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1.
We consider model order reduction of integrated circuits with semiconductor devices. Such circuits are modeled using modified nodal analysis by differential‐algebraic equations coupled with the nonlinear drift‐diffusion equations. A spatial discretization of these equations with a mixed finite element method yields a high dimensional nonlinear system of differential‐algebraic equations. Balancing‐related model reduction is used to reduce the dimension of the decoupled linear network equations, whereas the semidiscretized semiconductor model is reduced using proper orthogonal decomposition. Because the computational complexity of the reduced‐order model through the nonlinearity of the drift‐diffusion equations still depends on the number of variables of the full model, we apply the discrete empirical interpolation method to further reduce the computational complexity. We provide numerical comparisons that demonstrate the performance of the presented model reduction approach. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

2.
The increasing operating frequencies and decreasing IC feature size call for 3‐D electromagnetic (EM) methods, such as the Partial Element Equivalent Circuit (PEEC) method, as necessary tools for the analysis and design of high‐speed systems. Very large systems of equations are often generated by 3‐D EM methods and model order reduction (MOR) techniques are commonly used to reduce such a high model complexity. A typical design process includes optimization and design space exploration, and hence requires multiple simulations for different design parameter values. Traditional MOR techniques perform model reduction only with respect to frequency and such design activities call for parameterized MOR (PMOR) methods that can reduce large systems of equations with respect to frequency and other design parameters of the circuit, such as geometrical layout or substrate characteristics. We present a novel PMOR technique applicable to the PEEC method that provides parametric reduced order models, stable and passive by construction, over a user defined design space. We treat the construction of parametric reduced order models on scattered design space grids. Pertinent numerical examples validate the proposed approach. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

3.
Large‐scale RCL circuits with a large number of ports have been widely employed to model interconnect circuits, such as the power/ground networks, clock distribution networks and large data buses in VLSI. The input‐dependent moment‐matching technique, which takes the input excitations into account when constructing the projection matrices for the reduced‐order systems, has been proposed to simulate this type of circuits. The existing input‐dependent moment‐matching methods suffer from either numerical instability in the case of extended Krylov subspace (EKS) and improved extended Krylov subspace (IEKS) methods, or unbearable memory consumption and CPU cost for the EXPanded LINearization (EXPLIN) method. In this paper, a Non‐Homogeneous ARnoldi (NHAR) process, which consists of a memory‐saving and computation‐efficient linearization scheme and a numerical stable partial orthogonalization Arnoldi method, is proposed for the generation of the orthonormal projection matrix. By applying the obtained projection matrix to generate the reduced‐order model, we derive the NHAR method for the model‐order reduction of large‐scale RCL circuits with a large number of ports. The proposed NHAR method can guarantee moment matching, numerical stability and passivity preserving. Compared with the EXPLIN method, NHAR can remarkably reduce the size of the linearized system and therefore can greatly save the memory consumption and computational cost with almost the same accuracy. Moreover, NHAR is numerically stable and can achieve higher accuracy with approximately the same computational cost compared with the EKS and IEKS methods. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

4.
This paper proposes a hybrid adaptive sampling algorithm to automate the generation of reduced order models for systems described by large‐scale frequency dependent state‐space models. The evaluation of the frequency dependent state‐space model for each frequency sample can be computationally expensive. The distribution of frequency samples must be optimized to avoid oversampling and undersampling. In order to have an optimum number of frequency samples, the proposed algorithm uses the reflective exploration technique for the adaptive selection of samples, and the sampling is further refined using a binary search to validate the frequency dependent reduced order models. Projection‐based model order reduction techniques are used for obtaining the reduced order model. The projection matrix for each frequency sample is merged to obtain a common projection matrix for all samples. However, in certain cases when the number of sample points increases, the merged projection matrix also increases in dimension and might fail to provide a satisfactory reduction in model size. Thus, the merged projection matrix is truncated based on its singular values to obtain a compact common projection matrix. Then, the reduced order state‐space matrices per frequency are interpolated over the frequency range of interest to obtain the system response. Pertinent examples validate the proposed hybrid adaptive sampling algorithm. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

5.
This work studies the identification of errors‐in‐variables (EIV) systems. An asymptotic method (ASYM) is developed for the EIV system. Firstly, an auto regressive with exogeneous (ARX) model estimation method is proposed, which is consistent for EIV systems. Then the asymptotic variance expression of the estimated high‐order ARX model is derived, which forms the basis of the ASYM method. In parameter estimation, the ASYM starts with a high‐order ARX model estimation followed by a frequency domain weighted model reduction. The obtained model is consistent, and its efficiency needs to be investigated. Besides parameter estimation, a criterion for model order selection is proposed, which is based on frequency domain considerations, and the frequency domain error bound is established that can be used for model validation. Simulations and comparisons with other methods are used to illustrate the performance of the method.  相似文献   

6.
This paper studies the problem of exponential H model reduction for continuous‐time switched delay system under average dwell time (ADT) switching signals. Time delay under consideration is interval time varying. Our attention is focused on the construction of the desired reduced order models, which guarantee that the resulting error systems under ADT switching signals are exponentially stable with an H norm bound. By introducing a block matrix and making use of the ADT approach, delay‐dependent sufficient conditions for the existence of reduced order models are derived and formulated in terms of strict linear matrix inequalities (LMIs). Owing to the absence of non‐convex constraints, it is tractable to construct an admissible reduced order model. The effectiveness of the proposed methods is illustrated via two numerical examples. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

7.
Electromagnetic transient (EMT) simulations of power systems require accurate representation of models in a wide range of frequencies. This of course applies to the representation of transmission lines, and the phase‐domain frequency‐dependent line model is often used to this end. The phase‐domain line model does not require modal transformation in EMT simulations but requires modal decomposition at its model identification stage, and there are cases where it fails to fix switchovers of propagation modes with respect to frequency. Thus, a frequency‐dependent line model which essentially avoids modal decomposition is desired. This paper studies the possibility of a frequency‐dependent line model based on the FDTD (Finite Difference Time Domain) method as a candidate which satisfies the above‐mentioned requirements. First, improvements regarding computational efficiency and numerical stability are made to Kordi's FDTD‐based frequency‐dependent line model. Then, the following points are clarified using the developed model: (i) Waveform deformations due to propagation modes with different velocities can be reproduced completely without modal decomposition; (ii) As the time step size becomes larger, waveforms obtained by the developed model become less accurate due to the embedded filter for numerical stability. These points assure, if the error due to the embedded filter is reduced, that the developed model can become a useful frequency‐dependent line model without model identification problems.  相似文献   

8.
This paper presents a scheme of small‐signal stability analysis for very large radial power systems. Generally, a radial power system can be easily classified as one main system and some external systems. Therefore, if accurate low‐order model of the external systems could be identified, the analysis effort for small‐signal stability can be reduced. Some dynamic reduction methods are proposed. Especially, the frequency‐domain least‐squares approximation methods, which are powerful and have high numerical reliability. This paper proposes a modal rebuild logic to improve the result obtained by the frequency‐domain least‐squares approximation methods. The proposed method provides high accuracy and a practical low‐order transfer function model. This paper introduces the usefulness of the proposed method with some numerical examples. In addition, merging sophisticated data handling and advanced applications in order to reduce human efforts is also discussed. This paper mentions the importance of automated node ID handling in order to realize the classification of system data into some partial data sets. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.  相似文献   

9.
A methodology is presented for the Krylov subspace‐based model order reduction of finite element models of electromagnetic structures with material properties and impedance boundary conditions exhibiting arbitrary frequency dependence. The proposed methodology is a generalization of an equation‐preserving Krylov model order reduction scheme for methodology for second‐order, linear dynamical systems. The emphasis of this paper is on the application of this method to the broadband model order reduction of planar circuits including lossy strips of arbitrary thickness and lossy reference planes. In particular, it is shown that the proposed model order reduction methodology provides for the accurately modelling of the impact of the frequency dependence of the internal impedance per unit length of the thick lossy strip on the electromagnetic response of the stripline structure over a very broad, multi‐GHz frequency band, extending all the way down to frequencies in the DC neighbourhood. In addition, the application of the proposed methodology to the broadband modelling of electromagnetic coupling between strips on either side of a lossy ground plane is demonstrated. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

10.
Model order reduction based on trajectory piecewise linearization (TPWL) is a beneficial technique for approximating nonlinear models. One efficient method for building projection matrix in TPWL reduction is by aggregation of projection matrices of linearization points (LPs). However, in this method, the size of projection matrix will also grow up by increasing the number of LPs, which yield the increment of the size of reduced model. In other words, the size of reduced model will depend on the number of LPs. In this paper, we will address this issue and propose two new strategies for obviating this problem. Contrarily to former works in TPWL modeling, we established a model via TWPL based on output weighting of parallel linear models. Then, we proposed two reduction strategies for suggested TPWL model. The first algorithm inspires from former works in this field but in a parallel structure that enable segregation of projection matrices whereas the second algorithm remedies the problem by considering the high‐order TPWL model as a unit linear model and reduces this model like a linear model but uses back projection method for constructing different outputs. The efficiency of methods is shown by comparison with former TPWL methods through vast simulations. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

11.
A multiphase dc‐dc converter is effective for miniaturization and achieving high‐power density in a switching power supply. However, its mathematical modeling becomes complex as the phase number of the circuit increases. This study proposes a new modeling method to derive a reduced‐order method in a simple manner. The frequency characteristics of the reduced‐order model are fit to those of the original mathematical model of the multiphase dc‐dc converter. Therefore, the efficacy of the proposed method is validated.  相似文献   

12.
To reduce boiler fuel cost, a new ELD (economic load dispatching) method based on a dynamic fuel cost model, which is more accurate than the conventional quadratic model, is proposed. First, an ARMA (autoregressive moving average) model, which is constant‐coefficient linear digital filter, is applied in order to supplement the quadratic model. We call this the supplemented model ARMA‐model‐supplemented quadratic model. By using this model, the model deviations from actual data have been reduced. Second, based on the ARMA‐model‐supplemented quadratic model, we formulated the ELD problem as a quadratic programming problem, where the objective function is the summation of all units' fuel costs over multiple time points and the constraints are the supply–demand balances, the upper and lower generation limits, and the ramp rate limits. This problem can be solved by the standard quadratic programming technique. We call this new ELD method BEST (boiler‐dynamics‐based economical load dispatching) method. Then, in order to make the problem size smaller, we propose a scheme to ignore all time points except for those corresponding to the peak, the bottom, and the steepest point on the forecasted load curve. We call this scheme the sample scheme. Finally, the BEST method with the sample scheme is evaluated by numerical simulations on the Kansai Electric Power Co. system and it is shown that the proposed method can reduce the calculation time without compromising the fuel cost. © 1999 Scripta Technica, Electr Eng Jpn, 127(1): 39–46, 1999  相似文献   

13.
A new method for gradient‐based optimization of electromagnetic systems using parametric sensitivity macromodels is presented. Parametric macromodels accurately describe the parameterized frequency behavior of electromagnetic systems and their corresponding parameterized sensitivity responses with respect to design parameters, such as layout and substrate parameters. A set of frequency‐dependent rational models is built at a set of design space points by using the vector fitting method and converted into a state‐space form. Then, this set of state‐space matrices is parameterized with a proper choice of interpolation schemes, such that parametric sensitivity macromodels can be computed. These parametric macromodels, along with the corresponding parametric sensitivity macromodels, can be used in a gradient‐based design optimization process. The importance of parameterized sensitivity information for an efficient and accurate design optimization is shown in the two numerical microwave examples. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

14.
The meshless radial point interpolation method (RPIM) in frequency domain for electromagnetic scattering problems is presented. This method promises high accuracy in a simple collocation approach using radial basis functions. The treatment of high‐order non‐reflecting boundary conditions for open waveguides is discussed and implemented up to fourth‐order. RPIM allows the direct calculation of high‐order spatial derivatives without the introduction of auxiliary variables. High‐order absorbing boundary conditions offer a choice of absorbing angles for each degree of spatial derivatives. For general applications, a set of these absorbing angles is calculated using global optimization. Numerical experiments show that at the same computational cost, the numerical reflections of the absorbing boundary conditions are much lower than conventional perfectly matched layers, especially at high angles of incidence. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

15.
针对Lagrange线性插值算法在谐波次数高的情况下误差过大和Lagrange抛物线插值算法在合并单元(MU)低采样频率下误差改进不明显,提出了一种改进算法。根据改进算法的计算思路,运用Matlab 7.0编程.对算法进行仿真和模拟。与线性插值算法相比,该算法大大降低了各采样点的相对误差,提高了电流、电压、功率幅值的测量精度;同时通过分析一种典型谐波信号,验证了在同样插值条件、计算量相当的情况下.加权算法在80Hz的低采样频率下,误差较二阶Lagrange算法有显著的改善.有效地抑制了谐渡对算法的影响。仿真结果表明该算法计算精度高.可以满足新型变电站智能设备的采样值信号接口技术的要求.  相似文献   

16.
The effects of model reduction on system characteristics, such as gain margin, phase margin, and bandwidth are investigated. A practical method is proposed so that the reduced models can approximate the frequency response of the original transfer function not only at S = 0 and S = ? but also at some specific points on the frequency response curve of the original system; thus the gain margin and/or phase margin can be kept unchanged. Examples are given, and comparisons with the methods given in current literature are made.  相似文献   

17.
This paper presents a novel system reduction method which makes it possible to consider the impact of photovoltaic (PV) penetration on transient stability precisely. The object system for system reduction can be aggregated into a simple equivalent circuit by using the proposed method. The equivalent circuit consists of a lumped load model, a lumped PV model, and three equivalent impedances. Using the equivalent circuit, power flow into the object system when the system voltage changes can be analyzed without repeated power flow calculation of the original system. In order to verify the proposed method, this paper presents a numerical example of transient stability analysis with a one‐generator‐to‐infinite‐bus system model. The results of analysis indicate that transient stability considering PV penetration can be analyzed with high accuracy with the proposed method.  相似文献   

18.
This paper is devoted to the problem of robust H filtering for a class of uncertain switched neutral systems subject to stochastic disturbance and time‐varying delay. Attention is focused on the design of a full‐order switched filter such that the filtering error system is robust mean‐square exponentially stable with a prescribed weighted H performance. On the basis of the average dwell time approach and the piecewise Lyapunov function technique, sufficient conditions for the solvability of this problem are obtained in terms of linear matrix inequalities. Then, by solving the corresponding linear matrix inequalities, the desired full‐order switched filter is derived for all admissible uncertainties, time‐varying delay, and stochastic disturbances. A numerical example is given to illustrate the effectiveness of the proposed method. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

19.
针对金属导体部分元等效电路模型的渐近波形估算(waveform evaluation, AWE)方法缩减的数值病态问题,提出使用基于Krylov子空间的Lanczos算法对系统模型进行缩减,将直接矩量显式计算转化为间接矩量隐式计算,将主导极点的抽取转化为主导特征值的抽取,并对系统近似误差限和程序自动终止准则进行了分析计算。在此基础上,给出了独立于频率之外的简化等效电路模型,得到了解耦电阻电感参数,并通过计算实例验证了该方法的正确性。该文的研究成果克服了AWE等直接矩量显式计算只能提取有限几条缩减支路的不足,极大提高了模型缩减方法的有效性和普适性。  相似文献   

20.
We address the problem of state estimation for Markov jump nonlinear systems and present a modified version of the multiple‐model and multiple‐hypothesis (M3H) algorithm to suboptimally solve it. In such systems, the exact filter must track an exponentially increasing number of possible trajectories. Therefore, practical solutions must approximate the exact filter trading off filter precision for computational speed. In this contribution, we employ Gaussian mixture reduction methods in the merging of hypotheses of the original M3H. Thus, information from both the analog and digital states is used to merge the hypotheses, whereas only information from the digital state is employed in the original method. In our numerical results, we show that the proposed method outperforms the original M3H when increased precision constraints are imposed to the filter.  相似文献   

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