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Electromagnetic Transient (EMT) simulation tools are typically developed using conventional procedural programming languages. On the other hand, modern high-level and equation-based programming languages, such as Modelica, are currently available. Modelica allows formulating models that are easy to develop, maintain and understand by expressing what needs to be computed without stating how it should be computed. This paper presents a Modelica-based simulator for electromagnetic transients. It is demonstrated that this approach offers significant advantages for developing sophisticated models. Computational performance and accuracy are compared to a conventional EMT-type simulation tool. [ABSTRACT FROM AUTHOR]

This paper illustrates the usefulness of the physics-based compact device models in investigating the impact of device behavioral nuances on the operation and performance of the circuits and systems. The industry standard MIT virtual source gallium nitride high electron-mobility transistor (GaN HEMT) (MVSG) model is used as the modeling framework to understand the operation of the GaN HEMTs and study the key device–circuit interactions in the GaN-based high-frequency and power conversion circuits. Details of the core model equations along with their physical underpinnings are presented along with the benchmark tests to verify the model’s convergence robustness and simulation accuracy. The usefulness of such a compact model in circuit design is highlighted through examples of the GaN-based high-voltage converter and RF-power amplifiers. It is shown that the slew-rates in hard-switched buck converters are determined by the dynamic charge distribution among the field plates in GaN HEMTs, indicating the importance of the device-level effect on circuit performance. Likewise, it is shown using the MVSG model that the performance metrics, such as drain efficiency and linearity, of the GaN RF-power amplifiers are heavily dependent on the device-level effects, such as access-region depletion, thermal effects, and charge-trapping effects. These GaN-based circuits designed using the MVSG model can be used as the example cases to demonstrate the importance of the accurate physical compact models in designing high performance circuits and systems in emerging technologies. [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]

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]

We present a physics-based compact model that captures the behavior of phase-transition materials. The model includes a self-heating module that captures the change in temperature with device operation and the resulting phase change. This is the first compact model that captures the temperature-dependent multidomain switching and the hysteresis behavior seen in such devices. The model is implemented in Verilog-A and validated with experimental data for various geometries and temperatures. It is further coupled with industry standard BSIM-BULK, ASM-HEMT, and BSIM-CMG models for SPICE simulation and validated for various phase-transition FETs, illustrating the previously proposed steep switching effect and a subthreshold slope below the Boltzmann limit of 60 mV/decade. [ABSTRACT FROM AUTHOR]

With the continuous drive toward integrated circuits scaling, efficient performance modeling is becoming more crucial yet more challenging. In this paper, we propose a novel method of hierarchical performance modeling based on Bayesian co-learning. We exploit the hierarchical structure of a circuit to establish a Bayesian framework where unlabeled data samples are generated to improve modeling accuracy without running additional simulation. Consequently, our proposed method only requires a small number of labeled samples, along with a large number of unlabeled samples obtained at almost no-cost, to accurately learn a performance model. Our numerical experiments demonstrate that the proposed approach achieves up to ${3.6 \times }$ runtime speed-up over the state-of-the-art modeling technique without surrendering any accuracy. [ABSTRACT FROM AUTHOR]

This paper presents a passive lumped model for DC cables and overhead lines, taking into account the frequency dependency of the per-unit-length parameters due to the skin and proximity effects. In comparison to distributed parameter line models, such as the Frequency-Dependent Phase model of PSCAD, the proposed model does not require line propagation delay extraction and does not impose any restrictions on the simulation timestep. As a result, for electrically short lines, the introduced model is more computationally efficient than distributed parameter models as it enables simulation using larger timesteps. The performance of the proposed model is evaluated in comparison with the PI model and the Frequency-Dependent Phase model through time-domain simulations of a DC microgrid and a radial DC distribution feeder. The studies performed in PSCAD focus on fault-induced transients. The results indicate that for electrically short lines the developed model is significantly more accurate compared to the PI model and provides similar accuracy with more computational efficiency compared to the Frequency-Dependent Phase model. [ABSTRACT FROM AUTHOR]

In this paper, a compact SPICE model of flexible transition metal dichalcogenide field-effect transistors (TMDFETs) is developed with considering effects when scaling the transistor size down to the 10-nm technology node. The model supports different transistor design parameters such as width, length, oxide thickness, and various channel materials, as well as the applied strain, which enables the evaluation of transistor- and circuit-level behavior under process variation and different levels of bending. Extensive device-level simulations are performed using this model, and TMDFETs are compared with different Si- and graphene-based devices. We performed circuit-level simulations, and reported the delay, power, and EDP of the benchmark circuits. Effects from process variation are also evaluated. These cross-technology studies show that TMDFET’s power is comparable to the low-power multigate devices (about 0.4% lower). The delay and EDP are 60% and 2.3% higher than the graphene-based devices, respectively. The developed compact model would enable SPICE-level circuit simulation for early assessment, design, and evaluation of futuristic TMDFET-based flexible circuits targeting advanced technology nodes. [ABSTRACT FROM AUTHOR]

Modular multilevel converters have become the technology of choice in high voltage direct current systems. They are composed of a large number of submodules, which poses significant computational challenges to electromagnetic transient simulations. To address this issue, scholars proposed several approaches that are a trade-off between simulation accuracy and computational burden, which mainly achieve numerical efficiency by adopting reduced and simplified models of the converter arm submodules. This paper proposes a different simulation paradigm based on sub-circuit isomorphism. It is suited for the analysis of intrinsically modular electronic circuits, as it exploits the common behavior of structurally identical submodules by clustering them together. This method does not require any simplification of the submodule electrical model and minimizes the number of equations to be solved at each time step of the time domain analysis, thereby significantly reducing the computational effort. Thus, this method is suitable for thorough simulations of ac/dc networks, which may require the implementation of detailed transistor-level representations of the converter submodules. [ABSTRACT FROM AUTHOR]

Leakage power is becoming significant in new generation IC chips. As leakage power is nonlinearly related to temperature, it is challenging to manage the thermal behavior of today’s multicore systems, since thermal management becomes a nonlinear control problem. In this paper, a new predictive dynamic thermal management (DTM) method with neural network thermal model is proposed to naturally consider the inherent nonlinearity between leakage and temperature. We start with analyzing the problems of using recurrent neural network (RNN) to build the nonlinear thermal model, and point out that there is exploding gradient induced long-term dependencies problem, leading to large model prediction errors. Based on this analysis, we further propose to use echo state network (ESN), which is a special type of RNN, as the leakage-aware nonlinear thermal model. We theoretically and experimentally show that ESN achieves much higher accuracy by completely avoiding the long-term dependencies problem. On top of this nonlinear ESN thermal model, we propose a novel model predictive control (MPC) scheme called ESN MPC, which uses iterative steps to find the optimal future power recommendations for thermal management. Being able to consider the leakage-temperature nonlinear effects and equipped with advanced control technique, the new method achieves an overall high quality temperature management with smooth and accurate temperature tracking. The experimental results show the new method outperforms the state-of-the-art leakage-aware multicore DTM method in both temperature management quality and computing overhead. [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 launching process of multistage synchronous induction coilgun (MSSICG) is a complex process involving multifield coupling, so it is time-consuming to iteratively optimize its structural parameters by stochastic optimization algorithm. A nonlinear regression modeling method of MSSICG based on mainstream machine learning methods is proposed in this paper. Rooted in the current filament model (CFM) verified by prototype experiment, the sample set for training and testing could be obtained by a hybrid experimental design method. The least-squares support vector machine (LSSVM), the kernel extreme learning machine (KELM), and the eco state network (ESN) were employed to learn the training samples. In order to improve the accuracy of the prediction model, the chicken swarm optimization (CSO) was introduced to pretrain the hyperparameters of the LSSVM and the KELM as well as the parameters of the dynamic reservoir of the ESN. The results show that the predictive modeling of MSSICG based on CSO-KELM has better accuracy and generalization performance. Based on the obtained regression model, the CSO algorithm was used to optimize the structural parameters of a five-stage coilgun. It turns out that the optimization based on nonparametric model has higher computational efficiency than the optimization method which requires large-scale iterative calculation. This provides a novel idea for the engineering design of the MSSICG. [ABSTRACT FROM AUTHOR]

Studying the propagation of harmonics in power grids represents a very important task nowadays. However, this demands for nonlinear models of power system devices representing a critical tradeoff between the accuracy and the computational cost. Simplified Volterra models with quasi-sinusoidal excitation have been recently proposed and they appear to be particularly suitable for the purpose. In this paper, these models have been applied to predict, for a given input voltage, the current harmonics of a full-bridge rectifier feeding an ohmic-capacitive load. Accuracy has been evaluated by means of both numerical simulations and experiments. Robustness has also been assessed by considering a set of realistic voltage waveforms different from those employed for the identification. Results highlight the remarkable accuracy of the proposed models in spite of the relatively small set of coefficients to be identified. This feature is extremely important when models have to be employed in frequency-domain simulations of large networks. [ABSTRACT FROM AUTHOR]

This paper presents a three-dimensional electrothermal numerical model of the medium voltage outdoor circuit breaker. The model was validated by heat run test performed under the conditions required by IEC 62271-1 and IEC 62271-100 standards, as well as some other specific requirements related to the breaker overload under low ambient temperature conditions and natural cooling. The purpose of this study was to build a numerical model of the medium-voltage circuit breaker that could be successfully applied for the redesign of the breaker for more demanding operating conditions with minimum physical test iterations. The numerical results obtained were found to be in a good agreement with experimental values having the average discrepancy of 3 K with the maximum below 5 K on busbars. [ABSTRACT FROM AUTHOR]

Considering the demand of III–V multigate (MUG) transistors for next-generation CMOS technologies, a compact model is required to test their performance in different circuits. The low effective mass and highly confined geometry of these MUG devices demand the use of computationally expensive coupled Poisson–Schrödinger (PS) solver for terminal charges and surface potential. In this paper, we propose an approximation, which decouples the PS equations and enables the development of a computationally efficient analytical model. The surface potential and semiconductor charge equations for III–V low effective mass channel cylindrical nanowire (NW) transistors are derived using the proposed approximation. The proposed model is physics-based and does not include any empirical parameters. The accuracy of the model is verified across NWs of different sizes and materials using the data from the 2-D PS solver and found to be accurate. [ABSTRACT FROM AUTHOR]

Many advanced energy conversion systems utilize multiphase (e.g., six or more phases) electrical machines that feed high-count-pulse (e.g., 12 or more pulses) rectifiers for supplying dc power. Efficient simulation of such power systems in commonly-used state-variable-based programs requires fast and accurate models of electrical machines and power electronic converters with compatible interfaces. As an alternative to the existing $qd$ and voltage-behind-reactance (VBR) machine models, this paper develops a constant-parameter VBR model for six-phase permanent magnet synchronous machines to offer computationally efficient interface. For system-level studies where the switching details of rectifiers can be neglected, a multiple-reference-frame parametric-average-value model is developed for the 12-pulse rectifiers that provides fast simulation and preserves the dominant ac harmonics of interest. The accuracy and numerical efficiency of the proposed machine-converter models are verified using the detailed and alternative existing models. [ABSTRACT FROM AUTHOR]

Defects or traps in semiconductors and nano devices that randomly capture and emit charge carriers result in low-frequency noise, such as burst and $1/f$ noise, which are important concerns in the design of both analog and digital circuits. The capture and emission rates of these traps are functions of the time-varying voltages across the device, resulting in nonstationary noise characteristics. Modeling of low-frequency, nonstationary noise in circuit simulators is a long-standing open problem. It has been realized that the low-frequency noise models in circuit simulators were the culprits that produced erroneous noise performance results for circuits under strongly time-varying bias conditions. In this paper, we present two fully nonstationary models for traps, a fine-grained Markov chain model and a coarse-grained Langevin model based on similar models for ion channels in neurons. The nonstationary trap models we present subsume and unify all of the work that has been done recently in the device modeling and circuit design literature on modeling nonstationary trap noise. We provide a detailed explication of these models with regard to their stochastic properties and develop carefully crafted circuit simulation techniques that are stochastically correct. We have implemented the proposed techniques in a MATLAB-based circuit simulator, by expanding the industry standard compact MOSFET model PSP to include a nonstationary description of oxide traps. We present results obtained by this extended model and the proposed simulation techniques for the low-frequency noise characterization of a common source amplifier and the phase jitter of a ring oscillator. [ABSTRACT FROM PUBLISHER]

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]

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]

Analog components are fundamental blocks of smart systems, as they allow a tight interaction with the environment, in terms of both sensing/actuation and communication. This impacts on the design of the overall system, and mainly on the validation phase, that thus requires the joint simulation of digital and analog aspects. In this scenario, this paper proposes the automatic conversion of analog models to C++-based languages, to remove the overhead of co-simulation with traditional virtual platform tools. The proposed methodology allows to convert a given analog description to either: 1) a fully equivalent description or 2) an abstract representation for faster simulation which models only the aspects of interest. Effectiveness and correctness have been proved on a number of case studies that highlight the effectiveness and potentiality of the proposed methodology. [ABSTRACT FROM AUTHOR]

The Partial Element Equivalent Circuit (PEEC) method is promising numerical technique for three-dimension electromagnetic modeling across various application fields. In the framework of the PEEC method, the partial elements modeling the magnetic and electric field coupling between elementary volumes and surfaces are computed by double-folded volume and surface integrals. Assuming the quasi-static hypothesis and an orthogonal mesh, the integrals have been computed by the analytical formulas derived in literature, which significantly reduces the computational time in comparison to the numerical integration. However, the existing analytical formulas are affected by significant numerical errors for certain PEEC structural mesh necessary to model the skin and proximity effects with a higher accuracy. To utilize the full potential of the PEEC method, the calculation of partial elements has to be carefully addressed, which has not been investigated in a comprehensive way so far. Accordingly, this paper presents a systematic accuracy analysis of the existing closed-form analytical formulas and methods for calculating the self and mutual inductances between two rectangular conductors. Additionally, a new strategy to select a proper analytical formula depending on the dimensions and positions of two conductors is proposed, which allows the mutual inductance extraction with a relative error of less than 0.1 $\%$. The new method is systematically validated on examples of 3-D dense PEEC systems using the quadruple precision arithmetic as reference. [ABSTRACT FROM AUTHOR]

Fast front pulses from lightning and switching conditions produce transient overvoltages and dielectric stresses that can result in premature deterioration or failure of transformer windings. Predicting these conditions in new transformer designs requires the implementation of internal winding models. This paper analyzes the accuracy and performance of different transformer winding models available in the literature, by means of comparisons with time- and frequency-domain measurements on a 2000-turns disk-type winding prototype, as well as evaluation of the computer time needed by each model to perform the corresponding simulation of the same prototype. The results show that including the frequency dependence of the model parameters is a decisive factor to accurately reproduce the measurements. They also show that a lumped parameter model described in a turn-by-turn basis can provide accurate results and requires shorter simulation time than a distributed parameter model. [ABSTRACT FROM AUTHOR]

This paper proposes an improved hybrid method to compute the parameters of the two-diode model of photovoltaic (PV) module. Unlike previous methods, it attains the speed of the analytical approach by utilizing only datasheet information. Furthermore, its accuracy is not compromised as it does not require simplifications in its computation. Four parameters are determined analytically, while the remaining three are optimized by using an evolutionary algorithm, i.e., the differential evolution. The speed is improved because the parameters are optimized only once, i.e., at standard test condition, while the values at other conditions are computed analytically. Furthermore, a procedure to guide the initial conditions of the Newton–Raphson iteration is introduced. For validation, the algorithm is compared to other established computational methods for mono-, polycrystalline, and thin film modules. When evaluated against the experimental data, the mean absolute error is improved by one order of magnitude, while the speed is increased by approximately threefold. The standard deviation of the decision parameters over 100 independent runs is less than 0.1—which suggests that the optimization process is very consistent. Due to its speed and accuracy, the method is envisaged to be useful as a computational engine in PV simulator. [ABSTRACT FROM PUBLISHER]

The emerging voltage source converters (VSCs) such as hybrid cascaded multilevel converters (HCMCs) are promising converter technologies which enable higher converter efficiency, compactness, and DC fault resilience for high voltage direct current (HVDC) transmission. However, the large number of switching events due to the converters’ submodules introduces a heavy computational burden for electromagnetic transient (EMT) simulations. Efficient and accurate EMT-type converter models play a vital role in the control and design of HVDC converters. Several computationally efficient models for the HCMCs are proposed in this paper, including the detailed equivalent model (DEM) and several average value models (AVMs) of varying accuracy. Additionally, a combined model is proposed which allows the users to switch among the DEM and AVMs during dynamic simulations. The proposed models are validated against the DEM for dynamic transients. The simulation results demonstrate good modeling accuracy of the proposed models. The AVMs are also shown to significantly improve simulation efficiency compared to the DEM, which is very desirable especially for HCMCs with a large number of submodules. [ABSTRACT FROM AUTHOR]

Many critical electronic design automation (EDA) problems suffer from the curse of dimensionality, i.e., the very fast-scaling computational burden produced by large number of parameters and/or unknown variables. This phenomenon may be caused by multiple spatial or temporal factors (e.g., 3-D field solvers discretizations and multirate circuit simulation), nonlinearity of devices and circuits, large number of design or optimization parameters (e.g., full-chip routing/placement and circuit sizing), or extensive process variations (e.g., variability /reliability analysis and design for manufacturability). The computational challenges generated by such high-dimensional problems are generally hard to handle efficiently with traditional EDA core algorithms that are based on matrix and vector computation. This paper presents “tensor computation” as an alternative general framework for the development of efficient EDA algorithms and tools. A tensor is a high-dimensional generalization of a matrix and a vector, and is a natural choice for both storing and solving efficiently high-dimensional EDA problems. This paper gives a basic tutorial on tensors, demonstrates some recent examples of EDA applications (e.g., nonlinear circuit modeling and high-dimensional uncertainty quantification), and suggests further open EDA problems where the use of tensor computation could be of advantage. [ABSTRACT FROM PUBLISHER]

This paper proposes a new method of decoupling and subdividing electrical circuits, containing power-electronics devices, in order to achieve fast and accurate real-time simulation. In this technique, each state variable can be discretized using different discretization methods. Combining implicit and explicit ODE solvers, state-space equations are decoupled while remaining accurate and stable. Unlike most traditional decoupling techniques previously proposed, the proposed one does not require artificial delay or supplementary states to be added in order to decouple the system. Furthermore, this technique is meant to be implemented with commercially available simulation software. By doing so, a large and complex circuit containing several hundreds of state variables can be easily and accurately simulated with minor modification to the existing models. Finally, stability and accuracy of the proposed technique are thoroughly demonstrated in a numerical example during steady state and under faulty conditions. [ABSTRACT FROM PUBLISHER]

Electromagnetic transient-type (EMT-type) programs solve nodal analysis or modified-augmented-nodal-analysis (MANA) formulation-based power system network equations (PSNE). The PSNE coefficient matrix can be either constant or time varying depending on the utilized synchronous machine (SM) model. Therefore, a computational efficiency comparison for the SM models requires accounting for the refactorization scheme and the utilized sparse matrix solver (SMS). In addition, MANA formulation does not require or force admittance model usage and enables flexibility while representing the SMs in PSNE. This paper compares computational performances of various SM models for a practical case and accounts for the refactorization scheme, the utilized SMS, and the SM representation in MANA formulation. [ABSTRACT FROM PUBLISHER]

Model order reduction (MOR) techniques play a crucial role in the computer-aided design of modern integrated circuits, where they are used to reduce the size of parasitic networks. Unfortunately, the efficient reduction of passive networks with many ports is still an open problem. Existing techniques do not scale well with the number of ports, and lead to dense reduced models that burden subsequent simulations. In this paper, we propose TurboMOR-RC, a novel MOR technique for the efficient reduction of passive RC networks. TurboMOR-RC is based on moment-matching at dc, achieved through efficient congruence transformations based on Householder reflections. A novel feature of TurboMOR-RC is the block-diagonal structure of the reduced models, that makes them more efficient than the dense models produced by existing techniques. Moreover, the model structure allows for an insightful interpretation of the reduction process in terms of system theory. Numerical results show that TurboMOR-RC scales more favorably than existing techniques in terms of reduction time, simulation time, and memory consumption. [ABSTRACT FROM AUTHOR]

Recent focus on component-network interfacing has greatly increased the maximum step size at which machine models can be simulated accurately and stably in nodal-analysis-based electromagnetic transients programs (EMTP-type). However, considerably smaller step sizes are often used in practice due to the presence of fast modes in external power networks. To further improve simulation speed, this paper proposes a multirate framework for EMTP-type machine models connected to dynamically faster power systems. In particular, two multirate induction machine models based on the voltage-behind-reactance (VBR) formulation are presented. These new models can be interfaced directly with commercial EMTP-type programs with no modifications to their computational engines. The presented computer studies demonstrate the superior combination of numerical accuracy and efficiency of the proposed multirate models compared with the existing models. [ABSTRACT FROM PUBLISHER]

Five-phase electric machines possess several distinct features and are sometimes considered in vehicular power systems and various special-purpose energy sources. Design and analysis of such machine-converter systems are highly dependent on simulation software programs, where accurate and numerically efficient dynamic models of five-phase synchronous machines are essential. Depending on levels of fidelity and interfacing compatibility, the traditional models for five-phase machines include the coupled-circuit-phase-domain (CCPD) and qd0 models. To achieve a computationally-efficient model suitable for many simulation programs, in this paper, a new constant-parameter voltage-behind-reactance (CPVBR) model is proposed for five-phase synchronous machines where a simple interfacing circuit is achieved with constant RL branches. The proposed model is validated by experimental measurements and simulation studies. The proposed CPVBR model is demonstrated to have superior numerical efficiency and simulation speed compared to the existing conventional models. [ABSTRACT FROM AUTHOR]

Designing of power electronics converters seldom considers multiscale coupling relationship between components and circuits. Although macroscale is computationally efficient, it barely contains the micro implications about aging, deterioration, transient performance, etc. Conversely, the microscale obtains multiple observation scope, however, with computational disaster. In this paper, the multiscale method is applied in the power electronic modeling which provides a qualitative methodology to combine the scales appropriately, and to obtain the dynamic response under the action of multiphysics accurately. Firstly, the concept of multiscale and the scale division of power electronic system are expounded. Considered the dynamic behavior of components and converters with different complexity, the framework of multiscale converters and modeling method is proposed. Afterwards, a scalable coupling separation method is presented, providing interfaces for the multiphysics and dielectric physics. Additionally, a multiscale conversion algorithm considering both efficiency and accuracy is designed. In the end, a DC/DC converter is taken for the verification. The feasibility and advantages of multiscale method and conversion algorithm have been demonstrated in accuracy, consistency and multiple analysis. By filling in the microscale observation, it is plausible to provide theoretical guidance for reducing margin, accurate analysis and reliability estimation of electronic components. [ABSTRACT FROM AUTHOR]

The device-level real-time simulation of power converters is constrained by the contradiction between the required short simulation time step to describe the transient behaviors and the large computational amount caused by the nonlinearities of switches’ models. In this paper, a novel low-latency device-level power converter modeling approach is proposed for field programmable gate array (FPGA)-based real-time simulation. A piecewise linear insulated-gate bipolar transistor (IGBT)/diode transient model is proposed based on the inductive switching behaviors. The switching transient is modeled into four phases, which are identified by the boundaries between three operating regions of IGBT and between two operating modes of a diode. Moreover, each phase is approximated by a linear continuous behavior in order to reduce the real-time computational amounts. Accompanied by the effective boundary identification, the device-level IGBT/diode model can be efficiently integrated into the real-time simulation with low computational latency. A dc–dc–ac topology model is implemented on the FPGA-based real-time platform, as a case study to verify the effectiveness and practicability of the proposed approach. With the help of circuit partitioning techniques, the device-level converter model can be simulated with a 50-ns time step on FPGA. Moreover, the accuracy of FPGA-based simulation results is validated by the error evaluation with respect to the results from offline simulation tools. [ABSTRACT FROM AUTHOR]

Six-phase electrical machines are often found in special purpose applications, such as vehicular, ship, and aircraft power systems, and are now becoming considered in renewable energy generation. For design and analysis of such power systems, accurate and numerically efficient models are required for various transient simulation programs. Recently, a constant-parameter voltage-behind-reactance (CPVBR) model has been developed for magnetically linear six-phase synchronous machines as an alternative to the conventional qd0 and VBR machine models. In this paper, a saturable CPVBR model is presented for six-phase machines, which includes the main flux saturation and achieves magnetically decoupled and constant RL interfacing branches. The new magnetically decoupled CPVBR (DCPVBR) model has many advantages for implementation in commonly available simulation programs where it can be easily interfaced with inductive and/or power-electronic circuit elements. The proposed DCPVBR model is demonstrated to have improved computational performance compared to the conventional qd0 and VBR models. [ABSTRACT FROM AUTHOR]

This paper presents a coupled electromagnetic and thermal design methodology which addresses the problem of balancing accuracy against computation time. A case study on a short-duty permanent-magnet (PM) linear actuator is used to illustrate the approach. The proposed method employs a two-dimensional electromagnetic finite-element (FE) model coupled with a detailed thermal equivalent circuit (TEC) model which is automatically constructed and parameterized using geometric and material data. A numerical method of estimating the equivalent thermal properties of the winding amalgam is used along with published empirically derived convection and radiation heat transfer correlations. The relatively high number of network nodes and more accurate thermal material properties minimizes model calibration and allows improved temperature prediction, including winding hot spots, while maintaining a low computational cost for both steady-state and transient analyses. A comparison between experimental and theoretical actuator performance shows that the design methodology provides good accuracy electromagnetic and transient thermal performance predictions without the need for direct model calibration and can yield an optimized design within an acceptable time frame. [ABSTRACT FROM PUBLISHER]

Yield optimization is a challenging topic in electronic circuit design. Methods for yield optimization based on Monte Carlo (MC) analysis of a circuit whose behavior is reproduced by simulations usually require too many time expensive simulations to be effective for iterative optimization. In this paper, we propose a method which tackles the yield optimization problem by combining a support vector machine (SVM) surrogate model (SM) of the circuit to perform the MC analysis and evaluate the yield, and an efficient optimization method to maximize the yield evaluated using the SVM SM. We report the numerical results obtained for the design of two real consumer circuits provided by STMicroelectronics, and we compare these results with the ones obtained using the industrial benchmark currently adopted at STMicroelectronics for yield optimization. These preliminary results show that the method is promising to be very efficient and capable of reaching design solutions with high values of the yield. [ABSTRACT FROM PUBLISHER]

This paper proposes a numerical solution of the nonlinear equations that describes the hysteretic behavior of ferromagnetic materials. From the proper definition and solution of these equations, an equivalent circuit model for a ferromagnetic core is developed and proposed. The results obtained from the equivalent circuit are compared with those obtained by a rigorous numerical solution. [ABSTRACT FROM AUTHOR]

Memristors are promising nanoelectronic devices for the implementation of future AI-driven sensor-processor electronic systems, which are essential for the ongoing digitalization of our world. Accurate and computationally cost-effective models for the manufactured memristors are essential for the design of such systems, especially for the simulation of large circuits. In this brief we address the simplification of the JART memristor model, a generic physics-based model of Valence Change Mechanism (VCM) memristors which accurately describes the dynamic behavior of fabricated memristor devices. Furthermore, the proposed model and simplification methodology have the potential to capture the dynamics of a wide range of memristor devices. Importantly, the implicit description of the current through the memristor is replaced by an explicit mathematical relationship. The proper reproduction of memristor dynamics, verified by applying the system-theoretic Dynamic Route Map (DRM) graphical analysis tool, applicable to first-order systems, can be observed through the proposed simplified model and enables the time-efficient simulation of large arrays of VCM devices. [ABSTRACT FROM AUTHOR]

The computational cost for the simulation of detailed models of machine-rectifier systems is expensive because of repetitive diodes switching. Average-value models (AVMs) of machine-rectifier systems have been developed that can alleviate the computational burden by neglecting the details of the switching of each individual diode while retaining the average characteristics. This paper proposes an alternative formulation of numerical AVMs of machine-rectifier systems, which makes direct use of the natural dynamic impedance of the rectifier without introducing low-frequency approximations or algebraic loops. By using this formulation, direct interface of the AVM is achieved with inductive circuitry on both the ac and dc sides allowing traditional voltage-in, current-out formulations of the circuitry on these sides to be used with the proposed formulation directly. This numerical AVM formulation is validated against an experimentally validated detailed model and compared with previous AVM formulations. It is demonstrated that the proposed AVM formulation accurately predicts the system's low-frequency behavior during both steady and transient states, including the cases where previous AVM formulations cannot predict accurate results. Both run times and numbers of time steps needed by the proposed AVM formulation are comparable to those of existing AVM formulations and significantly decreased compared with the detailed model. [ABSTRACT FROM AUTHOR]

Modeling partially shaded photovoltaic (PV) systems for online applications such as model-based MPPTs requires a PV circuit model with low computational time to simulate the large number of connected PV units within a reasonable amount of time. Unfortunately, the accurate PV models available in the literature are complex and suffer from high computational time due to their dependence on a transcendental implicit equation. This paper proposes a photovoltaic circuit model featuring lower computational time and comparable accuracy. The model utilizes the accuracy of the practical PV model and reduces the computational time by replacing the model series resistance with a third-degree-polynomial voltage-dependent source. The proposed model mimics the accurate characteristics of the practical model without being dependent on a transcendental implicit equation, thus providing low computational time. The model also introduces a new parameter to enhance the model's accuracy at low irradiance. The effectiveness of the model is shown by comparing the computational time and accuracy of the proposed model with those of the available models. A case study of partially shaded PV systems shows that the percentage of reduction in computational time improves with increases in the number of PV units in a simulated PV system, providing a clear advantage when simulating large PV systems. [ABSTRACT FROM PUBLISHER]

Computational intelligence techniques are used to approximate the nonlinear operation of \LiFePO4 batteries using rule-based systems. In this paper, rule-based systems are not directly fitted to data, but comprise constructive blocks in a differential-equation-based dynamical model that is numerically integrated to infer battery voltage, charge, and temperature. The design methodology has been validated with three different \ \hspace*-1.8ptLiFePO4 batteries, and the results were found to be more accurate than those of a selection of statistical models and state-of-the-art artificial intelligence techniques. [ABSTRACT FROM PUBLISHER]

This paper describes a novel approach for passivity enforcement of compact dynamical models of electrical interconnects. The proposed approach is based on a parameterization of general state-space scattering models with fixed poles. We formulate the passivity constraints as a unitary boundedness condition on the \(\mathcal {H}_\infty \) norm of the system transfer function. When this condition is not verified, we use it as an explicit constraint within an iterative perturbation loop of the system state-space matrices. Since the resulting optimization framework is convex but nonsmooth, we solve it via localization based algorithms, such as the ellipsoid and the cutting plane methods. The proposed technique solves two critical bottleneck issues of the existing approaches for passivity enforcement of linear macromodels. Compared to quasi-optimal schemes based on singular value or Hamiltonian eigenvalue perturbation, we are able to guarantee convergence to the optimal solution. Compared to convex formulations based on direct Bounded Real Lemma constraints, we are able to reduce both memory and time requirements by orders of magnitude. We demonstrate the effectiveness of our approach on a number of cases for which existing algorithms either fail or exhibit very slow convergence. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to present a further approach for analyzing the air electric arc in low-voltage circuit breakers (LVCBs). In order to achieve that, a new simulation model and experimental tests have been carried out. The simulation model has been designed using ANSYS CFX, a finite-volume method commercial software. This model has been defined as a 3-D geometry, with a high density structured hexahedral mesh, P1 radiation model and hot air characteristics for thermal plasma properties and transport coefficients. The model is applied to simulate the behavior of an LVCB for 50, 100, and 200 A with different numbers of splitter plates in the arc chamber and different locations for the arc ignition. As result, arc elongation and arc voltage increase have been observed when increasing the splitter plates number. Also faster arcs for higher ignition zones and greater expansion and diffusion for higher input currents have been obtained. These simulation results have been verified and validated. The verification process has been accomplished calculating the numerical errors, by means of the grid convergence index and Courant-Friedrichs–Lewis number. Thus, the most accurate mesh densities, time steps, and radiation models have been selected. Finally, the validation process has been achieved performing real experimental tests in the laboratory, proving that the results of the simulation model are close to real scenarios. [ABSTRACT FROM PUBLISHER]

In electromagnetic transient (EMT) simulation, 80–97% of the computational time is devoted to solving the network equations. A key observation is that the sub-matrix representing the interaction between two far-away groups of buses is usually sparse and can be approximated by a low-rank matrix. Based on this observation, we propose a novel low-rank approximation method which permits ${O(N \log N)}$ -time matrix-vector multiplication for each network solution time step. Comprehensive numerical studies are conducted on a 39-bus system and a 179-bus system from the literature, and large cases created from the two systems. The results demonstrate that the proposed approach is up to $2.8\times$ faster than the state-of-the-art sparse LU factorization based network solution, without compromising simulation accuracy. Since our low-rank approximation is highly parallelizable, further speedup may be possible. [ABSTRACT FROM AUTHOR]

Interfacing of electrical machine models with ac power networks has a significant impact on numerical accuracy and efficiency in state-variable-based transient simulation programs. This paper continues the recent work in this area by proposing a new explicit constant-parameter voltage-behind-reactance (VBR) induction machine model that includes main flux saturation and allows a direct interface to any external network. The proposed model uses numerical approximations to achieve a decoupled interfacing circuit with constant RL branches that is easy to use in many simulation programs. Computer studies demonstrate that the proposed model provides high numerical accuracy for machines with a diverse range of parameters, even at fairly large integration step sizes. [ABSTRACT FROM AUTHOR]

We present a numerical modeling and simulation paradigm for multidomain, multiphysics systems with components modeled both in a lumped and distributed manner. The lumped components are modeled with a system of differential-algebraic equations (DAEs), whereas the possibly nonlinear distributed components that may belong to different physical domains are modeled using partial differential equations (PDEs) with associated boundary conditions. We address a comprehensive suite of problems for nonlinear coupled DAE–PDE systems including 1) transient simulation; 2) periodic steady-state (PSS) analysis formulated as a mixed boundary value problem that is solved with a hierarchical spectral collocation technique based on a joint Fourier–Chebyshev representation, for both forced and autonomous systems; 3) Floquet theory and analysis for coupled linear periodically time-varying DAE–PDE systems; 4) phase noise analysis for multidomain oscillators; and 5) efficient parameter sweeps for PSS and noise analyses based on first-order and pseudo-arclength continuation schemes. All of these techniques, implemented in a prototype simulator, are applied to a substantial case study: a multidomain feedback oscillator composed of distributed and lumped components in two physical domains, namely, a nano-mechanical beam resonator operating in the nonlinear regime, an electrical delay line, an electronic amplifier and a sensor-actuator for the transduction between the two physical domains. [ABSTRACT FROM AUTHOR]

Six-phase electrical machines have received significant attention in the literature due to their use in special purpose applications (e.g., aircraft, naval, and vehicular systems). Recently, such machines have also been considered for renewable energy systems including wind generators. Modeling of such machines in commonly available transient simulation programs is not straightforward, especially when the machine model is interfaced with external inductive network and/or power electronic converters. The available modeling approaches include the classical qd 0 model, the coupled-circuit-phase-domain and the voltage-behind-reactance (VBR) models (each having its interfacing challenges). This paper extends the prior research in this area and proposes a constant-parameter VBR model that has a very convenient constant RL−branch interfacing circuit (even for salient pole machines), which makes it simple to implement in most state-variable-based simulations programs. The presented computer studies demonstrate significant numerical advantages of the new model over the existing alternative models. [ABSTRACT FROM PUBLISHER]

A methodology to create and develop electrical compact models for memristive devices is presented. It comprises a six-step algorithm that uses experimental data of memristive devices in order to obtain a compact model suitable for circuit-level simulations. The model methodology makes use of the definition of the intrinsic variables of memristive systems, to obtain the state map that describes the system, from which the mathematical expressions of the model are obtained. In order to illustrate the usage of the algorithm, a compact memristive model is developed by using experimental data from a TiO2-based resistive switching (RS) device. The resulting mathematical model is compared to the experimental data by computing the mean absolute percentage error (MAPE) between both, which results in 11%, and reduces to 6% after a piecewise approach. The circuit-level representation is implemented using a SPICE macromodel and a Verilog-A module, from which the memristive behavior is also properly reproduced. [ABSTRACT FROM AUTHOR]

A new computationally efficient 2-D large-signal code TESLA-FW has been developed to model traveling wave tubes (TWTs) using folded (or serpentine) waveguide (FW) slow-wave structures. The code incorporates a recently published shunt-loaded transmission line model of the structure and takes advantage of a new time advance algorithm recently implemented in the code TESLA-CC. The new code has been applied to modeling $G$ -band (220 GHz) serpentine and FW TWTs. Results compare very favorably with those obtained from the 3-D particle-in-cell (PIC) code MAGIC3D and with experimental data. Typical running times of TESLA-FW are 1–2 orders of magnitude less than those of 3-D PIC codes. [ABSTRACT FROM AUTHOR]

An optimization of the current-to-voltage transfer characteristic of a graphene FET (GFET) compact model, based on drift-diffusion carrier transport, is presented. The improved accuracy at Dirac point extends the model usability for GFETs when scaling parameters, such as voltage supply, gate length, oxide thickness, and mobility, for circuit design exploration. The model’s accuracy is demonstrated through fitting to GFETs processed in-house. The model has been written in a standard behavioral language, and extensively run in an analog circuit simulator for designing basic circuits, such as inverters and cascode cells, demonstrating its robustness. [ABSTRACT FROM AUTHOR]