Change Of Magnetic Flux Research Articles

Improvement of Torque Accuracy of Interior Permanent Magnet Synchronous Motor Considering Temperature Variation

Motors used as power source for electrified vehicles require secure of rotors rigidity leading by high-voltage and high-speed technology for miniaturization, large output, and high efficiency. Therefore, most of automobile manufacturers adopt Interior Permanent Magnet Synchronous Motor (IPMSM). Temperature change in Permanent Magnet Synchronous Motor leads to temperature change in permanent magnet which is inserted inside of rotor, and the change occurs into magnetic flux density change depending on the nature of material. Therefore, heat control technique and compensation for reduce power is necessary since the efficiency drop leaded by temperature change in motor of electrified vehicles directly affects power performance and mileage. This paper suggests the way to react to temperature change compensating real-time flux and torque according to motor temperature change using single Look-Up Table (LUT) which is measured at intermediate temperature. Matlab Simulink is used to verify, and Motor Dynamo is used to compare with existing method, and eventually to demonstrate feasibility.

Influence of the magnetic field on the alignment degree of the anisotropic strontium ferrites for elastomer bonded magnets

AbstractIn this work, the influence of the magnetic field on the alignment degree of the magnetic particles and on the magnetic energy flux of elastomer bonded magnets are investigated. For the investigations, a strontium ferrite filled nitrile butadiene rubber is used. The change of magnetic flux density in the injection molding tool cavity was realized by changing the current at the rectifier. The alignment degree of the magnetic particles increases with increasing magnetic field in the injection molding tool cavity. Above a certain current strength, a saturation behavior of the alignment degree of the magnetic particles and the magnetic energy flux is reached. The change of the cavity magnetic field leads to an improvement of the pole angle error up to a current of 10 A. An increase of the current above 10 A leads to hardly any improvement of the pole angle error, since a saturation in the alignment of the magnetic particles has already been reached.

Towards self-powered technique in underwater robots via a high-efficiency electromagnetic transducer with circularly abrupt magnetic flux density change

In this article, we present a high-efficiency electromagnetic transducer harvesting kinetic energy from the ocean current for self-powered technique in underwater robots to tackle the electric energy replenishment problem. A circular magnet array with alternating magnet arrangement was employed for providing a sudden change in magnetic flux density. A gear train was introduced into the compact design to greatly increase the rotation speed of the rotor. The finite element method is used to simulate and compare the magnetic flux density distributions and the induced voltages in the coil under different magnet arrays (conventional Halbach magnet array and proposed alternating one) with different magnet dimensions and numbers. The finite element method analysis shows that the alternating array displays a much larger changing magnetic flux density rate resulting in high induced electromotive forces. The experimental results based on a fabricated prototype indicate that the transducer yields maximum average output power of about 0.51 W with an energy conversion efficiency of 30.91% under the water flow speed of 0.64 m/s with a load resistance of 1 kΩ. We also investigated the capability of the transducer for self-powered applications in underwater robots. The transducer charged a 20 mF capacitor from 0 V to 29 V in 50 s. Also, the prototype charged a lithium battery embedded inside an underwater robot by 75% within 400 s. This study, with a broad application prospect, can advance the future development of self-powered underwater robotic systems.

Planar Hall sensor for quantitative measurement of pipe wall thickness reduction based on the magnetic flux density method

Quantitatively monitoring the thickness reduction of a pipe by using magnetic flux density method remains a major challenge due to the small and gradual change in magnetic flux density over a long distance along a pipe. This signal change is hindered in the background signal of a detector that has a high temperature dependence and unstable background signal. In this paper, we verify the effectiveness of magnetic flux density method in quantitatively monitoring thickness reduction through simulation and experimental verification. Experimental results show that the proportion of magnetic signal change is 1.4 mT per 10% wall loss. To support this quantitative approach, we optimise an original ultra-high-sensitivity planar Hall sensor with high thermal stability and stable background signal versus time for measurement of the magnetic field over a wide range from 0 to 50 mT. The quantitative measurements were validated on test pipes with varying thickness steps of 0.5 mm.

Eddy current separation can be used in separation of non-ferrous particles from crushed waste printed circuit boards

Waste printed circuit boards are produced greatly due to the wide application of electronic devices, in which non-ferrous metals are valuable resources. Without effective recovery processes, it can cause serious heavy metal pollution. Traditional recover technologies will cost too much energy, materials, manpower together with producing secondary ecological and environmental pollution. Eddy current separation is a green and low-cost technology to separate non-ferrous metals from others. However, it was well reported that there was a certain particle size limitation for the separated non-ferrous metals. Was it a truth or unbreakable principle for eddy current separation? In this paper, we researched the causes of the size limitation for eddy current separation. Meanwhile, the eddy current separation mechanism was detailed explained in a new comprehension related to the change of magnetic flux density, generation of eddy current force and particles’ motor behaviors. We consider that there is no size limitation for the separated non-ferrous metals in eddy current separation as long as the size of magnetic pole is enough big or small. This paper brings a new recognition about the traditional eddy current separation and will expand new application area for this environment-friendly and low-cost technology.

Light‐Controlled Room Temperature Ferromagnetism in Vanadium‐Doped Tungsten Disulfide Semiconducting Monolayers

AbstractAtomically thin transition metal dichalcogenide (TMD) semiconductors hold enormous potential for modern optoelectronic devices and quantum computing applications. By inducing long‐range ferromagnetism (FM) in these semiconductors through the introduction of small amounts of a magnetic dopant, it is possible to extend their potential in spintronics. Here, light‐mediated, room temperature (RT) FM, in V‐doped WS2 (V‐WS2) monolayers is demonstrated. The authors probe this effect using the principle of magnetic LC resonance, which employs a soft ferromagnetic Co‐based microwire coil driven near its resonance in the radio frequency regime, where it is highly sensitive to changes in magnetic flux. They use this to measure the magnetic permeability of the V‐WS2 monolayer subject to light illumination. Notably, the magnetic permeability of the monolayer is found to depend on the laser intensity, thus confirming light control of RT magnetism in this material. Guided by density functional theory calculations, they attribute this phenomenon to the presence of excess holes in the conduction and valence bands, as well as carriers trapped in the magnetic doping states, which mediates the magnetization of the V‐WS2 monolayer. These findings provide a unique route to exploit light‐controlled ferromagnetism at RT and potentially establish a new subfield named photo‐spintronics.

The device and experimental study of the monitoring of the layered soil settlement

In order to solve the problems of large measurement error, low efficiency, complex equipment operation and difficult maintenance of layered soil settlement, this paper designed a new monitoring device of layered soil settlement based on Hall effect. A number of Hall elements are arranged on the monitoring circuit board at equal spacing, and the circuit board is fixed in the aluminum tube and sealed. The aluminum tube with multiple settlement magnetic rings is drilled into the earth vertically, and the settlement magnetic rings are distributed in different soil layers. The settlement of the soft soil will move the magnetic ring, causing its position to change, which will cause the change of magnetic flux density around Hall element, and the output voltage of Hall element will also change, and then the voltage signal will be transmitted to Hall signal concentrator through RS-485 bus communication mode. The Hall signal concentrator stores the signal in FLASH and communicates with the upper computer through using the LORA wireless communication module. Through data processing and model analysis in the upper computer, the function between Hall voltage and variation of displacement of the magnetic ring is fitted. Many experimental results indicated that the error of the monitoring device of layered settlement is within 1.0567mm, and the accuracy is high. It can provide real-time monitoring to different soil layers, and the data can be exported at any time, so it has a wider application prospect.

Faraday’s Law Low-Cost Experiment Without Permanent Magnets

Electromagnetism is a complex topic for students at different educational levels. Perhaps one of the reasons for this is that students are unable to visualize the forces, fields, currents, and other electromagnetism key concepts that are related to the topic. Most teachers address this difficulty by including the use of some technological instruments such as virtual simulations, as well as hands-on experiments. This paper describes a simple experiment related to electromagnetic induction. The central principle of electromagnetic induction is Faraday’s law. Michael Faraday first stated his law in 1832 as “if a terminated wire moves so as to cut a magnetic curve, a power is called into action which tends to urge an electric current through it.” Nowadays, physicists use modern language to describe Faraday’s law of induction: “the induced emf in a closed loop equals the negative of the time rate of change of magnetic flux through the loop”; see Eq. (1):

A Study on Stator Design for Electromagnetic Noise Reduction in Washing Machine Motor

Received:11 november 2020; Accepted: 27 December 2020; Published online: 05 April 2021
 Abstract : For low cost, spoke type ferrite magnet motors with small air gap are using to washing machine. At that time, a noise problem occurs, so a design to reduce the noise is required. In the washing machine, set noise increased due to the reduction of air gap of motor at high speed spin mode. Not only the overall noise, but also the harmonics noises are greatly increased at set. As a result of set noise test and noise analysis through finite elements method, a stator tooth shoe shape in which the magnetic flux changes rapidly is cause of noise. Its shape creates many harmonics of load torque. The harmonics component of the load torque increases the overall noise of the set. The harmonics noise of the set has a large correlation with radial force component as well as the torque ripple. Especially, it is found that the harmonics noise of the set is related to harmonics component of load torque and the harmonics component of the radial force at stator tooth. The noise is reduced by applying the new design of stator tooth shoe that can minimize the change in magnetic flux through the noise cause analysis. Through this research, the harmonics noise as well as overall noise are reduced at small airgap motor. Therefore, it is possible to develop cost reduction motor for washing machine.

Investigation of wireless magnetometer in sensing magnetic field changes at different car direction and speed

The embedment of induction loop underground for traffic volume monitoring caused damaging effects to the road and reduced road surface aesthetics. A wireless magnetometer implanted underground in a small uniform area was developed to detect three-axis magnetic flux changes due to the perturbation of vehicle passing over the sensor. In this project, a wireless magnetometer sensor system operating at a radio frequency of 2.4 GHz for detecting and transmitting Z-field data has been developed to investigate the patterns of magnetic field associated with the car directions and speed. This is the first report in revealing the responses of the sensor to different car speed and sensing directions. Field tests were conducted by car passes over in a direction in-line or countering the X and Y axes of the magnetometer. The results showed that the strong magnetic field density as low as -100 to -230 μT could be generated when a car passed over the sensor in a direction countering X and Y axes. The speed detection limit of the sensor is 60 kmph. The X, Y and Z flux patterns obtained is import in designing an algorithm for accurate detection and counting of vehicles.

Study on Measurement and Alarm Device with Magnetic Fluid for Air Flow Safety

For many engineering fields, the air flow should be controlled into a safety range to ensure the production safely. A novel flow measurement device was designed for large safety range. A separable structure of the device was proposed to meet the convenience to carry. Magnet and magnetic fluid was selected as an inducting core. The characteristics of the inducting core were researched. The working principle of the measurement and alarm device for air flow safety was introduced and analyzed. The separable structure was designed to achieve two modes of the measuring and alarm device that one mode is for measuring and alarming work and the other mode is for storing and transporting conveniently. A pipe was designed for the air to pass through. Two coils were designed and chosen to be set up at two ends of the pipe to detect the changes of the internal magnetic flux and then alarm for the changes. An adjustment element was designed and set into the pipe to adjust the position of the inducting core to satisfy the requirements of the working conditions. The designed device is feasible to keep the air flow safely and to alarm when the air flow exceeds safety range.

Constituting abrupt magnetic flux density change for power density improvement in electromagnetic energy harvesting

In this paper, we originally investigate how formulation of abrupt magnetic flux density change influences the electric outputs, e.g. open-circuit voltage, power density and charging rates, of electromagnetic energy harvesters. Electromagnetic energy harvesters are comprised of one magnet array and two sets of coil arrays. In a certain volume, the dimension and number of magnets evidently determines the number of abrupt magnetic flux density change (denoted as β, β=0,1,2,3,5,7) and further the output voltage. To study how this correlation affects the performance of the harvester, a configuration is first proposed and by conducting simulation, we infer that the highest voltage is induced by the case where β=3, namely when the length, height and width of the magnet are the same. This hypothesis is further validated by three series of experimental results: the open-circuit voltage first increases, reaches its peak where β=3, and falls off sharply as β increases from 0 to 7; the cubic-magnet array configuration yields the highest power and power density, more than 20 times higher than that of the case without abrupt magnetic flux density change. The instantaneous power reaches as high as 284 mW under resonance at 1 g excitation acceleration with an overall dimension of 4.8cm × 3.9cm × 2.5cm; The charging-capacitor experimental results confirms this as the cubic magnet case yields the largest charging rate and highest saturation voltage. We mainly attribute this phenomenon to the collective relation of the flux change and magnet volume as β grows from 0 to 7. This finding reveals the best configuration of magnet arrays that leads to the most desirable performance from electromagnetic energy harvesters.

High-performance vibration power generation using polycrystalline Fe–Co-based alloy due to large inverse magnetostrictive effect

The magnetic flux density change ΔB caused by the inverse magnetostrictive effect is key for achieving high-performance vibration power generation. As the magnetization curve of the polycrystalline Fe–47.6 at. % Co–2.3 at. % V (Fe–Co–V) alloy became easier to magnetize by applying tensile stresses, the value of ΔB estimated from the magnetization curves depended significantly on magnetic fields. Hence, the vibration power generation of a U-shaped unimorph device using a polycrystalline Fe–Co–V alloy core was demonstrated under various bias magnetic fields. As a result of bias magnetic field adjustment, the open-circuit voltage induced by the vibration of the device improved to ∼7.0 V. Such superior performance is attributable to a large ΔB of 1.1 T in the Fe–Co–V alloy core. Therefore, adjustment of bias magnetic fields is essential for obtaining large ΔB in Fe–Co–V alloys, which are promising inverse magnetostrictive materials for high-performance vibration power generation.

Parametric study of an active magnetic refrigeration (AMR) system on exergy efficiency and temperature span with Gadolinium

Magnetic cooling at room temperature is one of the world’s newest technologies that can be considered as an alternative for vapor compression refrigeration systems. Magnetic cooling follows the magnetocaloric effect (MCE) phenomenon, which is justified by the change in entropy with respect to magnetic flux changes. In this research, a computational fluid dynamic (CFD) simulation of the magnetic refrigeration system is conducted in COMSOL Multiphysics 5.5 software with the geometry of sandwiched gadolinium layers and water channels. The magnetic cooling system can be analyzed in two aspects i.e. constant cooling load and zero cooling load. For this purpose, two performance indicators including the exergy efficiency and the minimum achievable temperature, can be defined for constant and zero cooling loads, respectively. Sensitivity analysis is used as a tool to understand the importance of operating parameters such as frequency, passing fluid’s velocity, cold heat exchanger temperature, magnetization, or demagnetization time. The parametric study of the zero cooling load simulation reveals that high operating frequency ( $$f = 0.5\;{\mathrm{Hz}}$$ ) besides low fluid velocity ( $$V = 0.05 \;{\mathrm{m}}\;{\mathrm{s}}^{ - 1}$$ ) results in a 51 °C temperature span. In addition, the exergy efficiency can reach the maximum value of 30 percent with respect to various velocity and frequency variables for laminated geometry.

Theoretical modeling and experimental verification of rotational variable reluctance energy harvesters

Energy harvesting has great potential for powering low-power wireless sensor nodes by converting environmental energies into the electricity. It can be widely used for real-time online industrial monitoring. Among different transducers, the variable reluctance energy harvester (VREH) has attracted much attention due to the great performance for the low-speed rotations. However, there is a lack of precise models for performance prediction. In this paper, a new modeling method for VREH is proposed to predict the output voltage. A combined Substituting Angle - Magnetic Field Division modeling method is presented to accurately model the magnetic permeance of the air–gap for the VREH. Then, the magnetic flux change in the magnetic circuit is derived to calculate the voltage response of the coil. The numerical and experimental results of voltage responses verify the effectiveness of proposed model with the maximum error of 4%. The influence of some key factors on voltage response is investigated, including the thickness of air–gap and tooth height. Moreover, power analysis demonstrates that the output power increases from 5.06 mW to 46.7 mW with the rotational speed from 100 rpm to 300 rpm.

Design of a single-phase flux radial generator with opposite poles (U-S) using permanent Neodymium magnet (NdFeB)

Nowadays, the energy crisis is one of the main problems in Indonesia. The depletion of fossil fuels is the most dominant factor. Therefore, new energy solutions are needed. Generators are an essential factor in renewable energy in generating electricity.Further research is required to create a generator that may work at low rotational speeds. Electricity supply service from year to year continues to increase in any hemisphere due to the needs of the community that separated from the demand for electrical energy, especially in Indonesia. There are still many regions of Indonesia that have not to be electrified, especially remote areas, borders, and outer islands. Thus, alternative energy sources are needed, such as new and renewable energy, as electricity producers. One effort to overcome the scarcity of electrical power is the use of water and wind energy in electricity generation both on a large scale and on a small scale. Indonesia has considerable wind potential related to the energy sector, but this system also requires batteries or energy storage media. Innovations on energy conversion technology, especially in permanent magnet NdFeB permanent radial and axial flux generators have been developed. An electric generator is a device that can convert mechanical energy (motion) into electrical energy. In designing radial flux generators with opposite poles, they have 24 coils on the stator and 12 magnets on each rotor, where each coil has 450 windings connected in series with 24 Neodymium Iron Boron (NdFeB) magnets on the rotor. The diameter of the email wire used in this generator is 0.3 mm. Tests carried out using a resistive load of 3000 Ω, which is paralleled as much as 1, 2, and 3 as a load. Tests carried out on the voltage, current, and rotational speed of the rotor to determine the power and efficiency of the generator. The test results show that this magnetic flux change produces a voltage of 101 volts without load.

Design/exploration and verification of an electromagnetic probe for assessing dental implant osseointegration

Osseointegration is the key to the success of surgery of dental implantation. In this study, we proposed, implemented and explored a handheld and noncontact electromagnetic-type stability assessment device for the use after surgery. The device with two pairs of dual inductors incorporating with a driving signal of swept wavelets was first proposed. This detection device feeds 200–10 kHz of alternating current into an inductor to produce swept broadband magnetic flux and excite the implant structure with a magnetic pole. The implant vibration causes magnetic-flux changes and generates an induced electromotive force. The implant structure resonance frequency (RF) can be characterized to exhibit osseointegration status by evaluating the frequency response function. In vitro bone block experiment and in vivo animal testing were performed to validate the developed device. For bone block experiment on fourteen designs, besides two cancellous bones and two cortical-shell thicknesses, four interface tissues produced using varied mixing ratios of epoxy adhesive were to imitate osseointegration progress. Further, a pilot animal test was conducted on five female New Zealand rabbits to assess implant osseointegration in live bodies. Statistical analyses for varied bone models on measured RF, and the regression analysis between the measured RF and OsstellTM ISQ for in vivo testing were performed. The correlation analysis on the built regression models shows a close relationship between the measured RFs and ISQ quotients with the determination coefficients up to over 0.9.

Fast Quantitative Method to Detect the Cross-Sectional Loss of Wire Rope Defects

The loss of metallic area is the most important factor affecting the quality of wire ropes. Therefore, it is very important to detect the loss of metallic area values of wire rope defects quickly and accurately. At present, the main flux detection approach is one of the most effective methods, and the detection signal is related directly to the metal cross-sectional area of the wire rope. However, when the defect width is less than a specific value, the existence of the leakage magnetic field means that the amount of the magnetic flux change is not only related to the loss of metallic area of the defect but also has a complex nonlinear relationship with the defect width. The resulting calculation is highly complex and means that the loss of metallic area cannot be determined quickly and quantitatively. This article presents an in-depth study of the theoretical basis of magnetic flux detection, analyzes the problems of the main magnetic flux detection method and their causes, and proposes a method to improve main magnetic flux detection using the axial magnetic flux density. Simulation analysis and experimental results show that the method presented in this article can be used to calculate the loss of metallic area values of defects quickly and accurately without the need for complex calculation processes.

Improved sensitivity and bandwidth of hybrid magnetic sensor based on electrically modulated amorphous magnetic alloy/piezoelectric composite

This study reports an electrically modulated dc and low frequency magnetic sensor with high sensitivity and wide bandwidth. It is based on multiferroic composites consisting of amorphous magnetic alloy Metglas/piezoelectric transformer (i.e., Pb(Zr,Ti)O3/Pb(Zr,Ti)O3)/Metglas layers winded with capacitor connected excitation coils and pickup coils. By electrically exciting the piezoelectric transformer winded with coils, the periodically induced stress and magnetic field modulate the magnetization of Metglas simultaneously and cause the change of magnetic flux within the pickup coils. The output voltage is further enhanced with the resonant converse magnetoelectric (CME) and mutual inductance effects at the mechanical and LC resonance frequency, respectively. Furthermore, the asymmetric wide bandwidth property of hybrid magnetic sensor provides the enhanced low frequency magnetic field sensitivity with negligible extra power consumption compared to the CME effect. When the magnetic sensors are excited with 5 V voltage at the resonance frequency and applied with 10 Hz magnetic field, the hybrid magnetic sensor achieves the maximum magnetic field sensitivity of 2.20 V/Oe and this is about 4.89 times as high as that of CME effect (0.45 V/Oe). The limit of detection for 10 Hz magnetic field is also noticeably improved from 2.97 nT for CME effect to 590pT for the hybrid magnetic sensor.

Molecular beam magnetic resonance coupled with a cryogenically cooled, pulsed laser vaporization source and time-of-flight mass spectrometry

A molecular beam magnetic resonance apparatus designed for the study of polyatomic molecules and small metal clusters is described. In contrast to atoms, vibrational and rotational excitation in clusters and molecules invoke spin relaxation upon a change of magnetic flux density. To prevent this, a pulsed laser vaporization source with a cryogenically cooled nozzle is utilized to minimize thermal excitation and a magnet setup has been designed to diminish magnetic field fluctuations. The apparatus is evaluated by Stern–Gerlach and resonance experiments on an atomic europium beam with the identical pulsed laser vaporization source.