with dual vibration mode conversion

Wind-induced vibration piezoelectric energy harvesters have garnered significant interest in recent years as a means to power autonomous wireless sensor systems. A magnetic transfer piezoelectric wind energy harvester (MT-PWEH) is proposed and its durability, power generation performance and environmental adaptability are improved utilizing dual mode conversion. This MT-PWEH incorporated a downstream rectangular baffle, which facilitated the transition of the hollow cylinder from a traditional single vortex-induced vibration to a coupled vibration involving both vortex-induced vibration and galloping (i.e., the first vibration mode conversion). Besides, the vibration direction of the hollow cylinder was perpendicular to the vibration direction of the transducer, which achieved the purpose of limiting the amplitude (i.e., the second vibration mode conversion). The feasibility of MT-PWEH was confirmed through theoretical analysis, CFD simulation, fabrication and experiments. The experimental results demonstrated that the working characteristics of MT-PWEH were significantly affected by position and size of the baffle. Specifically, the ratio of the maximum cut-in wind speed of 12.5 m/s to the minimum cut-in wind speed of 1.2 m/s reached 10.4. Additionally, a maximum power output of 0.78 mW was recorded at 10 m/s with an optimal load resistance of 800 kΩ and 10 LEDs were drove successfully.

A magnetic plucking frequency up-conversion piezoelectric energy harvester with nonlinear energy sink structure

In low and wide frequency vibration environments, the efficiency of vibration energy harvesters is relatively low. This paper presents a magnetic plucking frequency-up-conversion bistable Piezoelectric Energy Harvester (PEH) that features a Nonlinear Energy Sink (NES) structure for low and wide frequency vibration absorption. Based on the Euler-Bernoulli stepped beam theory, a theoretical model was derived from the Lagrange equation. The system's bandwidth and power generation capability were analyzed through frequency sweeping. This study thoroughly investigated the up-conversion working mechanism of the NES magnetically plucked PEH super-harmonic vibration. The results reveal that the system encompasses two power generation frequency bands: interwell periodic vibration and chaotic vibration. Under an excitation acceleration of 0.25 g, the interwell periodic vibration range during forward frequency sweep is from 3.30 to 4.31 Hz with an average power of 4.71 mW, and during reverse sweep, it is from 2.02 to 4.05 Hz with 2.43 mW. The coordination between NES and PEH is one of the crucial factors affecting power generation. Frequency mismatch can lead to asymmetrical displacement and alternating strong-weak voltage outputs.

Dynamics of resonant magnetoelectric effect in a magnetoactive elastomer based cantilever: Magnetic field induced orientation transition and giant frequency tuning

Magnetoelectric (ME) effects in composite heterostructures containing mechanically coupled ferromagnetic and piezoelectric layers enable the mutual transformation of magnetic and electric fields and form the basis for the development of magnetic field sensors, actuators and energy harvesters. Promising materials for such composite structures are magnetoactive elastomers (MAE), which are silicone matrices with ferromagnetic particles uniformly distributed within them. The strong dependence of MAE properties on magnetic fields and their low rigidity enable contactless control of ME effects characteristics within such structures. In this work we have experimentally investigated the dynamics of resonant ME effects in a structure consisting of a MAE layer with carbonyl iron particles and a layer of polyvinylidene fluoride piezopolymer in a cantilever geometry. For the structure magnetized in a plane along the axis, the frequency tuning of the bending oscillations reached 360 % at the fields up to 2 kOe, and the maximum ME conversion coefficient was 1.74 V/(Oe·cm). For the structure magnetized perpendicular to the plane, an orientation transition was observed, which manifested itself as a jump-like bending of the structure to the angle up to ∼850 at magnetic field above the critical value. The frequency tuning by the magnetic field reached 185 %, and the maximum ME conversion coefficient was 135 V/(Oe·cm). A model has been developed that qualitatively describes the dynamics of ME effect in composite cantilever structures with a MAE layer for different orientations of the applied magnetic field.

Resonant magnetoelectric effect in an obliquely magnetized planar ferromagnet-piezoelectric heterostructure

The characteristics of magnetoelectric (ME) effects in planar composite ferromagnet-piezoelectric heterostructures strongly depend on the direction of magnetization of the heterostructure. These dependences affect the parameters of magnetic field sensors, energy harvesters, and electronic devices based on ME effects. In this work, the frequency and field characteristics of the direct ME effect in an obliquely-magnetized heterostructure containing a piezoceramic plate of lead zirconate titanate and a nickel layer electrolytically deposited on its surface were experimentally studied. The measurements were carried out at the resonant frequency of the structure ∼85 kHz under excitation with a weak harmonic field. When the dc magnetic field deviated from the plane of the structure, the resonance frequency remained unchanged, the value of the ME coefficient gradually decreased from 5.0 V/(Oe∙cm) to a minimum, and the range of operational magnetic fields expanded towards higher fields. The transformation of the ME effect characteristics occurred due to a change of the internal field in the ferromagnetic layer caused by demagnetization. A method allowing calculating the field characteristics of the ME effect in obliquely magnetized heterostructures was proposed. The results obtained can be used to control parameters of ME devices and design vector sensors of dc magnetic fields.

Assessing mechanical and stray magnetic field energy harvesting capabilities in lead-free PVDF/BCT-BZT composites integrated with metglas

The exploration of energy harvesting encompasses a wide array of sources, with a specific focus on recovering mechanical and magnetic energy from overlooked outlets, driving current research endeavours. In this study, we developed highly flexible Magneto-Mechano-Electric (MME) harvesters by combining poly(vinylidene fluoride) (PVDF)/barium calcium zirconium titanate (BCT-BZT) composite films with metglas. The flexible piezoelectric polymer-ceramic composite films were fabricated using a solvent casting technique. The high piezoelectric BCT-BZT fillers were synthesized through a sol-gel reaction route. A thorough analysis was carried out on these composites to evaluate their structural, functional, microstructural, and dielectric properties. The composite film loaded with 20 wt% BCT-BZT filler achieved a 78 % β-phase with a significant enhancement in the dielectric properties, resulting in a high permittivity∼40 and low dielectric loss. Employing these films, we engineered nanogenerators capable of converting mechanical energy into electrical energy, yielding an output voltage of 11 V. Thereafter, to harvest mechanical and stray magnetic fields, we developed a MME generator comprising a magnetic Metglas layer and PVDF-BCT-BZT composite and achieved an output voltage of 3.3 V with a power density of 85 μW/m2 when subjected to an AC magnetic field of 5 Oe. Furthermore, the MME generator has demonstrated the ability to charge various capacitors showcasing its potential for usage in self-powered, non-contact, and implantable devices.

Harnessing the Induced Magnetostrictive Effect in Fully Flexible Fiber-Based Magnetoelectric Composites for Improved Stray Magnetic Energy Harvesting

Harnessing the Induced Magnetostrictive Effect in Fully Flexible Fiber-Based Magnetoelectric Composites for Improved Stray Magnetic Energy Harvesting

Enabling Multiple Harvesting Windows in Magnetic Energy Harvesting via Reverse Flux Desaturation

Enabling Multiple Harvesting Windows in Magnetic Energy Harvesting via Reverse Flux Desaturation

Analysis and Design of Magnetic Field Energy Harvesting for Freight Train Sensors

Analysis and Design of Magnetic Field Energy Harvesting for Freight Train Sensors

Enhanced Maximum Power Point Reaching Method for Passive Magnetic Energy Harvesters Operating Under Low Primary Currents

Enhanced Maximum Power Point Reaching Method for Passive Magnetic Energy Harvesters Operating Under Low Primary Currents

Electromagnetic vibrational energy harvester with targeted frequency-tuning capability based on magnetic levitation

Electromagnetic vibrational energy harvester with targeted frequency-tuning capability based on magnetic levitation

Improving the output performance of magnetic energy harvesters through coupling beam

We propose a novel magnetic energy harvester (MEH) with multiple resonance modes. The MEH consists of low-frequency and high-frequency piezoelectric cantilevers connected by a coupling beam. Theoretical modeling, simulation, and experiments were conducted to validate the multiple resonance phenomenon. The results from these investigations are consistent with each other. It is evident that the internal coupling (IC) effect resulting from the coupling beam facilitates significant voltage outputs from both cantilevers at their respective resonant frequencies, i.e. the low-frequency beam (LFB) resonates at the resonant frequency of the high-frequency beam (HFB), resulting in a remarkable 122% increase in the output voltage. Conversely, the HFB resonates at the resonant frequency of the LFB, leading to an astounding 1200% increase in the output voltage. As a result of the IC phenomenon, the operating frequency bandwidth for harvesting an output voltage of more than 1 V in the LFB has been extended by 35.3%, while that of the HFB for capturing an output voltage of more than 0.5 V has been extended by 62.5%. Additionally, the coupling effect significantly enhances the power output of the MEH.

An Energy Management Method for Magnetic Field Energy Harvesters Under Wide-Range Current in Railway Electrification Systems

The wide-range traction current brings great challenges to the stable operation of the magnetic field energy harvester (MFEH). Specifically, when the traction current is large, the core saturation increases, resulting in violent vibrating of the magnetic core. When the traction current is low, the energy harvested by the MFEH is insufficient to power the load. To address these vital problems, an energy management method for MFEH is proposed to track the critical saturation point, i.e., the maximum power point in the unsaturated region. In this method, by regulating the equivalent load, the core voltage is controlled at the critical saturation voltage under different current levels. Moreover, the supercapacitor is employed to store excess energy at large currents, and the stored energy is released at low currents. Furthermore, a design procedure for the core and winding is proposed in this work, which can be used to adjust the critical saturation voltage of the MFEH. A laboratory prototype is built to verify the effectiveness of the proposal. The results show that the MFEH can operate at the critical saturation point and provide stable energy for the load under different current levels. This means that saturation suppression, maximum power point tracking, and energy management can be realized by applying the proposed method.

Harnessing energy from hand-shaking vibration for electronics through a magnetic rolling pendulum bistable energy harvester

Converting the kinetic energy of human movement into electricity provides a solution for the power supply of portable electronics for communication, medical treatment, positioning, search-and-rescue, etc. Due to the characteristics of high sensitivity and snap-through, a magnetic rolling pendulum bistable energy harvester (MRP-BEH) based on magnetic-spring mechanism is proposed for scavenging energy from handshaking vibration. The harvester possessing the advantage of small damping exploits the rolling oscillation of a suspended magnet. By establishing the electromechanical model, numerical outcomes of the MRP-BEHs with different potential well depths are investigated through the response under constant and sweep frequency excitations. Particularly, the complex dynamic behaviors are characterized by basins of attraction and bifurcation diagrams. A prototype is fabricated, and experiments are undertaken under harmonic and handshaking excitations. Experimental results are consistent with numerical simulations, and excitation of 0.5 g witnesses a broadband frequency range from 5.18 Hz to 10.02 Hz for the harvester with proper system parameters. Regarding the excitation of handshaking, an instantaneous maximum power of 21.9 mW and an average power of 4.21 mW is achieved with matched load resistance. By boosting the output voltage with a transformer, the charging and discharging experiments of capacitors for powering various electronics demonstrate the broad application prospects of the harvester. This research, in a nutshell, broadens the methodology for achieving bistable oscillation and introduces a fresh perspective for designing high-efficiency energy harvesters attuned to human motion.

Study of a vortex-induced vibration piezoelectric wind energy harvester based on the synergy of multi-degree-of-freedom technology and magnetic nonlinear technology

A novel multi-degree-of-freedom and magnetic piezoelectric wind energy harvester (MNPWEH) is proposed in this work to improve the working bandwidth and output power for the wind energy harvesting based on vortex-induced vibration. In the process of studying the presented collaborative strategy utilizing multi-degree-of-freedom and nonlinear force enhancement technologies, four response states of the harvester are observed and named as inter-well state, intra-well state, pulse state, and intermittent state. The key factors determining these four response states are firstly obtained through a series of numerical simulations and pre-experiments. Then, a thorough investigation into the influence of structural parameters on these four response states and the output performance of the system has been conducted. The findings from the experimental results indicate that greater tip mass of the outer beams results in higher output voltage generated by the same state, while the excitation magnet spacing can be adjusted for meeting different requirements in power and working bandwidth. In the optimal configurations, the fabricated prototype finally can obtain a maximum average power of 1.83 mW under the condition of v = 5 m/s and s1 = 15 mm, and maintain a wide working bandwidth of 2 m/s −6 m/s with an average output power above 0.66 mW when s1 = 25 mm, respectively. The main contribution of this study has been to confirm the effectiveness of the collaborative use of the multi-degree-of-freedom technology and magnetic nonlinear technology in piezoelectric wind energy collection based on vortex-induced vibration. It also provides a deeper new insight into the performance improvement method for vortex-induced vibration piezoelectric wind energy harvester.