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steady-state algorithm for switching power electronic devices

IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS 2001年第3期148卷 245-250页

作者： Contreras-Sampayo, JC Usaola-García, J Wood, AR Univ Carlos III Madrid Madrid 28911 Spain Univ Canterbury Dept Elect Engn Christchurch New Zealand

Obtaining the steady-state operation of a power electronic device by means of brute force computer simulation is not feasible in many practical cases. Fast steady-state algorithms that formulate the steady-state problem as a boundary problem and solve it using Newton's method have been proposed to overcome this difficulty. These algorithms are known as shooting algorithms. An extension of the shouting algorithm for piecewise linear circuits is provided. The complete Jarobian matrix that takes into account the switching instants variation is analytically derived fur a state variable formulation of the steady-state problem of a piecewise linear circuit. A computer program PWiseSS based on this algorithm is used to solve a previously proposed test circuit of difficult convergence as well as to solve a realistic six-pulse converter of interest to the power electronics engineer.

关键词： Relays and switches piecewise linear techniques linear network analysis Power convertors and power supplies to apparatus switching circuits shooting algorithms power convertors Newton method piecewise linear circuits steady-state algorithm power electronic device switching power semiconductor switches Algebra Jacobian matrices boundary problem Interpolation and function approximation (numerical analysis) Computer-aided circuit analysis and design six-pulse converter circuit analysis computing steady-state problem PWiseSS computer program Electronic engineering computing Newton's method Numerical analysis Linear network analysis and design software packages state variable formulation Power semiconductor devices Jacobian matrix Power electronics, supply and supervisory circuits

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A steady-state algorithm for Solving Expensive Multiobjective Optimization Problems With Nonparallelizable Evaluations

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IEEE TRANSACTIONS ON EVOLUTIONARY COMPUTATION 2023年第5期27卷 1544-1558页

作者： Rahi, Kamrul Hasan Singh, Hemant Kumar Ray, Tapabrata Univ New South Wales Sch Engn & Informat Technol Canberra ACT 2600 Australia

Expensive multiobjective optimization problems (EMOPs) refer to those wherein evaluation of each candidate solution incurs a significant cost. To solve such problems within a limited number of solution evaluations, surrogate-assisted evolutionary algorithms (SAEAs) are often used. However, existing SAEAs typically operate in a generational framework wherein multiple solutions are identified for evaluation in each generation. There exist relatively few proposals in steady-state framework, wherein only a single solution is evaluated in each iteration. The development of such algorithms is crucial to efficiently solve EMOPs for which the evaluation of candidate designs cannot be parallelized. Furthermore, regardless of the framework used, the performance of current SAEAs tends to degrade when the Pareto front (PF) of the problem has irregularities, such as extremely concave/convex segments, even for 2/3-objective problems. To contextualize the motivation of this study, the performance of a few state-of-the-art SAEAs is first demonstrated on some such selected problems. Then, to address the above research gaps, we propose a surrogate-assisted steady-state EA (SASSEA), which incorporates a number of novel elements, including: 1) effective use of model uncertainty information to aid the search, including the use of the probabilistic dominance and Mahalanobis distance;2) two-step infill identification using nondominance (ND) and distance-based selection;and 3) a shadow ND mechanism to avoid repeated selection and evaluation of dominated solutions. The efficacy of the proposed approach is demonstrated through extensive benchmarking on a range of test problems. It shows competitive performance relative to many state-of-the-art SAEAs, including both steady-state and generational approaches.

关键词： Infill strategy multiobjective algorithm steady-state algorithm surrogate-assisted optimization.

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Reliable and Efficient Procedure for steady-state Analysis of Nonautonomous and Autonomous Systems

Reliable and Efficient Procedure for Steady-State Analysis o...

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作者： Dobes, J. Brno University of Technology

The majority of contemporary design tools do not still contain steady-state algorithms, especially for the autonomous systems. This is mainly caused by insufficient accuracy of the algorithm for numerical integration, but also by unreliable steady-state algorithms themselves. Therefore, in the paper, a very stable and efficient procedure for the numerical integration of nonlinear differential-algebraic systems is defined first. Afterwards, two improved methods are defined for finding the steady state, which use this integration algorithm in their iteration loops. The first is based on the idea of extrapolation, and the second utilizes nonstandard time-domain sensitivity analysis. The two steady-state algorithms are compared by analyses of a rectifier and a C-class amplifier, and the extrapolation algorithm is primarily selected as a more reliable alternative. Finally, the method based on the extrapolation naturally cooperating with the algorithm for solving the differential-algebraic systems is thoroughly tested on various electronic circuits: Van der Pol and Colpitts oscillators, fragment of a large bipolar logical circuit, feedback and distributed microwave oscillators, and power amplifier. The results confirm that the extrapolation method is faster than a classical plain numerical integration, especially for larger circuits with complicated transients.

关键词： Numerical integration steady-state algorithm period extrapolation epsilon-algorithm sensitivity analysis.

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Controlling the thermal environment in hot spots of buried power cables

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EUROPEAN TRANSACTIONS ON ELECTRICAL POWER 2007年第5期17卷 427-449页

作者： Klimenta, D. Nikolajevic, S. Sredojevic, M. Pristina Univ Kosovska Mitrovica Fac Engn Kosovska Mitrovica 38720 Serbia Univ Belgrade Fac Elect Engn Belgrade 11000 Serbia Inst Elect Engn Nikola Tesla Belgrade 11000 Serbia

An approach to numerical modelling of temperature distributions around buried power cables using finite element analysis is presented in this paper.-The finite element algorithms are based on time-dependent heat sources of the environment and temperature-dependent material properties of the cables. The nonlinear steady-state and transient heat transfer algorithms are applied to the problem of controlling thermal environment in an actual hot spot of a 110kV cable line installed in Belgrade, Republic of Serbia. Moreover, this paper outlines the influence of an underground heating pipeline on ampacities of the cable line, and two retrofitting procedures for optimising the thermal properties of cable environment. Two suggested procedures for thermal optimisation of the actual hot spot are: the use of a new-mixed corrective backfill and the use of quartz sand. Finally, actual test cases using the measured data indicate the possibilities of using the proposed algorithms. Copyright (C) 2006 John Wiley & Sons, Ltd.

关键词： finite element method heating pipeline hot spot power cables steady-state algorithm transient algorithm

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Effects of sliding on rolling contact fatigue of railway wheels

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FATIGUE & FRACTURE OF ENGINEERING MATERIALS & STRUCTURES 2013年第6期36卷 515-525页

作者： Langueh, A. M. G. Brunel, J. -F. Charkaluk, E. Dufrenoy, P. Tritsch, J. -B. Demilly, F. Univ Lille Nord France F-59000 Lille France ECLille LML F-59650 Villeneuve Dascq France USTL LML F-59650 Villeneuve Dascq France CNRS UMR 8107 F-59650 Villeneuve Dascq France GHH Valdunes F-59125 Trith St Leger France

This paper proposes a numerical approach based on a steady-state algorithm to predict the rolling contact fatigue crack initiation in railway wheels in practical conditions. This work suggests taking into account the cyclic hardening of the wheel's material and one of its originality is to conduct a complete numerical approach whatever the loading level. The main stages are the characterization and modelling of the material behaviour, the determination of the stressstrain fields using a numerical steady-state method and the application of a high cycle fatigue criterion. Computations were made with the Abaqus FE commercial software. Three cases are studied: rolling with or without sliding and skating. The numerical results give several types of mechanical responses: elastic or plastic shakedown. Otherwise, the results show that the location where the shear stress is maximal is not the same as where the risk of crack is the highest.

关键词： hardening rolling contact fatigue shakedown steady-state algorithm

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Fast estimation of main intermodulation products using Volterra series

Fast estimation of main intermodulation products using Volte...

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IEEE International Conference on Integrated Circuit Design and Technology

作者： Dobes, Josef Czech Tech Univ Dept Radio Engn Prague 16627 6 Czech Republic

ISBN: (纸本)9781424407569

The most accurate procedure for computing the intermodulation products is to find a steady-state period of the signal, and then to determine the spectrum by means of fast Fourier transform. However, this method needs a time-consuming numerical integration over many periods of the faster signal even for accelerated extrapolation methods for determining the steady state. In the paper, an efficient method for a fast estimation of the main intermodulation products is presented. The method uses higher-order Volterra series in a simple multistep algorithm, which is compatible with a typical structure of the frequency-domain part of software tools. The method is demonstrated by an illustrative example first, which clearly shows possible incorrect interpretation of the Volterra series. Afterwards, the efficiency of the algorithm is demonstrated by a fast estimation of the main intermodulation products of a low-voltage low-power CMOS RF four-quadrant multiplier.

关键词： steady-state algorithm fast Fourier transform numerical integration Volterra series four-quadrant multiplier

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Influence of the steel grades on rolling contact fatigue of railway wheels

Influence of the steel grades on rolling contact fatigue of ...

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11th International Conference on the Mechanical Behavior of Materials (ICM)

作者： Langueh, A. Brunel, J-F. Charkaluk, E. Dufrenoy, P. Demilly, F. Univ Lille Nord France F-59000 Lille France ECLille LML F-59650 Villeneuve Dascq France USTL LML F-59650 Villeneuve Dascq France CNRS UMR 8107 F-59650 Villeneuve Dascq France GHH Valdunes F-59125 Trith Saint Leger France

The aim of this work is to develop a numerical approach which is able to include the inelastic material behavior in order to compare the different steel grades influence on rolling contact fatigue of railways wheels according to practical conditions. The main stages are the identification of the material behavior using genetic algorithms, the determination of the stress-strain fields by steady-state method and the application of a fatigue criterion. Two steels usually used for the manufacturing of wheels have been studied: R7T and R9T. Their influence has been numerically studied. Results show that the local stress-strain path along the streamline and the fatigue stress path differ depending on the steel grades and consequently the risk of damage can be affected, allowing a classification of the material grades face the risk on rolling contact fatigue. (C) 2011 Published by Elsevier Ltd. Selection and peer-review under responsibility of ICM11

关键词： rolling contact fatigue shakedown plasticity steady-state algorithm genetic algorithm

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Rolling contact fatigue of railways wheels: influence of steel grade and sliding conditions

Rolling contact fatigue of railways wheels: influence of ste...

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10th International Fatigue Conference

作者： Brunel, J-F. Charkaluk, E. Dufrenoy, P. Demilly, F. CNRS Lab Mecan Lille UMR 8107 F-59655 Villeneuve Dascq France GHH Valdunes F-59125 Valdunes France

The aim of this work is to develop a numerical approach which is able to compare the different steel grades influence on rolling contact fatigue of railways wheels according to practical conditions. The main stages are the identification of the material behavior, the determination of the stress-strain fields and the application of a fatigue criterion. Two steels usually used for the manufacturing of wheels have been studied, R9T and 50CrMo4. Their influence has been numerically studied. Results show that the threshold of elastic and plastic shakedown differs depending on the steel grades and consequently the risk of damage can be affected. This methodology allows a classification of the material grades face the risk on rolling contact fatigue. (C) 2010 Published by Elsevier Ltd.

关键词： rolling contact fatigue shakedown steady-state algorithm plasticity

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Using Volterra Series for an Estimation of Fundamental Intermodulation Products

Using Volterra Series for an Estimation of Fundamental Inter...

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作者： Dobes, J. Brno University of Technology

The most precise procedure for determining the intermodulation products is to find a steady-state period of the signal first, and then to calculate its spectrum by means of the fast Fourier transform. However, this method needs time-consuming numerical integration over many periods of the faster signal even for enhanced methods for finding the steady state. In the paper, an efficient method for fast estimation of the fundamental intermodulation products is presented. The method uses Volterra series in a simple multistep algorithm which is compatible with a typical structure of the frequency-domain part of circuit simulators. The method is demonstrated by an illustrative testing circuit first, which clearly shows possible incorrect interpretation of the Volterra series. Thereafter, practical usage of the algorithm is demonstrated by fast estimation of the main intermodulation products of a low-voltage low-power RF CMOS fourquadrant multiplier.

关键词： steady-state algorithm fast Fourier transform numerical integration Volterra series CMOS RF multiplier

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Influence of the steel grades on rolling contact fatigue of railway wheels

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Procedia Engineering 2011年 10卷 2627-2632页

作者： A. Langueh J-F. Brunel E. Charkaluk P. Dufrénoy F. Demilly Univ Lille Nord de France F-59000 Lille France USTL LML F-59650 Villeneuve d’Ascq France CNRS UMR 8107 F-59650 Villeneuve d’Ascq France ECLille LML F-59650 Villeneuve d’Ascq France GHH Valdunes F-59125 Trith Saint Leger France

关键词： rolling contact fatigue shakedown plasticity steady-state algorithm genetic algorithm

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