Electromagnetic Force Analysis Research Articles

Characteristic Analysis of Electromagnetic Force in an HTS Field Coil Using a Performance Evaluation System

A performance evaluation system (PES) can experimentally test the structural stability and magnetic field effects of HTS coils against high magnetic fields and electromagnetic forces before mounting the HTS coils on a large-capacity rotating machine. This paper deals with the characteristic analysis of electromagnetic force in an HTS field coil for a 10 MW Class HTS Wind Power Generator using PES. Based on the designed 10 MW class HTS wind power generator, the HTS coils are manufactured and installed in the PES by a support structure, which is designed considering the electromagnetic force (torque) and heat loads in the HTS coil. To check the stress and deformation in the support structure caused by the electromagnetic force generated from the coil, strain gauge sensors were attached to the support structure and measured under full-load conditions. As a result, the maximum magnetic field and electromagnetic force are 2.8 T and 71 kN, respectively. Compared to the analysis results, the magnetic field and generated electromagnetic force in the HTS coil were the same under no-load and full-load conditions. These results will be effectively used to study and fabricate high magnetic field coils for HTS applications, as well as the PES being fabricated.

Design and harmonic analysis of single winding bearingless PM synchronous motor with high winding coefficient

Compared with double-winding bearingless permanent magnet synchronous motor, single-winding bearingless permanent magnet synchronous motor (SBPMSM) has the advantages of low copper loss and low failure rate. However, if the slot-pole combination of SBPMSM is not reasonably selected, the winding coefficient will be reduced, and even many advantages of the single-winding structure will be offset. In this paper, a single-winding design method based on magnetomotive force (MMF) star diagram is proposed, which can ensure high winding coefficient. The design process of the proposed single winding structure is introduced. This method can match the appropriate number of stator slots according to the number of rotor poles, and the winding phase separation design can be realized by reversing the slot number transposition. The mathematical models of the suspension force and torque of the bearingless permanent magnet synchronous motor are derived considering the magnetic field harmonics, and the 6-slot/2-pole SBPMSM and 18-slot/8-pole SBPMSM are taken as examples to analyze the magnetic field. The finite element simulation models of 6-slot/2-pole SBPMSM and 18-slot/8-pole SBPMSM are built and analyzed. Through the analysis of electromagnetic torque, suspension force and air-gap magnetic field under different magnetic fields, the general rules of main torque fluctuation and suspension force fluctuation are summarized.

Steady State Electromagnetic Force Analysis of Hyperloop Tube Considering Nonlinear Material Properties by FEM

Steady State Electromagnetic Force Analysis of Hyperloop Tube Considering Nonlinear Material Properties by FEM

Comparative the effect of distribution transformer coil shape on electromagnetic forces and their distribution using the FEM

Abstract During the normal life of the transformers, they are subjected to different electromagnetic stresses. One of these stresses is the electromagnetic forces resulting from the passage of short-circuit current in the transformer coils due to internal or external faults and may lead to the failure of the transformer when this electromagnetic force exceeds the threshold level. This work deals with the computation and analysis of leakage magnetic flux and electromagnetic forces when the worst-case fault (symmetrical short-circuit current) occurs in distribution transformer (DT) coils using the finite element method (FEM). The three types of DTs that were adopted in this work are similar in capacity and voltage transformation ratio (250 kVA and 11,000/416 V), but they are different in the shape of coils (oval, cylindrical, and rectangular coils). ANSYS software was used to build two-dimensional models of the three transformers, which were different in coil shapes and in the type of iron core. The objective of this work is to compare the effect of coil shape on the distribution of electromagnetic forces and their value, in order to find out which coil shape is the best to withstand electromagnetic forces when short-circuit current is passed in the coils. The results of the simulation of the finite element models were approximately equivalent to the results of the design calculations that depend on the classical method (the analytical method), but the FEM is more accurate, due to the accuracy of calculating the magnetic flux and its distribution, which cannot be calculated using the classical method. One of the most important contributions of this research is the analysis and calculation of electromagnetic forces for three types of DTs with different coils by applying the same design parameters to all the transformers. The research also contributed to determining the best coil shape by comparing simulation results, and it was found that transformers with cylindrical coils are the best to withstand electromagnetic forces due to the homogeneity of the cylindrical coil structure from all sides.

Comparative numerical analysis of electromagnetic forces in DC and HFPC TIG welding

The paper presents a detailed theoretical analysis of the electromagnetic forces in the arc plasma and the weld pool metal in Tungsten Inert Gas (TIG) welding at direct current (DC) and high-frequency pulse current (HFPC) modulation with a frequency of 10 kHz. The electromagnetic (Lorentz) force, acting on arc plasma and metal is presented via potential (magnetic pressure) and rotational (equivalent electromagnetic force) force components. This approach allows us to substantially simplify the analysis of the Lorentz force effect on the arc plasma and weld pool metal under different arc burning modes. It was shown that in HFPC TIG welding with a given frequency, the effect of modulated current on the arc plasma is inherently non-stationary, whereas the effect on the weld pool metal is determined by the time-averaged magnitude of electromagnetic force throughout the period of current modulation. The proposed approach serves as a basis for numerical analysis of the electromagnetic forces in arc plasma and weld pool metal during DC and HFPC modes of the welding process. We established that the application of HFPC modulation promotes a greater intensity of both the gas-dynamic processes in the welding arc, thereby significantly increasing the pressure on the weld pool surface, and convective heat transfer from the most heated central region near the weld pool surface towards the weld pool bottom. Both these factors lead to an increase of the arc penetrability in the case of the HFPC mode compared with the DC mode, all other conditions being equal.

Design and manufacturing of resistive wall mode control coil of JT-60SA

Resistive wall mode control coils (RWMCs) will be installed in the vacuum vessel of JT-60SA. Since 200 °C baking of vacuum vessel on JT-60SA is performed to remove the impurity in the plasma facing components, in-vessel components must be made with heat-resistant materials such as metal and ceramic or must be cooled with water. We looked for the heat-resistant organic insulator for JT-60SA RWMC and performed the heat resistant test for several resins. However, no resin passed the test (Sukegawa et al., 2015). We again performed the heat resistant test of several organic insulator in the circumstances without air and finally found that the some Bismaleimide–Triazine (BT) resin has enough heat resistance without air. We designed the eight-turn RWMC with the BT resin. Based on this design, the specification of RWMC and power supply requirement are decided. For the design of RWMC, the finite element (FEM) analysis of electromagnetic force during disruption and thermal stress during baking and operation were performed. Manufacturing of the RWMC has already launched.

Analysis of transient electromagnetic force on end windings of 300 Mvar synchronous condenser during dynamic reactive power compensation process

The uneven distribution of renewable energy supply and demand promotes the development of high-voltage direct current transmission. As the critical reactive power compensation equipment for high voltage direct current transmission, the synchronous condenser must have a strong overload capability. One of the critical factors limiting the improvement of its overload capacity is the reliability of the end winding, which depends on the magnitude of the force on end windings during dynamic large reactive power output. Therefore, this paper proposes a coupling model of transient electromagnetic force for the high voltage direct current transmission system and the end zone of the synchronous condenser. The transient response of the synchronous condenser under different fault degrees is calculated, analyzed, and verified by experiments. Based on the current response of the synchronous condenser, the transient electromagnetic force on end windings is calculated. The distribution law of the force on end windings of the synchronous condenser under different degrees of dynamic reactive power compensation process is revealed. Further, the regions on end windings with larger force during strong overload are indicated. The optimizing fixation scheme for end windings is proposed according to the distribution features of the force, which can improve the operational reliability of end windings.

Accurate Electromagnetic Force Analysis of Offshore Wind Power Transformer Windings Based on Fractional Order Lumped Parameter Model

Accurate calculation of the electromagnetic force distribution of transformer windings under different loads and fault conditions is of great significance for transformer maintenance, condition evaluation and life prediction. Due to the influence of offshore wind power systems, offshore wind power transformers have high harmonic content and large changes in load rates, which can easily cause the coil destabilization, winding deformation or even damage because of the uneven distribution of the electromagnetic force. To improve the accuracy of electromagnetic force calculation, this paper proposes a fractional order numerical method. First, a three-dimensional axisymmetric transformer model and a symmetrical lumped parameter equivalent circuit model are established, respectively, based on field-circuit coupling. Second, the fractional order approximation of circuit components is realized by using the improved Oustaloup filter. In the fractional order model, the transformer is replaced by the lumped parameter equivalent circuit model. Third, as in the calculation process for integer order electromagnetic force, the integer order current has a large error, and the current waveform does not match the actual power frequency. The fractional order current and electromagnetic force at the 0.9 order are closer to the rated value. Finally, the effects of different load rates, three-phase short circuits and harmonic conditions are studied with the fractional order model. Compared with the traditional integer order finite element electromagnetic model, the fractional order equivalent circuit model established in this paper is more accurate and suitable for electromagnetic force calculation. The proposed method is significant for the structural design and state detection of transformers and also could be applied in the analysis of other dry-type transformers.

Analysis of electromagnetic force on wireless charging structure

Analysis of electromagnetic force on wireless charging structure

Proposal of detecting for thickness method of hot spring scale inside steel pipes using vibration

At geothermal power plants, there is a problem that hot spring water pipes are blocked by the “hot spring scale”. The hot spring water used for geothermal power generation contains calcium, sulfur, and other substances, and the solid material called the “hot spring scale” adheres to the inside of steel pipes, significantly reducing the efficiency of steam transmission. In addition, there are maintenance costs to remove the “hot spring scale” inside the steel pipes. And it is important to evaluate the thickness of the hot spring scale inside the steel pipe. In this paper, a non-destructive sensor that is evaluated the thickness of the hot spring scale inside the steel tube from the outside of the steel pipe is proposed. The proposed sensor is consisted of a permanent magnet, an alternating excitation coil and an acceleration sensor. The static magnetic field from the permanent, and eddy current inside the steel pipe are generated the vibration in the steel pipe. And the thickness of the hot spring scale is evaluated from this vibration intensity. It is shown that the thickness of hot spring scale from 0 mm to 15 mm can be inspected by this proposed method. In addition, the proposed inspection principle of this inspection method will be clarified by 3-D electromagnetic force analysis and displacement analysis.

Modelling and analysis of electromagnetic force, vibration, and noise in permanent magnet synchronous motor for electric vehicles under different working conditions considering current harmonics

AbstractThe vibration and noise of the permanent magnet synchronous motor (PMSM) is mainly caused by its electromagnetic force. Harmonic currents affect the vibration, and noise performance of PMSM by influencing its electromagnetic force. The regularity of electromagnetic force, vibration, and noise characteristics of PMSM for electric vehicles (EVs) under different working conditions influenced by the harmonic currents is studied. Firstly, the analytical model of electromagnetic force under the action of a harmonic current is derived, and the influence of harmonic currents on the electromagnetic force of PMSM is summarised. Secondly, a multi‐physical field coupled vibration, and noise calculation model considering harmonic currents is established using the finite element method, and the vibration, and noise characteristics of PMSM under different operating conditions are analysed. The results show that the harmonic currents have different patterns of influence on the vibration, and noise of the PMSM due to the different advance angles and the saturation degree of the magnetic material under different working conditions. Finally, the validity of the theoretical analysis is verified by experiments, which has academic significance for vibration, and noise reduction of PMSMs for EVs.

Comparative Study of Vibration on 10-Pole 12-Slot and 14-Pole 12-Slot PMSM Considering Tooth Modulation Effect

In this study, the electromagnetic force and vibration characteristics of 10-pole 12-slot and 14-pole 12-slot permanent magnet synchronous motors (PMSMs) are examined considering the tooth modulation effect. In contrast to the conventional electromagnetic force analysis process which considers only the radial force of the lowest spatial harmonic order, the radial and tangential forces include low and high spatial harmonic orders which can be modulated with a lower spatial harmonic order, are analyzed. Then, a structural finite element (FE) model is developed, and vibration analysis is performed by applying a modulated force and moment. In the analysis, the amplitude and phase of the modulated radial force, tangential force, and moment are considered. The vibration analysis result shows that the 10-pole 12-slot PMSM is disadvantageous with respect to vibration when compared to the 14-pole 12-slot PMSM owing to the large modulated force. Also, it is confirmed that the effect of modulated tangential force and moment cannot be neglected, and the phase difference between modulated radial, tangential force and moment is also an important factor in vibration. Finally, the two motors are fabricated, and the validity of the FE analysis results is verified using the test results.

Analysis and inhibition of radial electromagnetic force in composite magnetic coupler

AbstractA new inhibition method was proposed for the problem of harmonic of radial electromagnetic force during the operation of the composite magnetic coupler. In order to suppress its radial electromagnetic force, a radial permanent magnet rotor eccentricity method is proposed, and a three‐dimensional finite element model is established. Based on the Maxwell tensor method, the radial electromagnetic force of the composite magnetic coupler is analysed, and the mathematical expression of its radial electromagnetic force is established, Maxwell stress tensor was used to analyse the radial electromagnetic force in a composite magnetic coupler and to establish the mathematical equation for the radial electromagnetic force. In order to suppress the radial electromagnetic force, a method based on rotor eccentricity in a radial permanent magnet was proposed. A prototype of a composite magnetic coupler with a rated power of 5 kW was designed to test its output torque under load. The results showed that the simulated curve was consistent with the tested curve, with a maximum numerical error of 8.9%. The tested values of the output torque before and after eccentricity were compared, and the results showed that the output torque remained basically unchanged after the eccentric structure was adopted and that the torque pulsation was significantly reduced.

Analysis and weakening of radial electromagnetic forces in high‐speed permanent magnet motors with external rotors based on shape functions

AbstractIn this paper, a strategy of integrating direct‐drive turbine compressors with high‐speed permanent magnet external rotor motors is used to improve the problems of large footprint, low efficiency and high maintenance costs. The rotor of the motor will vibrate under the action of radial electromagnetic force when rotating, and under the action of high pressure and high speed gas, it may aggravate the rotor vibration. In the case of changing the original mechanical structure of the turbine, the vibration of the motor rotor needs to be analysed. In the paper, the radial electromagnetic force applied to the rotor is analysed. The influence of the order and size of the stator and rotor magnetic field harmonics on the size, frequency and order of the radial electromagnetic force wave is summarised. In order to weaken the radial electromagnetic force, this paper proposes a shape function about the magnetic pole size and designs a magnetic pole accordingly. The validity of the shape function was confirmed by comparing the radial electromagnetic force wave with a conventional, surface‐mounted, built‐in magnetic pole structure. Finally, based on the analysis of the rotor dynamics mode, the law of the effect of the change of the pole arc coefficient of the pole on the radial force was analysed using harmonic response, and reasonable conclusions were drawn.

Modeling and Analysis of Radial Electromagnetic Force and Vibration Characteristics Based on Deflection Dual-Stator Switched Reluctance Generator.

In this paper, a mechanical model of the deflection dual-stator switched reluctance generator (DDSRG) is developed, and the advantages of the dual-stator structure for the deflecting motion are analyzed. Secondly, the spatio-temporal and spatial distribution characteristics of the inhomogeneous electromagnetic force are derived analytically and further verified by fast Fourier transform (FFT).Thirdly, the spatial and temporal distributions of electromagnetic forces of DDSRG are calculated based on finite element software, and the distributions of electromagnetic forces under different motion states are analyzed. By combining the analysis of modal analysis and harmonic response analysis, the free mode and vibration response acceleration variation laws of the internal and external stator are determined. The results show that the order of electromagnetic forces on the stator at rated speed is mainly 8 times the fundamental frequency, and the modal vibration order is more violent in the order of 2–7. Finally, the experimental platform of DDSRG is built, and the vibration characteristics are tested to verify the validity and accuracy of the proposed simulation results.

3-D Electromagnetic Force Characteristics and Modeling of Double-Sided Air-Cored Superconducting Linear Synchronous Motor for EDS Train

Double-sided air-cored superconducting linear synchronous motors (DSAC-SLSMs) play an important role in electrodynamic suspension trains. For this type of motor, the existing magnetic field modeling method is improved in this study, and a new 3-D electromagnetic force (EMF) analysis method is proposed to analyze the influence on the 3-D EMFs when the onboard superconducting coils (SCs) have multiple degrees of freedom motions such as deviation and deflection. First, based on Biot–Savart law and Poisson’s equation of magnetic vector potential, the analytical prediction of superconducting air-gap flux density is conducted. Thus, the relationship between <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> -axis armature current and 3-D EMFs is determined. Second, the equivalent circuit of DSAC-SLSM is established, and the effects of lateral and vertical displacements of the onboard SCs on armature current are analyzed. Finally, the validity of the proposed model is verified by using the finite-element model, two static experiments, and publicly available data on the Yamanashi maglev test line, while the 3-D EMF characteristics of the motor under various conditions are analyzed in detail.

Simulation and Analysis of Internal Short Circuit Fault, Electromagnetic Forces and Thermal Analysis of Single Phase Transformer

Simulation and Analysis of Internal Short Circuit Fault, Electromagnetic Forces and Thermal Analysis of Single Phase Transformer

Modeling and analysis of electromagnetic force in interior permanent magnet synchronous motor used for electric vehicles

The accurate prediction and analysis of electromagnetic excitation source is the pre-condition for the investigation of electromagnetic vibration and noise. In this work, an analytical model for electromagnetic (EM) force calculation of interior permanent magnet synchronous motors (IPMSMs) is proposed by coupling the 2-D model in polar coordinates and the Maxwell stress tensor method (MSTM). In the modeling, the boundary conditions for solving the air-gap magnetic field are firstly simplified based on the equivalent conversion of permanent magnets (PMs). Then, the magnetic field is acquired by solving the governing equation based on the simplified boundary conditions. Finally, the EM force is obtained according to the MSTM. The effectiveness is fully verified by finite element (FE) analysis that the analytical model can be applied not only for the calculation of radial EM force of IPMSMs with/without load but also for the calculation of tangential EM force. Besides, the tangential EM force is further analyzed by 2-D Fourier decomposition, and the relationship between tangential EM force and torque fluctuation is also clarified. The results show that the radial EM force harmonics and the tangential EM force harmonics have the same spatiotemporal characteristics no matter under no-load or load. Moreover, the high-frequency components of tangential EM force harmonics with low spatial orders, which have the highest contribution to vibration and noise, are comparable to those of radial EM force harmonics. Meanwhile, the torque fluctuation of IPMSMs with/without load only comes from the zero-order tangential EM force harmonics in space.

Modelling, Calculation and Analysis of Electromagnetic Force and Vibroacoustic Behavior of Integer-Slot Permanent Magnet Synchronous Motor Considering Current Harmonics

Modelling, Calculation and Analysis of Electromagnetic Force and Vibroacoustic Behavior of Integer-Slot Permanent Magnet Synchronous Motor Considering Current Harmonics

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.