Finite Element Magnetic Field Research Articles

Analysis of the air gap magnetic field in cylindrical magnetic couplings based on mathematical and finite element approach

The air gap magnetic field of a magnetic coupling plays a crucial role in the examination of its static torque and eddy current losses. Precise characterization of the air gap magnetic field is essential for ensuring the accuracy of performance assessments of the magnetic coupling. This study focuses on the cylindrical magnetic coupling as the subject of investigation, employing mathematical analysis and finite element methods to evaluate and quantify the magnetic field properties. The study establishes a mathematical model of the magnetic field of a magnetic coupling based on electromagnetic field principles and the superposition theorem. An analytical formula for the magnetic flux density distribution of the air-gap magnetic field is derived. Subsequently, a three-dimensional magnetic field finite element model is created using the finite element method to numerically calculate the air gap magnetic field and validate the analytical formula. The research also explores the periodic distribution characteristics of the magnetic field in the air gap, analyzing axial differences in magnetic flux density value and direction distribution influenced by end effects.

Analysis of electrothermal shape memory alloy and disc-type magnetorheological fluid combined transmission

In this article, a disc-type magnetorheological fluid and electrothermal shape memory alloy spring-loaded slider friction combined transmission device is proposed. A heating model of the electrothermal shape memory alloy spring is used to calculate the relationship between current and spring temperature. Experiments are used to investigate the link between spring temperature and restoring force, as well as magnetorheological fluid temperature, magnetic flux density, and shear yield stress. The torque characteristics of the combined device were evaluated utilizing the coupled magnetic field and thermal field finite element method for the characteristics of the two materials. The results showed that the magnetorheological fluid showed an approximately linear decrease in shear yield stress at high temperatures, up to 37.94 %. The heating rate of the electrothermal shape memory alloy spring was influenced by the surrounding temperature, and the heating rate was too fast to easily cause the time lag of the martensite phase transformation, resulting in the spring restoring force becoming smaller, and its restoring force shows a non-linear increase when the temperature rises from 22 °C to 100 °C. By applying the two materials together, the torque of the combined transmission has been significantly increased, by 91.58 % compared to the same size magnetorheological transmission.

Enhancing a loosely coupled inductive wireless power transfer system for LED-driven slurry photocatalytic reactors

To improve the irradiation profile in a conventional photocatalytic reactor, an LED-based light emitter energized by the inductive power transmission (IPT) method has been proposed recently. However, technical challenges such as low coupling due to the asymmetrical wireless coupler, dynamic impedance due to multiple receivers and changing magnetic properties in the transmitter core, and ease in upscaling remain to be addressed. This work proposes an IPT system for an LED-based photocatalytic reactor using a toroidal transformer to match the impedance between a modified Helmholtz transmitter coil and a class-E inverter. A finite element magnetic field simulation and analytical calculation of the induced voltage are used to assess the field uniformity inside the coil. The mutual inductance at selected locations within the coil volume and the power transfer efficiency (PTE) are evaluated. The proposed system requires less than 2 W to generate a uniform magnetic field inside a 10.6 L acrylic cylinder with an induced voltage of 13.9 ± 0.95 Vrms along the cylinder’s central axis. The proposed wireless coupler achieves a coupling coefficient of 0.013–0.034 and a PTE of 23.7%, outperforming similar systems with asymmetrical coupler design while offering a versatile solution for integrating IPT technology into wastewater treatment.

Human Head Transcranial Magnetic Stimulation Using Finite Element Method

Transcranial magnetic stimulation (TMS) is a wearable neuromodulation technique. It is approved for several therapies for various neurological disorders, including major depressive disorder, traumatic brain injury, Parkinson’s disease, and post-traumatic stress disorder. This method became an alternative neuromodulation technique for such brain-related disorders. However, it has shown significant improvement in this alternative approach. Studies based on this technique have shown limited efficacy. They might be associated with current levels, poor coil locality, optimal coil size, and neuromodulator settings. It has been shown in this research that coil heating is related to higher levels of current. Thus, it is required to analyze the impact of the current levels on the induced magnetic distribution to define the optimal current range for the TMS coils. It is not feasible to investigate this research with experimental tests and analytic methods. Alternatively, using an advanced computational model of the coils and accounting for different human head anatomical layers, coil current capacity can be optimized based on finite element magnetic field distribution. This paper aims to investigate the impact of the coil current levels on the induced magnetic field distribution. The current capacity of the coils can be optimized based on the required magnetic field. In this way, the overheating may be reduced and may result in increased efficacy. As a proof-of-concept, a prototype coil and multi-layered geometrical human head models were generated using geometric shapes. The fundamental human head tissue layers were generated based on their average thickness. The model was simulated based on a finite element magnetic simulation using appropriate boundary conditions and neuromodulator settings. The various coil current levels were applied to analyze the outcome. The models were simulated, and the results were recorded based on these current levels. Results showed that there is a direct relation between applied current levels and induced magnetic flux density in the region of interest.

Numerical and experimental study on pole teeth interlaced divergent ferrofluid seals with single magnetic source

For the improvement of pressure resistance in ferrofluid seal with a small gap, a structure of divergent ferrofluid seal (FS) with alternating pole teeth (PT) was proposed in this paper. Distribution of the magnetic field in the seal gap (SG) is analyzed by using the magnetic field finite element method, and the theoretical pressure resistance (PR) is calculated by using the step ferrofluid seal PR theory. Effect of the number of pole teeth and seal gap on its sealing PR were studied experimentally. The PR of the interlaced divergent FS is compared to the experimental findings of a conventional ferrofluid seal structure. The results show that the actual pressure value of the interlaced divergent FS is consistent with its theoretical pressure value well. Compared to the common ferrofluid seal, the interlaced divergent FS has better PR.

The Efficiency Improvement of Track-Type Wireless Power Transmission Systems through Electromagnetic Finite Element Analysis

The original system, designed as a combination structure of a linear machine and a wireless power transmission transformer, was designed to overcome the limitations of the wired power supply method used for working robots and transportation equipment in existing smart factories, and improvements in magnetic coupling and power transfer efficiency are needed. In this work, we study the efficiency improvement of a system that can supply wireless power to track-type transportation equipment. For this purpose, electromagnetic properties such as magnetic equivalent resistance, inductance, magnetic coupling rate, and core loss are analyzed using the finite element method. In addition, the results of magnetic field finite element analysis are applied in electrical equivalent circuit modeling to analyze the voltage transfer ratio and input/output characteristics of a CLLC resonant converter designed for wireless power transmission. The efficiency improvements of the proposed model are verified through a comparison of experimental and simulation results after fabricating a prototype. From the results of this study, a more optimized wireless power transmission system design based on the analysis results from an electromagnetic perspective can be realized to improve the efficiency of wireless power transmission.

Optimization of structural parameters and numerical simulation of stress field of composite crucible based on the indirect coupling method

Abstract The research starts with the treatment of the multiscale transmission problem and establishes the electromagnetic solidification transmission coupling mathematical model based on the indirect coupling method. It uses the three-dimensional magnetic field finite element theory to establish a three-dimensional crucible structure continuous casting model built on the electromagnetic solidification transmission coupling mathematical model. This model is used to optimize the parameters of the composite crucible structure and to simulate electromagnetic transmission and braking phenomena. The results show that the L-shaped static magnetic field has a more potent inhibition and a guidance effect on melt circulation. The braking effect of the actual magnetic field on the downward impact is worse. Under the influence of an L-shaped magnetic field, the flow velocity of the melt is better, and the flow state distribution is more smooth and uniform. The computational efficiency test results show that the conversion calculation time of the method designed in this study is 18.03 min. The total calculation time is 680.48 min, which is superior to traditional methods. It proves that this model can accurately analyze the magnetic field coupling problem and at the same time ensure the superiority of its computing efficiency.

Conceptual Design of Scanning Magnets Using HTS Coils Wound With Spiral Copper-Plated Striated Coated-Conductor (SCSC) Cables for Carbon-ion Radiotherapy

When we reduce the size of a rotating gantry using high field superconducting bending magnets, we must also increase the magnetic field of scanning magnets. We conceptually designed scanning magnets using HTS coils wound with Spiral Copper-plated Striated Coated-conductor (SCSC) cable, which is a low-ac-loss, high current cable concept. The coils were designed to cooled at 65 K by using liquid nitrogen. We conducted the two-dimensional cross-sectional design of the HTS coils as well as warm iron yokes by finite element magnetic field analysis. AC losses in the HTS coils and iron losses in the yokes were calculated. Electrical power consumption to excite the magnets, liquid nitrogen consumption to cool the HTS coils, and the terminal voltages of the magnets were calculated to discuss the feasibility of the designed scanning magnets.

Inlet/outlet flow through various size of needle in the presence of magnetic field

Influence of Magnetohydrodynamics (MHD) on the fluid in channel flow in the presence of thin needle across the fluid movement is observed in this study. A two-dimensional computational analysis has been performed to see the effects of inlet/outlet conditions with inserted curvilinear shaped body in the channel. In this case, temperature on all boundaries is colder than that of inlet air and flat part of the inserted body. The governing equations are solved by using finite element method and magnetic field is also taken into account. With suitable dimensionless variables, PDEs are transformed into dimensionless PDEs, then raised parameter is simulated against the streamlines, isotherms and temperature distribution at mean position. Effect of Reynolds number, Richardson number, Magnetic hydrodynamic, size and state of needle is observed on local Nusselt number at the mean position. On isotherm profile, Reynolds number has a noticeable impact. With an increase in Re, heat circulation close to the needle increases, and for higher Ri, velocity on the outlet port increases. The inlet and outlet portions of the channel generate streamlines that have a significant impact on the diameter of the needle. Increased needle diameter causes heated lines to be pushed away from the centre. It is also found that the temperature gradient in the flow fields and heat transfer over the heated wall of the cavity are significant, altered by the placement of needle size during various computations.

The Study of a Magnetostrictive-Based Shading Detection Method and Device for the Photovoltaic System

When the photovoltaic (PV) system suffers shading problems caused by different degrees and areas, the shaded PV cells will consume electricity and generate heat, the corresponding bypass diode operating at a certain current will conduct, and a special magnetic field will be generated in space. In this study, a magnetostrictive-based shading detection method and device for the PV system are developed from theoretical, simulation, and physical experimental aspects. This study aims to detect the special magnetic field using magnetostrictive material with a certain response pattern under the magnetic field to detect and locate the shading problem of each module in the PV system. Theoretically, the analysis is carried out from the on–off situation of the bypass diodes of PV modules under different shading conditions and the response mechanism of magnetostrictive materials under the action of the magnetic field. During simulation, the finite element magnetic field simulations are performed for the diode and the series magnetic field coil, and the structural parameters of the magnetic field coil are designed based on the simulation results. After establishing the validation idea of the detection method in this study, the experimental platform is built and the experimental steps are designed. Finally, the feasibility of the method proposed in this study is verified, the detection range of the method is calculated, and the minimum spacing of adjacent magnetic field coils is determined by experimental validation. This study provides a novel magnetostrictive-based detection method, as well as a theoretical and experimental basis, for identifying and localizing PV system shading problems, and discusses the feasibility of shading detection at the system level.

Study on the structural design and performance of magnetorheological (MR) valve with hybrid supply magnetic source and double annular channels

Valve plays an important role in achieving precise position control for the hydraulic lift system. In order to improve the performance of hydraulic lift in precise motion, this paper proposes an MR valve with hybrid supply magnetic source and double annular channels. In addition, a structural model was established to perform pressure drop analysis. According to its working principle, it is proposed that this MR valve has two channels that work separately. There are three working modes in which the two channels work together, and the pressure drop of the MR valve can be calculated in different ways. Therefore, the MR valve with hybrid supply magnetic source and double annular channel performance test system is constructed, and the magnetic field inside the valve is simulated by performing magnetic field finite element analysis. Finally, a test bench of vehicle maintenance elevators is built to analyze whether the MR valve with hybrid supply magnetic source and double annular channels can achieve accurate control on the vehicle maintenance elevators. According to the experimental and simulation results, the pressure drop of the MR valve with hybrid supply magnetic source and double annular channels is affected by the current and channel operating mode, while the load makes little difference to the pressure drop. The worse the rising response time performance increases with increasing current, but the response time performance decreases without being affected by current. When a current greater than 1.5A is applied to the coil, the response time of the lifting platform is basically maintained at 6 s with the increase of current. The position accuracy is ±1 mm for the experimental platform of the vehicle maintenance lift table based on the MR valve with hybrid supply magnetic source and double annular channel hydraulic system.

Research on Motor Rotor Loss of High-Speed Air Compressor in the Application of Hydrogen Fuel Cell Vehicle

As an important component of hydrogen fuel cell vehicles, the air compressor with an air foil bearing rotates at tens of thousands of revolutions per minute. The heat generation concentration problem caused by the high-speed motor loss seriously affects the safe and normal operation of the motor, so it is very important to clarify the loss distribution of the high-speed motor and adopt a targeted loss reduction design for air compressor heat dissipation. In this paper, for an air compressor with a foil bearing with a rated speed of 80,000 rpm, an empirical formula and a three-dimensional transient magnetic field finite element model are used to model and calculate the air friction loss, stator core loss, winding loss and permanent magnet eddy current loss. The accuracy of the analytical calculation method is verified by torque test experiments under different revolutions, and the average simulation accuracy can reach 91.1%. Then, the distribution of the air friction loss, stator core loss, winding loss and eddy current loss of the air compressor motor at different revolutions is obtained by using this method. The results show that the proposed method can effectively calculate the motor rotor loss of a high-speed air compressor with air foil bearing. Although the motor efficiency increases with the increase in motor speed, the absolute value of loss also increases with the increase in motor speed. Stator core loss and air friction loss are the main sources of loss, accounting for 55.64% and 29% of the total motor loss, respectively. The electromagnetic loss of winding, the eddy current and other alloys account for a relatively small proportion, which is 15% in total. The conclusions obtained in this paper can effectively guide calculations of motor loss the motor heat dissipation design of a high-speed air compressor with an air foil bearing.

Numerical and experimental study of divergent magnetic fluid seals with stepped pole pieces

It is crucial that the pressure resistance of ordinary magnetic fluid seals is under small clearance conditions. Therefore, a new structure for magnetic fluid seals, i. e. a dispersion type with stepped pole pieces, is proposed in this paper to further improve the pressure resistance under such operating conditions. For the divergent magnetic fluid seal with stepped pole piece, the magnetic field distribution in the clearance can be calculated, as well as the theoretical pressure resistance of the new seal structure. In this paper, it is calculated the magnetic field distribution and theoretical pressure resistance utilizing the magnetic field finite element method based on the theory of divergent magnetic fluid seals, investigated the influence of the amount of injected magnetic fluid, the number of steps, the height of the steps and the sealing gap on the pressure resistance of the new sealing structure of stepped magnetic fluid seals, as well as compared and analyzed with that of ordinary magnetic fluid seals and normal magnetic fluid seals. The results show that the pressure resistance of the normal magnetic fluid seal is significantly worse than that suggested by the split magnetic fluid seal. The pressure resistance of the stepped magnetic fluid seal increases as the number of steps increases, while the pressure resistance of the proposed structure decreases and then increases as the height of the steps increases; and the pressure resistance of the proposed structure increases and then decreases as the radial clearance increases, while the pressure resistance of the proposed structure decreases as the axial clearance increases.

Analysis of Test Results of the Developed Synchronous Reluctance Motor for Public Transport Application

Abstract The paper describes the design and control method of the synchronous reluctance machine with improved efficiency compared to traction induction motor for electric vehicle application. Magnetic field finite element modelling is used in the design process. The paper presents load characteristics calculation method for the design process, considering the cross magnetic saturation effect. Control algorithm with constant d-axis current control method is developed in the research. The prototype of the machine is constructed and tested.

Research on the Transmission Performance of a High-Temperature Magnetorheological Fluid and Shape Memory Alloy Composite

To address the fact that the performance of magnetorheological fluid decreases with increasing temperature, a high-temperature magnetorheological fluid and shape memory alloy spring friction composite transmission method is proposed, and its transmission performance is shown to essentially maintain stability under high temperatures. We introduce a composite transmission method, performed a magnetic field finite element analysis, and present the equation of torque transmission of the composite. The results show that the amount of torque transferred by the magnetorheological fluid reached its maximum value at magnetic saturation, but decreased with increasing temperature, down to 33.41%, whereas the frictional torque generated by the shape memory alloy spring increased with increasing temperature. When the temperature reached 100 °C, the frictional torque effectively compensated for the decrease in the magnetorheological fluid’s performance.

Optimization of Three-Dimensional Magnetic Field in Vacuum Interrupter Using Particle Swarm Optimization Algorithm

Based on particle swarm optimization algorithm, a three-dimensional model of the contact system of vacuum interrupter is established. Combined with the particle swarm optimization algorithm and finite element magnetic field numerical simulation method, the contact structure parameters of a 400V/20kA vacuum interrupter is taken as the optimization variables, and the maximum magnetic field intensity at the arc root is determined as the optimization objective. The distribution of the maximum transverse magnetic field intensity at the contact gap under the optimum parameters has been illustrated and analyzed.

Preparation and regulation of AlCrNiTiSi high entropy alloy coating by a multi-arc magnetic filter cathode vacuum arc system

The high entropy alloy coatings (HECs), as a breakthrough in the field of increasingly saturated traditional material, have broad development potential, but their applications are restricted by the shortcoming of preparation technology. In this paper, based on the multi-arc magnetic filter cathode vacuum arc system, which is equipped with a 120° Y-shaped magnetic filter duct that has the reasonable match between the geometric size of magnetic filter duct and the uniformity distribution of magnetic field intensity determined by finite element analysis and magnetic field design, the transport of multiple ions is real-time regulated by the relationship among the arc source, focusing magnetic field, the magnetic field of filter duct, arc discharge and ions transmission. Under the detailed process parameters of TiAlSi target arc current of 110 A, CrNi target arc current of 90 A, magnetic field current of 2 A, and negative bias voltage of 100 V, the AlCrNiTiSi HEC is prepared by the novel multi-arc magnetic filter cathode vacuum arc technology for the first time. The AlCrNiTiSi coatings deposited by this system are uniform and dense, and the components are uniformly distributed. The AlCrNiTiSi HEC has good hardness of 13.92 GPa and excellent corrosion resistance in 5 % H2SO4 of the minimum Icorr and Ip of 3.16 × 10−6 and 1.28 × 10−5 A•cm−2.

Numerical analysis of magnetic grease seal pole teeth optimization based on pressure bearing capacity

The static magnetic field model of the magnetic grease seal was established by the nonlinear magnetic field finite element method. The influence of three typical pole teeth with different seal gaps, namely rectangular teeth, single-side trapezoid, and symmetrical teeth, on pressure bearing capacity was analyzed. The results show that the maximum pressure bearing capacity of the optimized structure is from large to small: symmetric trapezoid teeth, single-sided trapezoid teeth, rectangular teeth. The seal gap increased by 0.1 mm and pressure bearing capacity decreased by 12 %. If the teeth width was doubled, the pressure bearing capacity can be increased by 17.8%, with an optimum range of 1.8 mm to 2.2 mm. The interval length of the teeth doubled, the pressure bearing capacity increased by 30.65 %, and the optimum range for the interval length of the teeth was 1.8 mm to 2.0 mm. There was no significant correlation between teeth height and pressure bearing capacity. The study on the optimization of the teeth structure based on pressure bearing capacity could provide a reference for technical personnel to improve the efficiency and rationality of the design of the teeth for the sealing of the magnetic grease.

Numerical analysis and experimental verification of magnetic fluid sealing for air cylinder in Aerospace Engineering

In order to solve the problem of short service life (2 months) and zero leakage of air cylinder in aerospace engineering, this paper innovatively designs a magnetic fluid sealing device of air cylinder in aerospace engineering through magnetic circuit analysis and magnetic fluid sealing theory. The magnetic field finite element method is used to calculate the magnetic field distribution in the sealing gap under different key parameters such as the number of pole teeth, the height of the radial sealing gap, the thickness of the permanent magnet, the slot width, the ratio of pole piece height to shaft. And numerical analysis of the number of pole teeth, the radial sealing gap height, permanent magnet thickness, slot width, the ratio of pole piece height to shaft and other key parameters on the magnetic fluid sealing performance. Finally, the reliability of the reciprocating magnetic fluid sealing withstand voltage is verified by experimental methods. Research indicates. The pressure capabilities of magnetic fluid sealing is increasing with the increase of the number of pole teeth. The pressure capabilities of magnetic fluid sealing is decreasing with the increase of the radial sealing gap. The sealing withstand voltage increases first and then decreases with the increase of the thickness of the permanent magnet, and finally increases, and the value of the withstand voltage is the largest when the thickness of the permanent magnet is 7.8 mm. The sealing pressure capabilities increases as the slot width increases. The sealing withstand voltage increases first and then decreases as the ratio of pole piece height to shaft increases, and when the ratio of pole piece height to shaft is 0.8, the sealing withstand voltage reaches a maximum value. The pressure test finally reaches the pressure value of 6 MPa, which can meet the pressure value demand of medium pressure cylinder, indicating that the magnetic fluid sealing technology can effectively solve the leakage problem existing in the air cylinder technology of Aerospace Engineering, and improve the reliability and service life of the air cylinder.

The influence of the geometric profile of the air gap on the power and energy characteristics of an electromagnetic engine

The influence of the geometric profile of the air gap of the magnetic circuit on the power and energy characteristics of an electromagnetic engine is considered. The research is relevant because of the need to improve the methods for the optimal construction of electromagnetic engines to solve the complex problem of increasing the efficiency of vibration systems with linear displacements of executive parts. The object of research is the construction of an electromagnetic motor created on the basis of an electromagnet with a flat attracting armature. The research was performed using finite element magnetic field simulation using the program Finite Element Method Magnetics (FEMM). Options for building models are considered. The differences in the efficiency of using the compared structures of electromagnetic motors of the same size and weight from the conditions of their economy are shown. The magnitude of the electromagnetic force and mechanical work are used as evaluation criteria. The research results are interesting for specialists in the field of electromechanical engineering devices with linear displacements of executive parts.