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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]

In this paper, a new behavioral modeling approach for magneto-static hysteresis is presented. Many accurate models are currently available, but none of them seems to be able to correctly reproduce all the possible $B$ – $H$ paths with low computational cost. By contrast, the approach proposed in this paper is based on simple functions, which do not require calculus to be involved, thus assuring a very good efficiency in the algorithm. In addition, the proposed method enables initial magnetization curves, symmetric loops, minor loops, normal curves, and reversal curves of any order to be reproduced, as demonstrated through the pertinent results provided in this paper. A model example based on the proposed modeling technique is also introduced and used as inductor core, in order to simulate an $LR$ series circuit. Finally, the model ability to emulate hysteretic inductors is proved by the satisfactory agreement achieved when comparing the measured and simulated results. [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]

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]

In this paper, a fast H(M) magnetostatic hysteresis model is presented, tested, and used in Simulink and partial element equivalent circuit (PEEC) environments. The model is primarily designed to achieve full compatibility with the current 3-D PEEC formalism for nonlinear isotropic magnetic materials, compatibility not met by any direct model. The capabilities of the proposed model are shown in stand-alone configuration and as a core of circuit components within the Simulink environment. Its effectiveness in the 3-D PEEC formulation is then demonstrated. [ABSTRACT FROM AUTHOR]

To achieve high-performance computing of a microwave simulation with small-size hardware and low power consumption, the authors have been working on the development of a dataflow architecture finite difference time domain (FDTD) dedicated computer. One of the biggest problems of the method of the dedicated computer for being used in practical applications is flexible design for various kinds of numerical models. The previously developed FDTD machine was designed to deal with arbitrary 3-D numerical model, any dielectric materials, and PML distributions by the same hardware circuit. This paper proposes a modified architecture of the FDTD dedicated computer for the microwave simulation in dispersive materials. [ABSTRACT FROM AUTHOR]

Among the model-order reduction techniques, the proper orthogonal decomposition (POD) has shown its efficiency to solve magnetostatic and magnetoquasistatic problems in the time domain. However, the POD is intrusive in the sense that it requires the extraction of the matrix system of the full model to build the reduced model. To avoid this extraction, nonintrusive approaches like the data-driven (DD) methods enable to approximate the reduced model without the access to the full matrix system. In this paper, the DD-POD method is applied to build a low-dimensional system to solve a magnetostatic problem coupled with electric circuit equations. [ABSTRACT FROM AUTHOR]

In this paper, a broadband equivalent node-to-node admittance functions (NAFs) model for shielded power cables are presented aiming at the direct time-domain simulation. The finite-element method is employed to obtain the frequency-dependent per-unit-length resistances, self- and mutual-inductances, and the self- and mutual-capacitances of the power cables. The matrix rational approximations are then applied to obtain the rational model (in pole-residue form) of the terminal admittance matrix of the multi-conductor transmission line (MTL) model. Next, the numerical stability of the rational model is guaranteed by the terminal (port) passivity enforcement technique. The circuit representation of the equivalent NAFs of the full cable with the length of interest can be synthesized based on the pole-residue description. It is validated by comparing the frequency response with the one computed by applying the original MTL model. [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]

The Proper Orthogonal Decomposition (POD) combined with the (Discrete) Empirical Interpolation Method (DEIM) can be used to reduce the computation time of the solution of a Finite Element (FE) model. However, it can lead to numerical instabilities. To increase the robustness, the POD_DEIM model must be constructed by preserving the structure of the full FE model. In this paper, the structure preserving is applied for different potential formulations used to solve electromagnetic problems. [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 a laboratory test procedure to determine the parameters of the inverse hysteresis model (IHM) applicable to single-phase toroidal transformer low-frequency modeling. The model parameters are obtained through a fitting procedure of the history-independent IHM of a series of open-circuit experiments and waveform recordings. These experiments can be easily executed during the transformer acceptance testing at the factory laboratory. The performance of the model is verified under various operational conditions, such as sinusoidal excitation, varied frequencies and voltages, and non-sinusoidal excitations. The results show that the model performs very well under all tested conditions giving great confidence that the proposed method can be used for parameter determination. [ABSTRACT FROM PUBLISHER]

Electrical machines with stranded random windings often suffer from considerable circulating current losses. These losses have been poorly studied because of the difficulty and computational cost of modeling stranded windings, and the stochastic nature of the problem due to the uncertain positions of the strands. This paper proposes two methods to model random stranded windings of arbitrary complexity. First, a circuit model considering the entire main flux path is presented, and some practical implementation considerations are discussed. Second, a computationally efficient finite-element approach based on non-conforming meshing is presented. Finally, a method is proposed to model the random packing process of strands within a slot, without any remeshing or inductance recalculation required. The proposed methods are then compared with special no-rotor measurement data of a large number of high-speed induction machines, and good agreement is observed. [ABSTRACT FROM PUBLISHER]

To study a multirate system, each subsystem can be solved by a dedicated software with respect to the physical problem and the time constant. Then, the problem is the coupling of the solutions of the subsystems. The waveform relaxation method (WRM) seems to be an interesting solution for the coupling, but until now, it has been mainly applied on academic examples. In this paper, the WRM is applied to perform the coupling of a controlled rectifier and a non-linear finite element model of a transformer. [ABSTRACT FROM AUTHOR]

Among the model order reduction techniques, the proper generalized decomposition (PGD) has shown its efficiency to solve static and quasistatic problems in the time domain. However, the introduction of non-linearity due to ferromagnetic materials, for example, has never been addressed. In this paper, the PGD technique combined with the discrete empirical interpolation method (DEIM) is applied to solve a non-linear magnetostatic problem coupled with the circuit equations. To evaluate the reduction technique, the transient state of a three-phase transformer at no load is studied using the full finite-element model and the PGD–DEIM model. [ABSTRACT FROM AUTHOR]

As a portable high-performance computing technology for electromagnetic wave simulations, several kinds of dedicated computers for the finite-difference time-domain (FDTD) method have been considered. We previously proposed a dataflow architecture FDTD dedicated computer and showed that the estimated performance of the FDTD dataflow machine could exceed those of the high-end PC and GPU computers. On the other hand, the digital circuit of our previously proposed FDTD dataflow machine was inefficiently implemented in the field-programmable gate array (FPGA) owing to dual-mode operations of the normal grids and the perfectly matched layer (PML) grids, that is, almost half parts of the FPGA hardware resources were not used in our previously proposed machine. This paper proposes a modified architecture of the 3-D FDTD dedicated computer to improve the inefficient use of the FPGA hardware resources. The modified digital circuit of the FDTD scheme is designed to execute the FDTD calculation for eight normal grids or four PML grids. In the modified machine, there are almost no unused parts of hardware resources, and double size of FDTD scheme circuits can be implemented in the same size FPGA compared with the previously proposed machine. [ABSTRACT FROM AUTHOR]

This paper presents the generation of equivalent circuits from a finite-element (FE) model of electromagnetic devices using proper orthogonal decomposition (POD). This method effectively computes the frequency response of the reduced FE model constructed by the POD-based model order reduction. Then, the circuit parameters are determined so as to minimize the error between the frequency responses of the reduced FE model and equivalent circuit. The frequency characteristics of an inductor and the induction heating machine evaluated by the equivalent circuit are shown to be in good agreement with those computed from the original FE model. [ABSTRACT FROM AUTHOR]

This paper proposes an equivalent-circuit generation from the finite-element (FE) model of electromagnetic devices using a model order reduction (MOR). In this method, an equivalent circuit is directly generated from the reduced transfer function obtained using MOR based on Padé approximation via the Lanczos process. It is shown that the generated circuit yields sufficiently accurate results in both frequency and time domains. Moreover, the computational time of the present method is much shorter than that of the circuit generation based on frequency sweep using the conventional FE analysis. [ABSTRACT FROM AUTHOR]

Superparamagnetic tunnel junctions (SMTJs) are noise powered stochastic oscillators, which can harness thermal energy through phenomena such as stochastic resonance and noise-induced synchronization. This enables them to operate with the minimal externally supplied energy, and therefore, makes them promising candidates for implementing bioinspired computing schemes. These applications require understanding how SMTJs can be integrated into CMOS circuits. In this paper, we present a compact model of SMTJ, written in the VerilogA language, that can be used within standard integrated circuit design tools. This compact model is based on the Néel–Brown model and allows for fast simulations. We show that this model can reproduce the experimental characterization of a sample subjected to different values of dc currents. Then, we definitively demonstrate the validity of the model by confronting it to the experimental results in the case of a complex phenomenon: noise-induced synchronization. [ABSTRACT FROM AUTHOR]

This paper deals with the analysis of a 1-D magneto-dynamic model (MDM) of soft magnetic steel sheets (SMSSs) under arbitrary excitation conditions. In the presented analysis, the MDM is coupled with the static hysteresis model proposed by Tellinen. The coupled model of SMSSs is evaluated using measured excitation voltages as well as measured excitation currents directly as the model input variables, where both excitation cases are compared and evaluated versus measurements. The calculated results show a good agreement with the measurements. Based on the presented analysis properties, advantages, and flexibility of the MDM model as well as the limitations of the presented coupled model are pointed out, where guidelines for an improved coupling are also given. [ABSTRACT FROM AUTHOR]