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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]

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]

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]

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]

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]

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]

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]

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]

A volume integral formulation using facet elements to compute eddy currents in thin conductive shells is presented. The formulation is general and considers the field variation through the depth due to the skin effect. The formulation leads to an equivalent lumped elements circuit that can be coupled with an external circuit. The resolution of the circuit is achieved by the independent loops method. The formulation has been validated because of two numerical examples. Results are compared with an axisymmetric finite-element method (FEM) and another shell formulation implemented in a 3-D FEM. [ABSTRACT FROM PUBLISHER]

After its recent improvements described here, open source finite element software Elmer is shown to be a highly efficient option for electrical machine modeling. The parallelization of computational burden is shown to be a necessity. The methods implemented enable applying fully parallel computation to electrical machine models, including rotation and electrical circuits. Computational experiments performed demonstrate that Elmer can effectively utilize several hundreds of computational cores in parallel, making it an attractive alternative when computational speed is of high importance. [ABSTRACT FROM PUBLISHER]

The proper orthogonal decomposition combined with the discrete empirical interpolation method is investigated in order to reduce a finite-element model of a multiple-input non-linear device. The non-linear reduced problem is solved using the Newton–Raphson method. The transient state of a three-phase transformer with a variable load is studied with the proposed reduction method for different supply voltage conditions. [ABSTRACT FROM PUBLISHER]

To eliminate the inefficiencies of the existing physics-based planar-gate insulated gate bipolar transistor (IGBT) model without considering an arbitrary free-carrier injection condition and 2-D effects at the MOS end of the drift region in the transient performance simulations, a coupled circuit-ambipolar diffusion equation model and its numerical solution methodology is proposed. Moreover, the proposed model treads the nonlinearity in a complete transient manner. The accuracy of the proposed model is validated by comparing the computed results with both experimental ones and those of an existing model. [ABSTRACT FROM AUTHOR]

A consistent and computationally efficient finite-element model for the simulation of the steady-state operation of surface-mounted permanent magnet brushless dc motors driven from quasi-square wave inverters is presented. The methodology combines the magnetostatic finite-element and the steady-state time-periodic circuit models with time averaging. A weak field-circuit coupling is established through the effective constant current and lumped parameters estimated at various loading conditions. The performance characteristics, determined via the proposed model for two different motors, are comparable with those obtained from the comprehensive time-stepping finite-element model, with the execution time being approximately a hundred times shorter for the former. [ABSTRACT FROM AUTHOR]

For the time domain simulation of coupled systems, co-simulation is a prominent approach. The contraction and the speed of convergence of corresponding schemes depend on the design of the coupling interface and the computational order among others. Here, the field/circuit coupling is investigated, where the standard approach of decoupling is to separate the field and the circuit part. In this context, we introduce a new decoupling approach: $LR$ -coupling. For this coupling type, general stability and contraction are directly influenced by the coupling interface. Thus, these properties are independent of embedded electric networks or embedded electromagnetic devices. Furthermore, first investigations demonstrate that the use of a dedicated coupling interface may enhance the convergence properties, i.e., it may reduce the computational effort for prescribed tolerances. [ABSTRACT FROM AUTHOR]