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An increasing need for fast and reliable models has led to a continuous development of Fourier-based (FB) analytical modeling. This paper presents an overview of the techniques that are currently available in FB modeling for electric machines. By coupling that overview to the most relevant literature related to the subject, an interesting starting point is provided for anyone who wants to use or improve FB models. The following seven aspects of FB models are discussed in detail: 1) the magnetic potential (scalar or vector potential); 2) the coordinate system and the solution of the partial-differential equations for each magnetic potential and for each coordinate system; 3) the way in which time dependence is accounted for; 4) the implementation of the source terms; 5) the possibilities to account for slotted structures; 6) the modeling of eccentricity; and 7) the post-processing computation of physical quantities, such as flux density, electromotive force, torque, losses, and eddy currents in conductive objects. Furthermore, this paper gives the closed form solution of the Laplace, Poisson, and Helmholtz equations in each coordinate system. In addition, this paper tackles other important features of FB models such as computational time reduction and coupling the machine model to an electric circuit. [ABSTRACT FROM AUTHOR]

The quantitative analysis of the iron loss taking magnetic hysteresis behavior into account is essential for the development of high-efficiency electric machines. In a previous paper, a novel magnetic circuit model incorporating a play model, which is one of the phenomenological models of magnetic hysteresis, was proposed. It was clear that the proposed model can calculate the hysteresis loop of a ring core with high speed and high accuracy. However, this method was applied only for the objects with simple shapes. Thus, it is necessary to extend the applicable range for the objects with more complicated shapes. This paper presents a novel reluctance network analysis (RNA) model incorporating the play model and indicates the validity of the proposed RNA model by using a three-phase-laminated-core variable inductor as an object of discussion. [ABSTRACT FROM AUTHOR]

In this paper, rotor inter-turn faults in salient-pole synchronous machines are investigated using finite-element analysis. The machine under study is a 22 MVA eight-pole hydropower generator with fractional-slot windings. Simulated faulty cases include 1, 2, 5, 10, and 20 short-circuited turns (out of 58 turns) in one rotor pole. In the electromagnetic analysis, the effect of faults on airgap flux density and radial forces is studied. Furthermore, this paper investigates online detection of inter-turn faults using spectral analysis of stator voltage or current is studied. The amplitude of fault-related harmonics is investigated at various fault severities, as well as at no-load and full-load operations. This paper also discusses the effects of damper bars, an influence of parallel circuits in the stator windings, and influence of the pole pair number. In addition, a comparison between fault-related harmonics in the case of dynamic eccentricity and rotor inter-turn faults is presented. [ABSTRACT FROM AUTHOR]

This paper addresses the measurement and calculation of unbalanced magnetic pull (UMP) in a wound rotor induction machine. A new rig for measuring UMP is presented. To our knowledge, this type of rig has not been tested before. This paper details the force calculation method and a method for splitting the UMP and torque. Wound rotor induction machines are now popular as generators in wind turbines. It is important to maintain good operation and low bearing wear, and the UMP in these machines is higher than that of the cage-rotor equivalent because the cage damps the UMP. There is little literature on the UMP in a wound rotor machine. [ABSTRACT FROM AUTHOR]

This paper presents an analytical solution of the eddy currents in the permanent magnets (PMs) in the axial flux PM synchronous machine using a coupled solution of Maxwell’s equations and electric circuit network. This is based on calculating the axial field in an accurate way on the surface of the PM. This method is able to consider the effect of armature field and slots. The eddy currents are obtained by imposing this solution on the PM which is modeled by a simple electric network. This network is composed of simple resistances and inductances. The inductances are used to model the reaction field effect of the eddy currents flowing through the PM and also the skin effect. To show this effect, the machine is excited with different sources at different speeds. In addition, a variant of the model is made that neglects the inductances, in order to show in which conditions this low-frequency approximation is acceptable. It is concluded from this paper that inclusion of the reaction field is necessary when the machine is excited by a pulsewidth modulated (PWM) current, while for a sinusoidal excitation, the reaction field effect has minor contributions to the total eddy losses. In addition, the reaction field has major influence at higher speeds rather than lower speeds for PWM injection. In conclusions, for a preliminary design, the resistance model without the reaction field computation would be enough for the calculation of the PM losses. The circuit model is also capable of obtaining the solution with PM segmentation. In this paper, different PM segments were studied from the circuit model and the finite-element (FE) model point of view. Compared with the FE model, the circuit model has the advantage of flexibility in geometrical machine parameters, less CPU time, and accurate results for the PM losses up to 10%. [ABSTRACT FROM AUTHOR]

For the safety of the wound-rotor synchronous machine (WRSM) in aircraft applications, the overvoltage at the motor terminals, electromagnetic interference (EMI) performance, and bearing currents as well as the loss analysis are the core areas to be addressed. The high-frequency (HF) modeling method of the WRSM, which has a strong relationship with all these core areas, is a very critical theme. In this paper, a measurement-based wide-frequency (WF) modeling method to characterize the impedance of the WRSM is proposed to build a straightforward correlation between fundamental models and HF parasitic circuit elements. In this paper, the voltage-behind-reactance method is applied to demonstrate the rotor-angle-dependent characters in the low-frequency domain, while the vector fitting method is used to parameterize the HF branch for high-accuracy consideration. By doing this, a WF electrical model with multistage RLC units is formed, which comprehensively considers both the saliency character of the machine and frequency range. The WF model is also compatible with the circuit-based simulation. Finally, the EMI prediction orientated simulation and experimental results are implemented on a 10 kVA WRSM prototype to verify the correctness and advantages of the proposed modeling method. [ABSTRACT FROM AUTHOR]

In this paper, the magnetic integration of resonant reset forward (RRF) converter and magnetic-thermal coupling analysis of integrated magnetic (IM) components are explored. The formulas of magnetic reluctance, winding turns, and magnetic flux density are obtained based on the equivalent magnetic circuit and minimum current pulsation scheme. Meanwhile, circuit-field coupling model of RRF converter and magnetic-thermal coupling model of IM components are built with the finite-element analysis (FEA) method. The simulation results illustrate that the core of the integrated RRF converter works in an unsaturated condition, the temperature rise of IM components is about 20 °C, and the integrated RRF converter has almost the same power efficiency as the conventional discrete RRF converter. Furthermore, hardware prototypes are fabricated and tested to verify the simulation accuracy and design validity. The conclusion of this paper will provide a reference for improving magnetic integration efficiency in the future design of RRF converter. [ABSTRACT FROM AUTHOR]

Incipient stator winding fault in permanent magnet synchronous wind generators (PMSWGs) is very difficult to be detected as the fault generated variations in terminal electrical parameters are very weak and chaotic. This paper simulates the incipient stator winding faults at different degree of insulation degradation of one turn in the winding of a PMSWG. Cosimulation method by combining finite element model and external circuits is used. Hilbert–Huang transformation is applied to detect the very early stage fault in interturn insulation by analyzing the stator current. Detection results show that the minimum detectable severity degree of interturn fault in this paper is 0.1488%, which is much better than the best record in the literature. [ABSTRACT FROM AUTHOR]

Dynamic operational behavior (DOB) of electrical machines can cause effects that are difficult to describe and understand. The short-circuit behavior (SCB) in particular is a dangerous DOB for machine and human. It could destroy the machine itself and cause heavy damage to the power supply unit and mechanical coupling components. Analytical calculation of the SCB is simplified and thus not highly accurate. Therefore, the finite element method simulation of the SCB is an important tool for understanding these effects without the danger of damaging the machine by experiments. In this paper, a suitable field formulation, modeling details, and simulation methods for dynamic analysis of synchronous machines are presented in detail. In particular, the accuracy of 2-D and 3-D transient electromagnetic simulations is analyzed by comparison against the available measurements performed on a chosen testing salient pole synchronous machine under the conditions of three-phase, two-phase, and single-phase short circuit. [ABSTRACT FROM AUTHOR]

This paper presents the magnetic and electrical equivalent circuits of a hysteresis interior permanent magnet (IPM) motor. A hysteresis IPM motor is a solid rotor hybrid synchronous motor combining hysteresis phenomena and permanent excitation in the rotor. When installed in thousands of feet under the sea to drive an electric submersible pump (ESP), it can self-start the ESP without the need of any position sensors, and can improve the efficiency, the performance, and the reliability of the ESP. In this paper, equivalent circuit models are used to predict the transient run-up responses of a 2.5 kW prototype hysteresis IPM motor. Analysis results are compared with 2-D finite-element analysis (FEA) results as well as experimental results. There exists a reasonably close agreement between analytical, FEA, and experimental results, which validates the accuracy of the equivalent circuit models of a hysteresis IPM motor. [ABSTRACT FROM PUBLISHER]

Bidirectional inductive power transfer (BIPT) systems enable power transfer between stationary electricity sources and movable consumers in each direction through electromagnetic coupling. Due to its complexity, a mathematical model is required to design and to control these systems. This paper presents the mathematical analysis and the frequency-domain analysis for two different compensated (series–series and parallel–parallel) BIPT systems. This paper contains the modeling procedure of the BIPT system’s coils in the frequency domain. The prediction of its equivalent circuit values, magnetic stray field values, and coil positioning tolerance are determined as well using the JMAG field simulation software. Furthermore, the transmission characteristics and the efficiency of the two compensation topologies are discussed. [ABSTRACT FROM AUTHOR]

Traditionally, flux distributions in transformer cores are modeled as a 2-D problem. However, experimental studies indicate that 3-D models are needed. The main reason is that limbs of circular cross section are combined with roughly semi-circular yokes. At the joints, this yields shifts of overlap regions as a reason of significant (off-plane) normal direction (ND) induction B\mathrm {ND} . This paper reports a first corresponding 3-D modeling of a two-package one-phase core with the consideration of non-linear characteristics of material. For corners, the so-called critical induction B\mathrm {CRIT} of joints—as arising close to 1.4 T—is considered. Two instants of the cycle of global magnetization are addressed, i.e., B\mathrm {GL} = 1.7 T for normal operation and 1.9 T as a value that may arise for dc bias. For 1.7 T, the results indicate strong inhomogeneity, in particular in the wide main package of the core. On the other hand, 1.9 T is characterized by distinct homogenization. As 3-D effects, the cycle of magnetization involves distinct changes of flux in ND, with values up to more than 0.2 T. Half-cycle saturation is indicated especially for inner (window-sided) corner regions. The corresponding consequences on local magnetostriction (MS) values are over-proportional due to the complex dependence of strain $\lambda$ and induction. The so-called butterfly curve is dynamically passed beyond the turn point and even into its positive range. In particular, this yields distinct distortion of $\lambda$ , which can be assumed as a source of over-proportional rises of A-weighted noise. Apart from MS, further enhancement is to be expected from inter-laminar forces. [ABSTRACT FROM AUTHOR]

As a reliable and non-destructive technique, frequency response analysis (FRA) has been widely recognized for transformer winding deformation detection and assessment. In this paper, frequency response functions (FRFs) are obtained by two different FRA measurement connection ways, namely, end-to-end voltage ratio (EE) and transfer voltage (TF) ratio measurements. At the same time, according to the two ways, sensitivities of the FRFs to electrical parameters of the equivalent circuit model of the transformer winding are investigated. Based on Tellegen theorem, adjoint network method is derived to calculate the values of the sensitivities of FRFs to electrical parameters. Meanwhile, the sensitivity characteristics of circuit parameters are studied. In addition, by comparing the sensitivity results of the two ways, the variation laws of the sensitivities under the two different connection approaches are determined. Besides, this paper can provide a new and objective method to interpret the FRA results and give us a better understanding how much the parameter variations can influence the FRA measurement results. [ABSTRACT FROM AUTHOR]

High thermal stability, a fast switching time, and a low switching current are key characteristics of merit for realizing gigabit-class magnetic random access memory (MRAM). Especially, the switching current needs to be reduced significantly for creating high-density MRAM. In order to realize these necessary features, a number of magnetic tunnel junction (MTJ) structures have been proposed. A previous study of ours led to the proposal of a novel Curie-temperature-controlled hybrid thermo-magnetic structure for MRAM, for the purpose of improving these advantageous properties. This paper presents an analysis of the switching time and switching current by using micromagnetic simulation techniques for comparing our structures with various MTJ structures that have been proposed recently. We confirm that our novel structure can improve the switching characteristics of MRAM. The results of our analysis revealed that a 44% lower switching current and a 32% faster switching time can be achieved compared with the conventional structure. [ABSTRACT FROM AUTHOR]

This paper presents an improved magnetic circuit (MC) model considering the leakage, cross coupling, and saturation effects for the performance analysis of an integrated 3 degrees of freedom magnetic bearing (3-DOF MB). Compared with the conventional MC model, this paper analyzes the permanent-magnet bias field, radial and axial control current fields together. By using this improved MC model, it reveals the cross-coupling effect between radial and axial directions in such an integrated 3-DOF MB. The stiffnesses of radial force are significantly influenced by the axial control current, while the stiffnesses of the axial force are independent of the radial control current. Its accuracy is verified by the 3-D finite-element method. [ABSTRACT FROM AUTHOR]

This paper introduces a three-phase reversible transformer model for the study of low-frequency transients. The model topology is obtained from the direct application of the principle of duality by drawing basic circuit elements on top of the transformer frame. The model parameters are obtained from terminal and physical size measurements as well as the characteristics of the iron core. The implementation of the model is based on standard drag-and-drop circuit elements available in electric circuit simulation programs. The model is validated with inrush current and normal open circuit laboratory measurements. The main advantage of this model is that the parameters remain the same for the simulation of different operating conditions from all terminals. This is true for transients involving deep saturation, normal loading operation, or open circuit. [ABSTRACT FROM AUTHOR]

The stray load losses in electrical machines represent a non-negligible contribution of the total losses and are a key point for an accurate evaluation of the energy efficiency of the considered device. In this paper, a methodology using the 3-D finite-element (FE) modeling approach and a posteriori loss calculation is presented for the estimation of the stray load losses. The case of a cage induction motor is investigated, and results are compared with the experiment. The simulation is performed at different load conditions using a 3-D FE model with external circuit coupling. [ABSTRACT FROM AUTHOR]

Proper generalized decomposition (PGD) is a recently developed model-order reduction method based on the use of variable-separated representations. In this paper, space variable-separated PGD is applied on the 3-D capacitance extraction of interconnects in integrated circuits to reduce its computational complexity. To make the PGD solver feasible, the complex boundary conditions are simplified by a characteristic function technique. 3-D singular-value decomposition of the coefficient functions is avoided by using a reformulated PGD algorithm, and therefore, the proposed method can effectively deal with problems with inhomogeneous dielectric layers and dummy fills. Numerical examples are given to verify the method. [ABSTRACT FROM AUTHOR]

Domain wall nanomagnet (DWNM)-based devices have been extensively studied as a promising alternative to the conventional CMOS technology in both the memory and logic implementations due to their non-volatility, near-zero standby power, and high integration density characteristics. In this paper, we leverage a physics-based model of a DWNM device to design a highly scalable current-mode majority gate to achieve a novel one bit full-adder (FA) circuit. The modeled DWNM specifications are calibrated with the experimentally measured data. The functionality of the proposed DWNM-based FA (DWNM-FA) is verified using a SPICE circuit simulator. The detailed analysis and the calculations have been performed to realize the proposed DWNM-FA delay and power consumption corresponding to the various induced input currents at different operating temperatures. The power-delay product of DWNM-FA is examined to tune the operation within the optimum induced input current region to obtain desired power-delay requirements over a range of 200 \mu \textA to 1 mA at temperatures from 298 to 378 K. Finally, the comparison results exhibit 52% and 49% area improvement as well as 41% and 31% improvement in device count complexity over CMOS-based and magnetic tunnel junction-based FA designs, respectively. [ABSTRACT FROM PUBLISHER]

This paper reports on a strongly physics-based minimal circuit model for polycrystalline cores, such as ferrites, including dimensional resonance (DR). The models and main properties of DR and hysteresis are recalled, a circuit model is described that incorporates the various phenomena, and it is mentioned how its parameters are extracted by broadband linear response and low-frequency nonlinear measurements. Finally, the simulations are validated with measurements for a specific example. The model turns out to predict accurately the magnetic behavior in the high-frequency nonlinear region. [ABSTRACT FROM AUTHOR]

The grid power distribution network (PDN) is an essential component in electronic packages to provide the dc power to circuits. In this paper, an integral equation hybrid method is proposed for the efficient calculation of the impedance of the complex grid PDN. First, the original 3-D grid PDN is reduced to a simple 2-D plane PDN. Both of them have the same input and mutual parasitic impedances. After that, this equivalent plane PDN is solved by using the 2-D integral equation method to consider its arbitrary shape. By comparing between the obtained impedances from the proposed method, full-wave method, and measurement, the accuracy and efficiency of the proposed method is verified. The proposed method provides a simple and useful electronics design automation tool for the power integrity analysis of complex circuits. [ABSTRACT FROM AUTHOR]

This paper presents a 3-D magnetic equivalent circuit (MEC) network that integrates the hysteresis model for the analysis of the axial field flux-switching (AFFS) memory (AFFSM) machine. Similar to finite element method, meshing is used to subdivide the model into smaller domains called elements, over which a set of element equations and a reluctance network equation are built. Newton–Raphson method is adopted to handle the nonlinear problems. The fixed-point technique is introduced to cope with the problem involving hysteresis. The proposed method is capable of predicting the operation of the low coercive force permanent magnet during flux regulation and the electromagnetic field distribution of the machine. Finally, the proposed 3-D MEC method is implemented for analysis of the AFFSM machine. MEC results are compared with 3-D finite element analysis and experimental results. The results show that the proposed method offers reasonable accuracy with moderate computational effort. [ABSTRACT FROM AUTHOR]

This paper investigates the effectiveness of the Cauer circuit modeling for dynamic hysteretic property in iron loss analyses of rotating machines. We apply the method to an interior permanent magnet synchronous motors fed by pulsewidth modulation inverter and compare their performance with a conventional iron loss estimation method based on 1-D finite-element analyses. As a result, almost the same iron loss is obtained by using the Cauer circuit modeling with lower computational cost. [ABSTRACT FROM AUTHOR]

The Cauer ladder network (CLN) method provides an efficient representation of eddy-current fields. This paper proposes a reformulation of the CLN method that considers expansion points using the magnetic/current vector potential. To cover a wide range of frequencies, the expansion point may be changed at a later stage of the network. Only a few stages of the ladder network are required for the eddy-current field to be reconstructed accurately around the target frequency using the expansion points. [ABSTRACT FROM AUTHOR]

In this paper, one proposes a model-assisted probability of detection approach to study the reliability of detecting special defects. The approach is based on a 3-D finite-element T– $\Omega $ formulation with circuit coupling. This model is then applied to calculate performances of induction thermography method to detect thin open cracks in vessel reactor shell in nuclear installation. [ABSTRACT FROM AUTHOR]

Nowadays, the miniaturization of the passive components is the major challenge in the better integration of electronic circuits in portable devices. This paper presents the simulation, the modeling, the manufacturing, and the characterization of a face to face transformer where conductors are buried in the magnetic layer and where the transformer’s primary and secondary windings are turned in the plane by 45°. The buried conductors allow the inductor magnetizing to be increased by a ratio of 50%. The turn of the transformer’s primary and secondary windings allows the capacitance coupling to be decreased by a ratio of 100%. Simulations are made by using the high-frequency structural simulator, which is 3-D finite-element software. Measurements are performed for frequencies ranging from 40 Hz to 300 MHz by an impedance meter and a vector network analyzer. Good consistency between the simulation and measurement is obtained. [ABSTRACT FROM AUTHOR]

In this paper, a stabilized reduced-order model based on the gappy proper orthogonal decomposition (POD) technique is applied to an eddy-current problem with the non-linear material property. A classical magnetodynamic finite element formulation based on the magnetic vector potential is used as reference and starting point to build up the reduced models. The computational complexity of the non-linear problem might be reduced by the discrete empirical interpolation method-POD technique, but the eddy current effects may make this method unstable. In this paper, we propose an approach which is similar to the gappy method to successfully overcome this instability problem, while keeping the computational cost (time and memory) low. [ABSTRACT FROM AUTHOR]

Based on the analysis of the defects of the traditional methods for determining the equivalent circuit parameters of three-phase integrated transformers by single-phase excitation, an expression method of equivalent circuit parameters and their determination approach based on three-phase simultaneous excitation are presented in this paper. The parameters are expressed in terms of the phase of the excitation source, and the value of parameters is determined by calculating the reluctance of core segments based on the finite element method simulations. Then, the electric circuit parameters are obtained by converting the magnetic circuit into the electric circuit. This kind of electric circuit model is suitable for analyzing the problems of deep saturation of transformers and the concerning power grid problems. [ABSTRACT FROM AUTHOR]

Transcranial magnetic stimulation (TMS) is a non-invasive, safe, effective, and food and drug administration approved treatment for major depressive disorder. TMS relies on time-varying magnetic fields to induce an electric field in the brain, resulting in depolarization or hyperpolarization of the neurons. Recently, there has been extensive research to improve the magnetic coil design, effectiveness of TMS treatment, and improvement in the computer modeling of human brains, yet little development is reported on the TMS pulse generators and coil design for small animals. TMS pulse generators, or stimulators, are the circuits which provides pulse current to drive the inductive coils (TMS coils), used to generate time-varying magnetic fields. Commercial TMS stimulators are expensive and have limitations of using standard and non-customizable coils. These stimulators do not support small inductive loads, which require high-current capabilities. Furthermore, the commercial animal coil stimulates the entire body of a mouse, as they are designed for large animals. In this paper, the authors present the design of a small sized TMS stimulator and a focused coil for the application on small animals such as mice. The proposed TMS stimulator will have the potential of handling small inductive loads enabling stimulation of specific regions within the mouse brain. [ABSTRACT FROM AUTHOR]

This paper presents a 2-D hybrid analytical modeling method for the analysis of the magnetostatic field distribution with the capability of including nonlinear materials. The model combines Fourier modeling, which is accurate and fast, with meshed magnetic equivalent circuits that have unique permeability in mesh elements and, therefore, can model local saturation. To present the diverse applicability of the proposed method, it is applied to a linear machine with permanent magnet excitation and a rotary machine with current excitation. Magnetic field calculations are compared with finite-element analysis (FEA) with good agreement. [ABSTRACT FROM AUTHOR]

This paper presents different methods to determine the parameters for the equivalent electrical circuit model of a high-frequency planar transformer. The first method is implemented in the circuit simulation software utilizing a 1-D electromagnetic analysis. The second method uses a 3-D electromagnetic analysis and is implemented in a finite-element analysis software. The third method is a differential evolution (DE)-based algorithm using the experimental transformer data. The first two methods are useful in the design stage to predict the performance of a planar transformer, while the third one can be applied to validate the design. The performance and accuracy of the three methods are assessed by comparing each method’s parameter estimate of an actual planar transformer. The comparison showed that the predictions of magnetizing inductance by the two numerical analyses are accurate and comparable with that of the DE-based estimation method. However, the series resistance and leakage inductance determined by the DE algorithm tend to be higher, as predicted by the two numerical methods, due to the nonconsideration of the measuring leads impedance in the numerical models. [ABSTRACT FROM AUTHOR]

Most investigations of all spin logic (ASL) have been based on the monodomain approximation of magnetization switching. The sensitive and stochastic nature of spin transfer torque (STT) switching creates pressing requirements for analyzing ASL from a micromagnetic perspective also. Hence, in this paper, ASL is studied from a micromagnetic perspective by developing a simulation framework that can capture diffusive spin transport. The spin transport model is calibrated from the existing experimental results on nonlocal spin valve measurements. Then, using this framework, STT switching is studied for input–output nanomagnets with in-plane and perpendicular magnetic anisotropy for ASL devices (ASLDs). Precisely defined architecture and design constraints for such input–output nanomagnets are presented. Further, a previously proposed switching mechanism by driving the nanomagnet into a metastable state is also incorporated into micromagnetic framework. Using the aforementioned mechanism, the critical current required for STT switching can be reduced to as low as 20 $\mu $ A. Moreover, the graphene channel ASLD using tunnel contact at the injector is demonstrated for copy and invert logic operations. [ABSTRACT FROM AUTHOR]

Multiphase brushless dc (BLDC) machines are implemented in electric and hybrid electric vehicle applications due to their high torque/power density, good fault tolerance capability, and low torque ripple. Moreover, the per-phase converter rating can be reduced by increasing the phase number. However, the number of magnetic couplings between phases increases with the phase number, and these magnetic couplings can have an important influence on the machine performance. Therefore, they need to be considered in simulation models and their effect should be considered in control algorithms. Accordingly, the objective of this paper is to analyze the effect of magnetic phase couplings on the performance of multiphase BLDC machines with an overlapping phase winding configuration. First, a detailed electric machine model, in which the machine parameters that are determined by 2-D finite-element method analysis are implemented, is developed. Using this model, the influence of mutual inductances on phase current characteristics with pulse amplitude modulation (PAM) and pulsewidth modulation (PWM) controls is investigated. In addition, a novel PAM-based control strategy, in which the effect of phase mutual inductances is considered, is proposed and analyzed. After demonstrating the influence of mutual inductances on phase current characteristics, the dependence of mutual inductances on the winding configuration is studied. Finally, experimental results with the PAM control and the new PAM-based control are used to validate the simulation results. [ABSTRACT FROM AUTHOR]

Thermal analysis is an important issue in machine design which allows to have a knowledge of the machine temperature rise. This paper presents the thermal analysis, modeling, and experiments of a linear-switched reluctance machine (LSRM) with toroidally wound mover and segmental structure. First, a 3-D heat flow model with the homogenized region for the presented LSRM is established using the thermal equivalent circuit. The equivalent thermal resistance of the model is developed together with the nodes forming of the thermal resistance network. The thermal identification to each component such as windings and core steel is performed. Then both the numerical 2-D and 3-D heat flow model for the presented LSRM are established by finite-element analysis which can give the detailed temperature distribution of the entire machine. At last, the actual experiment on a prototype is carried out, validating the accuracy, and feasibility of the thermal equivalent model above. [ABSTRACT FROM AUTHOR]

This paper used a finite-element magnetic field analysis (FEA) to investigate the instantaneous and average power in a single phase transformer and a three-phase rotating machine. We examined the influence of the hysteretic properties of the magnetic materials on the instantaneous power in FEA using the isotropic vector play model. We applied post-correction to estimate the accuracy of the average power from their equivalent circuits. [ABSTRACT FROM AUTHOR]

The block incomplete-Cholesky (IC) preconditioner is often used for parallel preconditioner in finite-element method (FEM) supported by distributed computing. When many thin elements are included in an analyzed mesh such as magnetic shielding, the convergence characteristic of preconditioned conjugate gradient method would be deteriorated. At that time, IC preconditioner with fill-in makes the convergence characteristic of linear solver much better. This paper demonstrates the validity of block IC with fill-in on linear systems arising in FEM with many flat elements. First, the ability to improve the convergence property using the fill-in strategy is verified by the simulation of magnetic shielding. Next, the parallelization performance of block IC with fill-in is illustrated by using finite-element mesh of laminated core model and induction heating cooker. [ABSTRACT FROM AUTHOR]

Electromagnetic (EM) field simulation plays a key role in the design of magnetic resonance imaging radio frequency (RF) coils. However, the values of the components in tuning and matching circuits often need to be iterated repeatedly in the conventional simulation method in order to achieve optimal scattering parameters. This leads to a time-consuming optimization to tune and match RF coils, particularly dual-tuned coils that are comprised of multiple lumped elements. A method combining EM field simulation and circuit simulation was employed in this paper, which can dramatically improve simulation efficiency for the optimization of the values of the lumped elements and corresponding EM field distribution. A systematical theoretical analysis of the co-simulation method was presented. To validate the accuracy and efficiency of the co-simulation method, a comparison study was conducted between the conventional simulation and the proposed co-simulation approaches. [ABSTRACT FROM AUTHOR]

This paper deals with the harmonic-balance (HB) finite-element (FE) analysis of a multi-turn winding device coupled to electrical circuits comprising nonlinear components. The eddy-current effects in the windings are accounted for via a frequency-dependent reluctivity and impedance determined with a homogenization technique. The proposed multi-frequency approach is validated through a single-phase four-diode rectifier with an axisymmetric FE model of an inductor. The system of nonlinear algebraic equations is solved by means of the Newton–Raphson method. The HB results are validated with classical time-stepping simulations. The computational cost is briefly discussed. [ABSTRACT FROM AUTHOR]

In this paper, the multi-turn coil used in a wireless power transfer (WPT) device is modeled as a uniform material using the homogenization method to consider the proximity effect. By fitting the coil impedance to the numerical results, the Cauer equivalent circuit of the multi-turn coil is synthesized for the design and optimization of the power circuits in the WPT device. It is shown that the results obtained from the equivalent circuit and measurement are in good agreement. Moreover, the impedance of a flat WPT coil composed of a Litz wire is shown to be accurately evaluated by the proposed method when the contribution of capacitance is negligible. [ABSTRACT FROM AUTHOR]

The radiated electromagnetic interference (EMI) behavior may have a negative impact on the machining accuracy of grinding machines. Therefore, this paper focuses on the radiated EMI generated by an ultra-precision pulsewidth modulation permanent-magnet synchronous motor (PMSM) drive system. The excitation for the radiated EMI model, the common-mode (CM) ground current at the output terminal of the converter, is obtained by simulating its conducted EMI model. The reasonable simplified FE models for the converter frame, the shielded power cable, and the motor frame are established. In addition, an equivalent circuit macro model of the CM impedance of the three-phase PMSM windings is obtained by using impedance measurements, the vector fitting method, and the fast residue perturbation method. Finally, the 3-D time harmonic field-circuit coupled finite-element method is employed to evaluate the radiated EMI. [ABSTRACT FROM AUTHOR]

Significant stray magnetic field exists around the inductive-power-transfer (IPT) coils owning to the large gap between transmitter and receiver. In this paper, the field is attenuated by controlling the phases of windings’ currents. The relationship between magnetic field and windings’ currents is analyzed according to the diagrams of phasors. The dual-side-controlled converter is used for circuit realization, in which the inverter and rectifier with MOSFETs bridges are implemented on both the transmitter side and receiver side. The pulsewidths of the voltages for the inverter and rectifier control the currents magnitudes, whereas the phases of the voltages control the currents phases. The effectiveness of field attenuation with this method was verified in both simulation and experiment, for the IPT system with series-series compensation. The stray magnetic field was reduced by up to 30% when the phase difference is 50° between transmitter current and receiver current, compared to the conventional case with passive rectifier when the phase difference is 90°. The increase of winding losses is also analyzed. [ABSTRACT FROM PUBLISHER]

Magnetic-valve controllable reactor (MCR) has been widely applied in many kinds of industries, such as power systems and ferrous metallurgy. As electrical equipment, MCR can adjust its reactance smoothly and continuously, which has advantages like low dissipation and maintenance costs, high reliability. In this paper, a precise 2-D field-circuit coupling model of MCR is established by the finite element analysis software-ANSYS, and then the analysis of the harmonic characteristics of this model is presented in detail. Compared with the conventional numeric method, the proposed method could obtain more practical and accurate results and also has the ability to analyze electromagnetic field. Meanwhile, an experimental platform of a 2200 VA/380 V MCR is built. This paper provides detailed harmonic characteristics analysis of simulation and experiment. The simulation and experimental results verify that the proposed method is more accurate than using conventional ways. [ABSTRACT FROM PUBLISHER]

High-temperature superconducting quantum interference devices (HTS SQUIDs) have been developed as an extremely sensitive magnetic sensor. The HTS SQUIDs are required to have high robustness with respect to the magnetic noise for stable operation in an unshielded environment and also reduced cost to widen the application range. It is, therefore, necessary to clarify the quantum magnetic behavior of the HTS SQUID. However, a simulation tool, which can consider the quantum magnetic behavior, has not been developed yet. In this paper, an equivalent circuit of a Josephson junction comprising the HTS SQUID is more properly considered to represent the quantum behavior. It can consider the ac and dc Josephson effect. The obtained results are compared with an ordinary simulation using a simplified circuit model, and the results agree well with each other. Using the proposed simulation method instead of the ordinary simulation, the current path is more accurately simulated, so this new method will be used to evaluate the robustness of the SQUID. [ABSTRACT FROM PUBLISHER]

This paper presents the analysis of open circuit performance of a permanent magnet linear machine using a new hybrid analytical model (HAM). The goal is to show the capabilities offered by this new modeling approach. The new HAM is based on a strong coupling of magnetic equivalent circuits method and analytical models. The analytical model, based on the formal solution of Maxwell’s equations, is established because of the separation of variables method. The open circuit performance are: 1) cogging force; 2) electromotive force; and 3) open circuit iron loss, obtained from the HAM are compared with corresponding results obtained from a finite-element analysis. A very good agreement has been obtained. [ABSTRACT FROM PUBLISHER]

This paper deals with the evaluation of various dynamic models for modeling of three-limb core power transformers. Due to the specific construction of such transformers, the magnetic fluxes in individual core limbs are interdependent. For applications, such as simulations and testing protection devices and algorithms, adequate prediction of inrush currents waveforms is crucial and indispensable. In this paper, various different dynamic models are tested where the limitations of standard models that are available in commercial program packages are pointed out. Two groups of models are evaluated separately: standard three-phase models composed of three-single phase transformer models and advanced three-phase models, where the topology of the magnetic circuit is considered. Furthermore, in both transformer model groups, three different material descriptions are evaluated, where linear, non-linear, and hysteretic material properties are considered. The comparison between measured and calculated waveforms of inrush currents is used to evaluate individual models. The comparison of evaluated models shows that standard dynamic models cannot provide proper waveforms of inrush currents regardless of which magnetically non-linear behavior of the iron core is considered. For adequate modeling of discussed transformers the consideration of the topology of the magnetic circuit is crucial. [ABSTRACT FROM AUTHOR]

This paper analyzes the dynamic characteristics of interior permanent magnet synchronous motor (IPMSM), taking in to account the outer disturbance to a motor system. Based on the analyzed results from electromagnetic field characteristic analysis, the equivalent circuit parameters are derived, and the modeling of both IPMSM and controller system is also performed to predict its operating characteristics. In particular, in our simulation, the dynamic characteristics according to inductance variation by an outer disturbance are specifically analyzed, and all the simulation results are experimentally validated showing well corresponded results. [ABSTRACT FROM AUTHOR]

This paper presents a time-domain equivalent circuit approach for analyzing lightning-generated electromagnetic transients in modern buildings. The building is represented by a wire-plate structure and is modeled by the internal impedance and external inductance of current cells and the coefficients of potential cells. A vector-fitting technique is applied for modeling frequency-varying internal impedance for time-domain simulation. With this unique formulation, the number of unknown variables is reduced, and computational efficiency is improved significantly. Finally, lightning-generated impulse magnetic fields and voltages within a building are evaluated. [ABSTRACT FROM AUTHOR]

In this paper, a new method for generating high-efficiency vortex beam carrying orbital angular momentum (OAM) mode is proposed based on the miniaturized element frequency selective surfaces (MEFSS) in the microwave region. The unit cell is a class of sub-wavelength periodic structure, which is composed of non-resonant elements with a low profile. A flat metalens is designed to control the wavefront of the propagating electromagnetic waves based on different phase responses of eight kinds of MEFSS unit cells. Under linearly-polarized normal incidence, a vortex beam carrying OAM mode with a topological charge of 1 is excited. The measurement results are in good agreement with the theoretical prediction and full-wave simulation. The proposed method shows great potential applications in generating OAM mode with high efficiency at microwave frequencies. [ABSTRACT FROM AUTHOR]

A scalable, broadband, and physics-based compact model for on-chip spiral inductors with rectangular outline shape is demonstrated for the first time in this paper. A simple dc inductance model is developed based on the current sheet approximation. The reduction in inductance due to the flow of eddy current in a back metal plate is considered using the method of images. A three-ladder network is shown to be sufficient to accurately model skin effect caused due to the magnetic field setup at high frequencies. Geometry-dependent expression suitable for rectangular cross-sectional metal strips is presented to predict the proximity effect. Physics-based expression for the substrate capacitance is derived. The proposed model is also shown to have a good correlation in the presence of a patterned ground shield. The proposed model is verified across CMOS process parameters that affect the inductor performance, such as metal thickness, substrate resistivity, and substrate thickness. Furthermore, model accuracy is also validated across design parameters such as spiral width, spacing between turns, number of turns, and diameter. The model is shown to have a good agreement with both EM simulations and measurements. [ABSTRACT FROM AUTHOR]

High endurance, high speed, scalability, low voltage, and CMOS-compatibility are the ideal attributes of memories that any integrated circuit designer dreams about. Adding non-volatility to all these features makes the magnetic tunnel junctions (MTJs) an ultimate candidate to efficiently build a hybrid MTJ/CMOS technology. Two-terminal MTJs based on spin-transfer torque (STT) switching have been intensively investigated in literature with a variety of model proposals. Despite the attractive potential of the STT devices, the issue of the common writing/reading path decreases their reliability dramatically. A three-terminal MTJ based on the spin-orbit torque (SOT) approach represents a pioneering way to triumph over current two-terminal MTJs by separating the reading and the writing paths. In this paper, we introduce the first compact model, which describes the SOT-MTJ device based on recently fabricated samples. The model has been developed in Verilog-A language, implemented on Cadence Virtuoso platform and validated with Spectre simulator. For optimized simulation accuracy, many experimental parameters are included in this model. Simulations prove the capability of the model to be efficiently used to design hybrid MTJ/CMOS circuits. Innovative logic circuits based on the SOT-MTJ device, modeled in this paper, are already in progress. [ABSTRACT FROM PUBLISHER]