Electromagnetic Finite Element Research Articles

Research on the Influence of Projectile Width on the Efficiency of Reconnection Electromagnetic Launchers

Reconnection electromagnetic launcher is a kind of electromagnetic launcher, which has excellent performance of launching. The change of projectile width has a great influence on the launching efficiency of reconnection electromagnetic launcher. The influence of the reverse vortex generated on both sides of the projectile on the launch efficiency when the projectile width increases is studied in this article. First, the model and basic principles of the reconnection electromagnetic launcher are introduced, and then the electromagnetic finite-element software is used to carry out a large number of simulations to study the launch model. The results show that when the projectile weight is kept constant by digging out a part of the projectile, and the projectile width increases within a certain range, the launch efficiency will increase as the width of the projectile increases, the increasing trend is smaller and smaller, and finally it will gradually decrease. When the mass of the projectile is determined, there is an optimal width. Finally, the eddy current distribution in the projectile is analyzed, and it is found that when the projectile has a wide width, the eddy current opposite to the eddy current in the middle of the projectile will appear on both sides of the projectile. Through the analysis of electromagnetic force, it can be concluded that the reverse eddy current is beneficial to the launch. Therefore, when keeping the weight of the projectile constant and only increasing the width, the efficiency will gradually increase. When the width of the projectile is highly wide, the excavated part of the projectile is very large, which starts to affect the vortex distribution and reduce the efficiency. This research provides a reference for the design of the projectile of the reconnection electromagnetic launcher.

Equivalent Circuit Modeling and Experimental Analysis of Low Frequency Metamaterial for Efficient Wireless Power Transfer

This study proposes a low-frequency metamaterial(MM) coupled with an equivalent circuit model to emulate the behavior of an MM-based Wireless Power Transfer (WPT) system. For this purpose, the electromagnetic simulation and Finite Element Analysis (FEA) of the proposed MM-based WPT system are performed in ANSYS three-dimensional (3D) High-Frequency Structured Simulator (HFSS). In addition, numerical analysis of the circuit design of the proposed structure is performed in a MATLAB simulation environment to evaluate its transfer characteristics. While some methods, including effective medium theory and transmission line circuit model, have been exploited to explain the physical mechanism of MM-based WPT systems, some of the reactive parameters and the fundamental physical interpretation have not been clearly expounded. In contrast to existing theoretical models, the proposed approach focuses on the effect of system parameters of the MM and transfer coils on transfer characteristics, coupled with its effectiveness in analyzing complex circuits. A design prototype is fabricated for experimental measurement of power transfer efficiency and medium parameters using the KeySight ENA 5061 vector network analyzer (VNA), confirming the validity of the proposed design. The excellent efficiency enhancement and mutual coupling make the design an attractive solution for WPT applications. A close agreement of the experimental results and numerical simulation validates the accuracy of the analytical model.

Research on Losses and Heat Dissipation of Saturable Reactor Used in Converter Valve

Based on the analysis of the principle and structure of a saturable reactor used in a converter valve of HVDC transmission, this paper analyzes its power loss composition and summarizes and derives the power loss equations. According to finite element analysis, the saturable reactor is modeled, its transient electromagnetic characteristics are simulated, and the core loss density distribution is studied. The influence of the cooling circuit and air on the heat dissipation of the saturable reactor is studied. The power loss density obtained by the electromagnetic field finite element analysis is mapped as the heat source to the finite fluid element for thermal simulation in order to obtain the spatial temperature distribution of the saturable reactor. The maximum temperature of the case is about 68.5°C, while the maximum temperature of the iron core is about 87.9°C. The converter valve operation test validates the accuracy of the heat dissipation analysis and temperature field simulation. The research results can serve as a reference for the design of saturable reactors used in converter valves.

Artificial Monitoring of Eccentric Synchronous Reluctance Motors Using Neural Networks

This paper proposes an artificial neural network for monitoring and detecting the eccentric error of synchronous reluctance motors. Firstly, a 15 kW synchronous reluctance motor is introduced and took as a case study to investigate the effects of eccentric rotor. Then, the equivalent magnetic circuits of the studied motor are analyzed and developed, in cases of dynamic eccentric rotor and static eccentric rotor condition, respectively. After that, the analytical equations of the studied motor are derived, in terms of its air-gap flux density, electromagnetic torque, and electromagnetic force, followed by the electromagnetic finite element analyses. Then, the modal analyses of the stator and the whole motor are performed, respectively, to explore the natural frequency and the modal shape of the motor, by which the further vibrational analysis is possible to be conducted. The vibration level of the housing is furtherly studied to investigate its relationship with the rotor eccentricity, which is validated by the prototype test. Furthermore, an artificial neural network, which has 3 layers, is proposed. By taking the air-gap flux density, the electromagnetic force, and the vibrational level as inputs, and taking the eccentric distance as output, the proposed neural network is trained till the error smaller than 5%. Therefore, this neural network is obtaining the input parameters of the tested motor, based on which it is automatically monitoring and reporting the eccentric error to the upper-level control center.

Coupled Magnetic Field and Thermal Analysis Model for an IPMSM With Modular Three-Phase Winding Topologies for Fault-Tolerant Applications

Multi three-phase machines are frequently recommended for high current and high power applications due to their ability to minimize phase current while maintaining rated power and phase voltage. Furthermore, multi three-phase machines are also proposed because of their fault-tolerant capability to operate in partial working conditions due to their redundant structure. A partial working condition may occur when one or more three-phase winding sets go into faulty condition. This article focuses on evaluating the thermal behavior and efficiency of a multi three-phase machine comprising different modular winding topologies to investigate its normal, partial, and partially overloaded operation. The machine prototype used in the analysis is an interior permanent magnet synchronous machine (IPMSM) having six three-phase winding sets configured in modular three-phase winding arrangements. Firstly, the prototype machine’s losses, efficiency, and output torque performances are evaluated through electromagnetic finite element analysis (FEA) for the different modular three-phase winding topologies applying similar operating conditions. Then the machine’s thermal behavior is evaluated for the modular (concentrated, distributed, and combined concentrated and distributed) three-phase winding topologies through a coupled magnetic field and thermal analyses under the machine’s healthy, partial, and partially overload operations. Finally, a comparative thermal analysis is presented for the machine prototype along with experimental validations for the analyzed modular three-phase windings topologies. This research study suggests the best modular three-phase winding topology for a multi three-phase machine considering efficiency performance and mutual heat exchange phenomenon between different three-phase independent winding sets, particularly for the machine’s partial and partially over-load working conditions.

Research on dynamic characteristics of three-shafts ring-plate magnet gear

Dynamic characteristic analysis is the key step to improve the transmission performance of eccentric permanent magnet gear. The study of this step can not only analyze the dynamic force process of each transmission part, but also improve the operation stability and bearing capacity of eccentric permanent magnet gear. Taking three-shaft ring-plate magnet gear (TRMG) as the research object, based on its operation mechanism and dynamic model, this paper establishes the balance equation of force and torque of each part of TRMG. Through the combination of electromagnetic finite element simulation and mathematical analysis method, the force of the input shaft and the supporting shaft in the TRMG motion process is solved. By improving the TRMG power input mode, the dynamic performance of TRMG is optimized, and the stability of transmission structure is improved. The feasibility of this new transmission mode is verified by multi-body dynamics analysis.

Research on Dynamic Control Method of Loom Spindle Braking System Based on Fuzzy Neural Network

Aiming at the problems of slow response speed of loom electromagnetic braking system and low accuracy of parking angle after braking, resulting in driving marks and thin and dense roads of fabrics, a braking control system based on fuzzy theory and BP neural network is proposed to improve the response speed and control accuracy of the braking system. Firstly, the transmission torque in the braking process of the loom is dynamically analyzed by establishing the mathematical model of electromagnetic braking and the Ansoft electromagnetic finite element model. The causes of braking angle slip are explored, and the driving mechanism of the electromagnetic clutch control circuit based on PWM pulse is analyzed. Based on the control strategy of excitation current, by introducing the fuzzy theory and BP neural network, a fuzzy electromagnetic braking control system based on a neural network is proposed to improve the adaptive ability of the system. At the same time, the IBA-BP algorithm is used to train the neural network to avoid the generation of local optimization and improve the control accuracy of the system. The simulation and experimental results show that compared with PID control and fuzzy PID control, the neural network method based on fuzzy theory has a smaller braking slip angle, and the accuracy of parking angle after braking action is less than 10 °, which improves the control accuracy of loom electromagnetic braking system and weaving quality.

Electromagnetic Finite-Element Modeling of Induction Effects for Buried Objects in Magnetic Soils

A frequency-based finite element (FE) framework has been developed to predict and understand the response of an electromagnetic induction (EMI) sensor due to buried targets. The EMI sensor is used to detect buried targets in magnetic nonconducting soils. The framework was verified with an analytical model that utilizes dipole approximations. The framework was then used to predict the electromagnetic (EM) response due to interrelated stimuli and properties. The results indicate that the sensor was not sensitive to small variations (0–200 mm) in the standoff height and lateral positions, and only showed a significant change in the response due to stand-off variations that were greater than 200 mm. This low sensitivity to minor variations in standoff height and lateral position signify that there are critical distances related to the EM response of buried objects. The response to different target conductivities and permeabilities was also investigated for steel and aluminum targets. The lower conductivity steel targets had EM responses, where the inductive limit was reached at higher frequencies than the higher conductivity aluminum targets. Variations in target permeabilities for steel showed that as permeabilities increased, the frequencies at which the inductive limit was reached also increased. This verified predictive approach can provide a methodology to characterize the EM response of buried objects for a broad class of buried object EM properties, geometries, and input stimuli.

A comparative study on the performance of SSDR coreless AFPM generators with conventional and Halbach magnet arrays

An axial flux permanent magnet (AFPM) generator is known to be a good candidate for both low- and high-speed applications. In this paper, a comprehensive comparison of four coreless AFPM generators is presented with conventional and Halbach magnet arrangement combined with iron and ironless rotor (epoxy). With the same coreless stator structure, four different AFPM generators with different rotor magnet arrangement and materials are compared in terms of voltage, current, power, machine weight, and power density. The analytical design approach is first presented and is subsequently validated using ANSYS Maxwell electromagnetic finite element analysis (FEA) software. Results show that AFPM machine with fully coreless topology using Halbach array with epoxy rotor can deliver similar power density but has a lower cost compared to conventional magnet array with iron rotor. Hence, this topology is favorable for low power low cost applications.

Multiobjective and Multiphysics Design Optimization of a Switched Reluctance Motor for Electric Vehicle Applications

Switched reluctance motors (SRMs) have attracted much attention in industry due to the advantages of low cost, robust structure, high fault tolerance and high torque density. However, several disadvantages like high torque ripples and coil temperatures hinder their industrialization for some applications requiring high dynamic performance, like electric vehicles (EVs). In this paper, a multiobjective and multiphysics design optimization method considering both thermal and electromagnetic performance is presented for a 12/10 SRM. First, the topology of the SRM is introduced and the optimal parameters are defined. Then, the electromagnetic finite element model (FEM) is introduced and the 3D transient lumped-parameter thermal model (TLPTM), considering both axial and radial heat transfer for the SRM, is proposed. Second, the objectives and constraints of the optimization are determined. To improve the optimization efficiency, the sequential subspace optimization strategy is employed to find the optimal solution of this high-dimensional design optimization problem. Finally, to validate the effectiveness of the proposed method, both simulation and experimental results are given and discussed. Compared with the initial design, the optimal solution exhibits lower temperature, higher torque, lower torque ripple and less loss.

Temperature field characterization and optimization of temperature field distribution in pipe lining process based on electromagnetic induction heating system

It is a promising treatment strategy to use an induction heating system for pipe lining, which can void the low efficiency and difficult temperature control of the traditional flame and hot air heating. In this study, a novel finite element model of pipe scanning induction heating was established, and the reliability of the model was verified through experiments. In addition, through the Plackett-Burman design, the main factors affecting the temperature fluctuation at 5 mm of the lining layer are analyzed. Finally, based on the analysis results, the system parameters were optimized by response surface method and the parameter configuration of the induction heating system with the minimum temperature fluctuation of 5 mm lining layer was obtained. The model established in this paper greatly reduces the calculation time of the electromagnetic induction heating finite element model of the moving magnetic field. It can be applied to the temperature information prediction of the lining induction heating where high-temperature accuracy is required and provides a reference for the characterization of the lining induction heating system and its application in low-temperature heat treatment, and the modeling strategy can be extended to the characterization of the temperature field evolution of any mobile heat source.

Development of a novel magnetorheological brake with zigzag magnetic flux path

In this research work, a novel disc-type configuration of magneto-rheological brake (MRB) with zigzag magnetic flux path is proposed. In this design, a rotor component consisting of several magnetic plates integrated in a disc made of non-magnetic material is implemented. A magnetic plate is separated with the others by nonmagnetic separators of the disc. Corresponding magnetic plates and separators are also implemented on the housing of the MRB. With this configuration, the magnetic flux line is forced to cross the MR fluid (MRF) duct from the disc to the housing at this separator and then from the housing to the disc at the next separator. This results in a zigzag magnetic flux path between the disc and the housing. The separators on each side of the housing are integrated on a bobbin, on which the magnetic coil is installed. When counter currents are applied to the coils on each side of the housing, a mutual magnetic field with zigzag flux lines across the MRF duct is generated. Based on the electromagnetic finite element and torque analysis, optimization problem considering the maximum achievable braking torque and the minimum mass of the MRB is performed. After that, optimal results of the MRB are obtained and compared with those of MRBs in previous works. Based on optimal results of the MRB with a maximum achievable braking torque of 20 Nm, an MRB prototype is fabricated and experimentally investigated to validate the simulation results.

Analysis and Experimental Comparison of Acoustic Noise of Three Switched Reluctance Motors Made of Conventional Steel, High Silicon Steel, and Amorphous Iron

In this article, three test motors are fabricated with different iron materials, conventional steel, high silicon steel, and amorphous iron. Among the three materials, the high silicon steel has the lowest magnetostriction and the amorphous iron has the highest magnetostriction and the lowest saturated flux density. Hammer test is carried out to identify the respective resonant frequency and the optimum Young's modulus and Poisson ratio are identified from the measured resonant frequency for each core. Furthermore, the acoustic noise is measured in load test and it is found that the high silicon steel has the lowest acoustic noise. Then, the electromagnetic finite element analysis (FEA) and acoustic noise analysis are carried out. According to the FEA results, the acoustic noise of the amorphous iron motor is the lowest, while it is the highest in an experiment. This discrepancy is considered to be resulted from the magnetostriction property of the magnetic materials that are ignored in FEA so far. Therefore, the magnetostriction of three iron sheets is measured and the FEAs that take magnetostriction into consideration are carried out. From the results of the improved FEAs, it is found that the magnetostriction plays an important role in acoustic noise analysis.

선박용 전자 유량계의 측정 정확도 향상을 위한 여자 코일 시스템의 영향에 관한 연구

An electromagnetic flowmeter calculates the velocity of the fluid and volumetric flow rate by measuring the induced voltage generated by the internal magnetic field. However, because the velocity of the fluid changes according to various external conditions, the uniformity of the magnetic flux density in the measurement section is critical for the accurate measurement of the flow rate. In this study, an improved coil system was proposed to analyze the influence of the internal structure of the electromagnetic flowmeter and to increase the measurement accuracy. The proposed design was verified by analyzing the magnetic flux density distribution via 3D electromagnetic finite element analysis and via experiments using a manufactured prototype.

Fabrication, simulation, and characterization of planar inductors

A planar inductor with excellent magnetic characteristics was successfully prepared by screen printing high solid content iron-based alloy magnetic pastes onto copper-clad laminates (CCL). The sample was then cold-isostatic pressed (CIP) to increase the packing density. To solve the problems of low electrical resistivity and low power handling capability of alloy powders for power inductor applications, an epoxy resin vehicle was added to form an insulating layer on top of the iron-based alloy powder surfaces and distribution gaps between the alloy powders. A central column was formed by punching in the center of the planar inductor and filled with magnetic paste to increase the inductance, magnetic flux channeling, and storage energy. A planar inductor 8.5 mm × 7.0 mm× 0.4 mm in size with an inductance value of about 2.7 μH at 1 MHz, a quality factor of 10–13, and inductance decline rate of about 5% at a DC bias of 2.5 A can be successfully prepared using the proposed method. A 3D electromagnetic field finite element analysis tool (ANSYS Maxwell R19.3) was used to simulate the coil geometry and magnetic paste formulation effects on the magnetic flux density distribution, and the planar inductor electromagnetic properties to identify the optimal parameters. The differences between the simulation and the experimental planar inductor DC-bias superposition characteristics were compared. The deviations between the measured and simulated results are only within 6%, suggesting that the simulation has very high accuracy and reliability.

Sensing delamination in composites reinforced by ferromagnetic Z-pins via electromagnetic induction

This paper investigates a novel technique for sensing delamination in through-thickness reinforced composites based on electromagnetic induction. This sensing technique features ferromagnetic Z-pins and a pair of coils attached to a laminate; the first coil creates a magnetic field that is intensified by the ferromagnetic pins, whilst the second coil detects the magnetic flux change that is caused by the pin motion relative to the coil pair when delamination happens. This approach avoids potential interferences due to contact electrical resistances that exist in electrical-based sensing approaches. The viability of this sensing technique is demonstrated by monotonic and cyclic bridging tests, involving Nickel/Iron alloy Z-pins embedded in E-glass/913 laminates under controlled delamination. A simplified electromagnetic finite element analysis is presented to help interpret the experimental results. The sensitivity of the magnetic-based sensing technique increases with loading rate. Both mode I and mode II delamination events can be detected by a voltage signal from the sensing coil, albeit there exists an initial “blind spot” at low loading rates. This sensing technique also allows monitoring the pin bridging status, e.g. the switch of pin pull-out side, without modifications to the architecture of a Z-pinned composite regarding expected mechanical response.

Analysis of the Influence of the Number of Coil Pairs Per Wing on Multiwing Reconnection Electromagnetic Launcher

The multiwing reconnection electromagnetic launcher is a variant of the plate reconnection device, and its working principle is the same as the reconnection device. The multiwing reconnection electromagnetic launcher is a geometrically complementary symmetrical mechanism, which can effectively improve the stability of the projectile. First, this article introduces the basic principle of one-stage plate reconnection electromagnetic launcher, and then focuses on the influence of the number of drive coil pairs per wing of the four-wing reconnection electromagnetic launcher on the launch performance. A four-wing reconnection electromagnetic launch model was established, the driving coil pairs of each wing are 1, 2, and 3, respectively, and the overall inductance of the coils of each wing consistent in three cases is ensured through the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> oscillation simulation. From the results of electromagnetic finite element method simulation, it is indicated that when the number of coil pairs per wing is 1, the projectile’s exit velocity is 474 m/s and the efficiency is 15.10%. This article shows that the most efficient acceleration of the projectile uses one driving coil pair per wing. More coil pairs per wing result in lower exit velocities and efficiencies. Finally, the phenomenon is explained from the perspective of the interaction between the magnetic field and the eddy current.

Evaluation of waste heat recovery of electrical powertrain with electro-thermally coupled models for electric vehicle applications

The mile range of an electric vehicle (EV) may be reduced significantly in cold weather owing to the energy demand for meeting thermal comfort in the vehicle cabin, as waste heat from a combustion engine is not available for this purpose. Various heat pump-based heating, ventilation, and air conditioning (HVAC) systems can be employed to absorb the heat energy from the surroundings and/or the waste heat from the electrical powertrain to facilitate cabin thermal comfort, thereby extending the EV mile range. However, there is a lack of research on the electro-thermally coupled modelling and evaluation of the thermal performance of HVAC systems. This paper proposes electro-thermally coupled models for the electrical machine and inverter by modelling the key electromagnetic quantities as functions of the torque and speed based on offline parameter extraction from two-dimensional electromagnetic finite element analysis. The proposed electro-thermally coupled models, which are computationally efficient, are integrated into HVAC thermofluid simulation. Comparative studies of three heat pump-based HVAC architectures (conventional ambient heat only, waste heat only, and dual heat source) are performed using the proposed electro-thermally coupled models. The dual heat source HVAC architecture exhibits superior thermal performance over its counterparts in cold weather conditions.

Modeling of Bearing Voltage in Electric Machines Based on Electromagnetic FEA and Measured Bearing Capacitance

Bearing voltages and associated bearing currents in electric machines driven by pulsewidth modulation converters with high switching frequencies and high dv/dt can cause premature bearing failures. This article proposes a new modeling approach for the prediction of steady-state and transient bearing voltages based on two-dimensional (2-D) electromagnetic finite element analysis with coupled external circuits using measured bearing capacitance values. The distributed-element external circuit was employed mainly to take into account the influence of wire distribution and frequency dependency, which are typically neglected by traditional equivalent circuits. The developed model was then used to simulate bearing voltages for various scenarios and evaluate the effectiveness of several easy-to-implement bearing voltage reduction methods from the perspective of machine design and manufacturing, such as using the insulated shaft and/or bearings, introducing additional insulation in the rotor, and changing the material of machine components. Experimental measurements are also provided to facilitate the analysis and validate the proposed approach.

Modeling and validation of stray-field loss inside magnetic and non-magnetic components under harmonics-DC hybrid excitations based on updated TEAM Problem 21

Purpose This paper aims to propose and establish a set of new benchmark models to investigate and confidently validate the modeling and prediction of total stray-field loss inside magnetic and non-magnetic components under harmonics-direct current (HDC) hybrid excitations. As a new member-set (P21e) of the testing electromagnetic analysis methods Problem 21 Family, the focus is on efficient analysis methods and accurate material property modeling under complex excitations. Design/methodology/approach This P21e-based benchmarking covers the design of new benchmark models with magnetic flux compensation, the establishment of a new benchmark measurement system with HDC hybrid excitation, the formulation of the testing program (such as defined Cases I–V) and the measurement and prediction of material properties under HDC hybrid excitations, to test electromagnetic analysis methods and finite element (FE) computation models and investigate the electromagnetic behavior of typical magnetic and electromagnetic shields in electrical equipment. Findings The updated Problem 21 Family (V.2021) can now be used to investigate and validate the total power loss and the different shielding performance of magnetic and electromagnetic shields under various HDC hybrid excitations, including the different spatial distributions of the same excitation parameters. The new member-set (P21e) with magnetic flux compensation can experimentally determine the total power loss inside the load-component, which helps to validate the numerical modeling and simulation with confidence. The additional iron loss inside the laminated sheets caused by the magnetic flux normal to the laminations must be correctly modeled and predicted during the design and analysis. It is also observed that the magnetic properties (B27R090) measured in the rolling and transverse directions with different direct current (DC) biasing magnetic field are quite different from each other. Research limitations/implications The future benchmarking target is to study the effects of stronger HDC hybrid excitations on the internal loss behavior and the microstructure of magnetic load components. Originality/value This paper proposes a new extension of Problem 21 Family (1993–2021) with the upgraded excitation, involving multi-harmonics and DC bias. The alternating current (AC) and DC excitation can be applied at the two sides of the model’s load-component to avoid the adverse impact on the AC and DC power supply and investigate the effect of different AC and DC hybrid patterns on the total loss inside the load-component. The overall effectiveness of numerical modeling and simulation is highlighted and achieved via combining the efficient electromagnetic analysis methods and solvers, the reliable material property modeling and prediction under complex excitations and the precise FE computation model using partition processing. The outcome of this project will be beneficial to large-scale and high-performance numerical modeling.