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Optimised active harmonic elimination technique for three-level T-type inverters

IET POWER ELECTRONICS 2013年第3期6卷 425-433页

作者： Aghdam, Ghasem Hosseini Huawei Technol Sweden AB Ctr Res & Dev S-16440 Kista Sweden

This study develops a pulse-width modulation (PWM) method that is referred the optimised active harmonic elimination (AHE) technique to eliminate more harmonics with minimum switching frequency for three-level T-type converter (3 L-T2C) based on the fundamental frequency switching control method. First, homotopy algorithm is applied to non-linear transcendental equations to eliminate low-order harmonics and to determine switching angle sets for selective harmonic elimination PWM in 3 L-T2C. The characteristics of the multiple solutions in terms of harmonic distribution, and total harmonic distortion (THD) are investigated. Then a detailed analysis of optimised AHE-PWM technique is presented to cancel more harmonics in 3 L-T2C using harmonic compensation strategy. A switching angle solution set that gives the lowest THD for optimised AHE-PWM is derived and the effectiveness of the control method is verified through extensive simulation studies. Finally, selected experimental results are reported to verify and validate the theoretical and simulation findings.

关键词： compensation frequency control harmonic distortion harmonics suppression nonlinear equations PWM invertors time-varying systems optimised active harmonic elimination technique three-level T-type inverters pulse-width modulation method PWM method switching frequency 3 L-T2C fundamental frequency switching control method homotopy algorithm nonlinear transcendental equations low-order harmonics elimination switching angle sets harmonic distribution total harmonic distortion THD optimised AHE-PWM technique harmonic compensation strategy compensation frequency control harmonic distortion harmonics suppression nonlinear equations PWM invertors time-varying systems optimised active harmonic elimination technique three-level T-type inverters pulse-width modulation method PWM method switching frequency 3 L-T2C fundamental frequency switching control method homotopy algorithm nonlinear transcendental equations low-order harmonics elimination switching angle sets harmonic distribution total harmonic distortion THD optimised AHE-PWM technique harmonic compensation strategy

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Elimination of Selective Harmonics in a Multi-Level Inverter

Elimination of Selective Harmonics in a Multi-Level Inverter

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7th International Conference on Intelligent Systems and Control (ISCO)

作者： Dhal, P. K. Rajan, C. Christober Asir Sathyabama Univ Madras Tamil Nadu India Puducherry Engn Coll Pondicherry India

ISBN: (纸本)9781467346016;9781467343596

This paper presents a selective harmonics elimination in Multi-Level Inverter. The basic concept of this reduction is to eliminate specific harmonics, which are generally of the lowest orders, with an appropriate choice of switching angles. This paper employs homotopy algorithm to solve the transcendental equations for finding the switching angles. This method solves the non-linear transcendental equations with a much simpler formulation and without complex analytical calculations for any number of voltage levels. Also several informative simulation results verify the validity and effectiveness of the proposed algorithm.

关键词： Multilevel Inverter homotopy algorithm Optimization Technique

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Numerical construction of LISS Lyapunov functions under a small-gain condition

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MATHEMATICS OF CONTROL SIGNALS AND SYSTEMS 2012年第1-2期24卷 3-32页

作者： Geiselhart, Roman Wirth, Fabian Univ Wurzburg Inst Math D-97074 Wurzburg Germany

In the stability analysis of large-scale interconnected systems it is frequently desirable to be able to determine a decay point of the gain operator, i.e., a point whose image under the monotone operator is strictly smaller than the point itself. The set of such decay points plays a crucial role in checking, in a semi-global fashion, the local input-to-state stability of an interconnected system, and in the numerical construction of a LISS Lyapunov function. We provide a homotopy algorithm that computes a decay point of a monotone operator. For this purpose we use a fixed-point algorithm and provide a function whose fixed points correspond to decay points of the monotone operator. The advantage over an earlier algorithm is demonstrated. Furthermore, an example is given which shows how to analyze a given perturbed interconnected system.

关键词： homotopy algorithm Monotone operator LISS Lyapunov function Interconnected system Small-gain condition

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Transformer Fault Diagnosis Based on homotopy BP algorithm

Transformer Fault Diagnosis Based on Homotopy BP Algorithm

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2009 9th International Conference on Electronic Measurement & Instruments(第九届电子测量与仪器国际会议 ICEMI'2009)

作者： Jiyin Zhao Ruirui Zheng Jianpo Li college of electromechanical information engineering Dalian Nationalities UniversityDalianChina college of communication engineering Jilin UniversityChangchunChina college of information engineering Northeast Dianli UniversityJilinChina

ISBN: (纸本)9781424438631;9781424438624

Power transformer fault diagnosis is the key technology of electric power system. To solve the problem that BP neural network easily trapped in local minima points, a non-linear homotopy based BP neural network is introduced in power transformer fault diagnosis. The neural network parameters were chosen after several experiments. LM optimization algorithm trained the non-linear homotopy BP neural network DAG data was processed by cumulative frequency method and sent to BP neural network. The neural network proposed in this paper had a better performance on convergent speed and avoid trapped in local minima points. The power transformer fault diagnosis experiments and gases regression curve analysis both demonstrate that fault diagnosis precision of non-linear BP neural network was higher than standard BP network.

关键词： power transformer fault diagnosis dissolved gas analysis BP neural network homotopy algorithm

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Numerical Construction of LISS Lyapunov Functions under a Small Gain Condition

Numerical Construction of LISS Lyapunov Functions under a Sm...

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50th IEEE Conference of Decision and Control (CDC)/European Control Conference (ECC)

作者： Geiselhart, Roman Wirth, Fabian Univ Wurzburg Inst Math D-97070 Wurzburg Germany

ISBN: (纸本)9781612848013

We provide a homotopy algorithm that computes a decay point of a monotone operator, i.e., a point whose image under the monotone operator is strictly smaller than the preimage. For this purpose we use a fixed point algorithm and provide a function whose fixed points correspond to decay points of the monotone operator. This decay point plays a crucial role in checking, in a semi-global fashion, the local input-to-state stability of an interconnected system numerically and in the numerical construction of local input-to-state stability (LISS) Lyapunov functions. We give some improvements of this algorithm and show the advantage to an earlier approach based on the algorithm of Eaves.

关键词： homotopy algorithm monotone operator LISS Lyapunov function interconnected system small gain condition

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Numerical Construction of LISS Lyapunov Functions under a Small Gain Condition

Numerical Construction of LISS Lyapunov Functions under a Sm...

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IEEE Conference on Decision and Control

作者： Roman Geiselhart Fabian Wirth Institute for Mathematics University of Wurzburg Germany

ISBN: (纸本)9781612848006

关键词： homotopy algorithm monotone operator LISS Lyapunov function interconnected system small gain condition

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On the structure of the inverse kinematics map of a fragment of protein backbone

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JOURNAL OF COMPUTATIONAL CHEMISTRY 2008年第1期29卷 50-68页

作者： Milgram, R. J. Liu, Guanfeng Latombe, J. C. Stanford Univ Dept Math Stanford CA 94305 USA Stanford Univ Dept Comp Sci Stanford CA 94305 USA

Loop closure in proteins requires computing the values of the inverse kinematics (IK) map for a backbone fragment with 2n >= 6 torsional degrees of freedom (dofs). It occurs in a variety of contexts, e.g., structure determination from electron-density maps, loop insertion in homology-based structure prediction, backbone tweaking for protein energy minimization, and the study of protein mobility in folded states. The first part of this paper analyzes the global structure of the IK map for a fragment of protein backbone with 6 torsional dofs for a slightly idealized kinematic model, called the canonical model. This model, which assumes that every two consecutive torsional bonds C-alpha-C and N-C-alpha are exactly parallel, makes it possible to separately compute the inverse orientation map and the inverse position map. The singularities of both maps and their images, the critical sets, respectively, decompose SO(3) x R-3 into open regions where the number of IK solutions is constant. This decomposition leads to a constructive proof of the existence of a region in R-3 x SO(3) where the IK of the 6-dof fragment attains its theoretical maximum of 16 solutions. The second part of this paper extends this analysis to study fragments with more than 6 torsional dofs. It describes an efficient recursive algorithm to sample IK solutions for such fragments, by identifying the feasible range of each successive torsional dof. A numerical homotopy algorithm is then used to deform the IK solutions for a canonical fragment into solutions for a noncanonical fragment. Computational results for fragments ranging from 8 to 30 dofs are presented. (C) 2007 Wiley Periodicals, Inc.

关键词： protein backbone inverse kinematics loop closure singularity analysis conformation space sampling homotopy algorithm

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Theory of globally convergent probability-one homotopies for nonlinear programming

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SIAM JOURNAL ON OPTIMIZATION 2001年第3期11卷 761-780页

作者： Watson, LT Virginia Polytech Inst & State Univ Dept Comp Sci & Math Blacksburg VA 24061 USA

For many years globally convergent probability-one homotopy methods have been remarkably successful on di cult realistic engineering optimization problems, most of which were attacked by homotopy methods because other optimization algorithms failed or were ineffective. Convergence theory has been derived for a few particular problems, and considerable fixed point theory exists, but generally convergence theory for the homotopy maps used in practice for nonlinear constrained optimization has been lacking. This paper derives some probability-one homotopy convergence theorems for unconstrained and inequality constrained optimization, for linear and nonlinear inequality constraints, and with and without convexity. Some insight is provided into why the homotopies used in engineering practice are so successful, and why this success is more than dumb luck. By presenting the theory as variations on a prototype probability-one homotopy convergence theorem, the essence of such convergence theory is elucidated.

关键词： constrained optimization globally convergent homotopy algorithm nonlinear equations probability-one homotopy

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Computing equilibria in stochastic finance economies

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Computational Economics 2000年第1-2期15卷 145-172页

作者： Kubler, Felix Schmedders, Karl Department of Economics Yale University New Haven U.S.A. Hoover Institution Stanford University USA

We describe a homotopy algorithm for the computation of equilibria in Stochastic Finance Economies. The algorithm solves a nonlinear system of equations consisting of the first-order conditions of the agents' utility maximization problems and market-clearing conditions. Moreover, we discuss the use of a straightforward homotopy approach for local comparative statics. Using our methods we evaluate price, volatility, and welfare effects of options in incomplete asset markets.

关键词： homotopy algorithm Incomplete markets Index theorem Stochastic finance economy

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PARALLEL homotopy algorithm FOR SYMMETRICAL LARGE SPARSE EIGENPROBLEMS

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 1995年第1-2期60卷 77-100页

作者： HUANG, LJ LI, TY ROCKFORD COLL DEPT MATHROCKFORDIL 61108 MICHIGAN STATE UNIV DEPT MATHE LANSINGMI 48824

In this paper, the homotopy continuation method is applied to solve the eigenproblem Ax = lambda x, lambda is an element of R, x is an element of R(n)\{0} or a symmetric large sparge matrix A. A one-parameter family o... 详细信息

In this paper, the homotopy continuation method is applied to solve the eigenproblem Ax = lambda x, lambda is an element of R, x is an element of R(n)\algorithm or a symmetric large sparge matrix A. A one-parameter family of matrices A(t) = tA + (1 - t) D is introduced and the eigenproblem A(t)x(t) = lambda(t)x(t) is considered for t is an element of [0, 1]. We discuss the problem of choosing an optimal starting matrix A(0) = D and consider the regularity and bifurcation problem of lambda(t) and x(t). A homotopy continuation algorithm is constructed and implemented on both parallel and vector machines for several types of matrices. The numerical experiments show that our method is efficient and highly parallel.

关键词： EIGENPROBLEMS homotopy algorithm PARALLELISM

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