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10th IEEE Electronics System-Integration Technology Conference (ESTC)

作者： Pradhan, Abinash Grosso, Giovanna Kurukuru, Varaha Satya Bharath Romano, Claudio Petrella, Roberto Silicon Austria Labs GmbH Villach Austria Ideas & Mot Srl Turin Italy Univ Udine DPIA Udine Italy

ISBN: (纸本)9798350390377;9798350390360

In electric vehicle power electronics (PE) systems, particularly for traction inverters, it is pivotal to effectively manage electrical, thermal, and mechanical stresses experienced by Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs), under different operational conditions. Analysis of these stresses through simulations, enables initial assessments and optimizations before construction of physical prototypes and experimental testing. However, conventional simulation techniques like Computational Fluid Dynamics (CFD) demand significant processing resources and time, being disadvantageous in PE system-level simulations. A linear time-invariant (LTI) thermal reduced order model (ROM) of an inverter phase leg module based on embedded GaN HEMT dies is considered in this research, as derived from 3D CFD transient thermal simulations. The ROM is coupled with a PLECS/MATLAB simulation of a full Permanent Magnet Synchronous Motor (PMSM) traction drive, including temperature dependency of GaN HEMT's drain source on-resistance, thus allowing fast coupled electrothermal simulations and accurate estimation of GaN HEMT temperature changes in response to generated power losses during varying torque/speed operations. The mechanical response of the inverter phase leg module in response to a critical thermal loading scenario (i.e., rapid acceleration and deceleration) highlights potential permanent deformation of the topside copper metalization layers and microvia interconnects. The proposed workflow allows a fast coupled electrothermal and thermomechanical simulation framework for optimization and rapid identification of critical conditions of next generation PE systems.

关键词： Electrothermal analysis GaN HEMT linear time-invariant reduced order model traction inverter thermo-mechanical stress

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Development and simulation of fuzzy adaptive PID control for time variant and invariant systems

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INTERNATIONAL JOURNAL OF SYSTEM ASSURANCE ENGINEERING AND MANAGEMENT 2021年 1-9页

作者： Wang, Xing Univ Chinese Acad Sci Beijing 100049 Peoples R China Taiyuan Univ Sci & Technol Taiyuan 030024 Shanxi Peoples R China

With the modern computer technology development, power electronic technology, the motor control performance is getting better and better and the motor speed control technology is increasingly improved. The predictive control's successful applications utilizing fuzzy models have for linear time-invariant systems. With the development of proportional-integral-derivative (PID) system, many efforts are required for linear time variant systems as well as time-invariant systems. The PID controller architecture is practical in nonlinear industrial processes and it is the main features of the classical PID controllers which avoid lengthy and fuzzy systems. In order to improve the dynamic and static performance of Brushless DC motor control system, this paper combines fuzzy control with PID control, designs a fuzzy adaptive PID control system, and builds a Matlab/Simulink system simulation platform. The results show that the fuzzy adaptive PID control proposed in this paper is much better than the traditional PID control, and its adjustment speed is 0.15 s, which is almost twice as fast as the traditional PID control. The proposed fuzzy adaptive PID has stronger robustness and adaptability than traditional PID. By adjusting the appropriate parameters, the system achieves ultra-fast start without overshoot. Through the analysis and comparison of the simulation results, it is obtained that the fuzzy adaptive PID has superior performance, fast system response and no overshoot.

关键词： Fuzzy adaptive PID Brushless DC motor MATLAB Simulink PID controllers PID adaptability linear time-invariant

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Equivalent Multiple dq-Frame Model of the MMC Using Dynamic Phasor Theory in the αβz-Frame

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IEEE TRANSACTIONS ON POWER DELIVERY 2020年第6期35卷 2916-2927页

作者： Sakinci, Ozgur Can Beerten, Jef Katholieke Univ Leuven Dept Elect Engn ESAT ELECTA Res Grp B-3000 Leuven Belgium EnergyVille B-8310 Genk Belgium

This article introduces an equivalent multiple dqframemodel of themodular multilevel converter (MMC) that is derived from a dynamic phasor based small-signal state-space MMC model in the stationary alpha beta z frame. When compared to a model in the stationary ABC frame, the order of the model in the alpha beta z frame can be reduced for balanced operation, during which some voltage, and current harmonics are inherently separated in an alpha beta z representation. The proposed method enables further model order reduction through a generalized transformation towards multiple dq-frames. The development of the model, and the generalized transformation are explained in detail, and the obtained equivalent multiple dq-framemodels are verified against a nonlinear averaged model in MATLAB/Simulink. An eigenvalue-based small-signal stability analysis highlights the effect of higher-order harmonics in system-level small-signal stability studies, and two case studies of active harmonic suppression illustrate how the presented model allows an in-depth investigation of the impact of extended control functionalities on the small-signal stability.

关键词： Dynamic phasor Clarke transform Park transform small-signal stability modular multilevel converter linear time-invariant reduced order model state-space modeling

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Stabilization of linear time-varying reduced-order models: A feedback controller approach

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING 2020年第24期121卷 5490-5510页

作者： Mojgani, Rambod Balajewicz, Maciej Univ Illinois Dept Aerosp Engn Champaign IL USA

Many of the commonly used methods in model-order reduction do not guarantee stability of the reduced-order model. This article extends the eigenvalue reassignment method of stabilization of linear time-invariant ROMs, to the more general case of linear time-varying systems. Through a postprocessing step, the ROM is controlled to ensure the stability while enhancing/maintaining its accuracy using a constrained nonlinear lease-square minimization problem. The controller and the input signals are defined at the algebraic level, using left and right singular vectors of the reduced system matrices. The choice provides a control on the upper bound of the growth of the energy of the reduced system. The optimization problem is applied to several time-invariant, time-periodic, and time-varying problems, and the reproductive and predictive capabilities of the proposed method, with respect to novel inputs and the system parameters, are evaluated.

关键词： linear time-invariant linear time-periodic linear time-varying reduced-order model singular value decomposition stabilization

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Mechanical vibration control and second-order LTI system analysis of an SDOF with harmonic motion 4

Mechanical vibration control and second-order LTI system ana...

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4th International Seminar on Research of Information Technology and Intelligent Systems (ISRITI)

作者： Ayvaci, Omer Szulczynski, Pawel Poznan Univ Tech Fac Comp & Telecommun Poznan Poland Poznan Univ Tech Fac Control Robot & Elect Engn Poznan Poland

ISBN: (纸本)9781665401517

It is critical to analyze vibration because of the prevalence of vibration in engineering. Our primary objective is to find a new method to analyze mechanical system vibrations under different circumstances with a single degree of freedom (SDOF). The mass-spring-damping (MSD) system's mathematical structure will be used as a baseline for analyzing the SDOF system. The second-order homogeneous linear time-invariant (LTI) system (under-damped, critically-damped, and overdamped) is analyzed and given in this conference paper. The findings include identified parameters such as dynamic magnetic variables and step responses. Besides, a PID controller is optimized for vibration.

关键词： second-order system steady-state transient-state vibration linear time-invariant

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Feasibility of spiral fMRI based on an LTI gradient model

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NEUROIMAGE 2021年 245卷 118674-118674页

作者： Graedel, Nadine N. Kasper, Lars Engel, Maria Nussbaum, Jennifer Wilm, Bertram J. Pruessmann, Klaas P. Vannesjo, S. Johanna Univ Oxford Wellcome Ctr Integrat Neuroimaging Nuffield Dept Clin Neurosci FMRIB Oxford England Swiss Fed Inst Technol Inst Biomed Engn Zurich Switzerland Univ Zurich Zurich Switzerland Univ Zurich Inst Biomed Engn Translat Neuromodeling Unit Zurich Switzerland Swiss Fed Inst Technol Zurich Switzerland

Spiral imaging is very well suited for functional MRI, however its use has been limited by the fact that artifacts caused by gradient imperfections and B 0 inhomogeneity are more difficult to correct compared to EPI. Effective correction requires accurate knowledge of the traversed k-space trajectory. With the goal of making spiral fMRI more accessible, we have evaluated image reconstruction using trajectories predicted by the gradient impulse response function (GIRF), which can be determined in a one-time calibration step. GIRF-predicted reconstruction was tested for high-resolution (0.8 mm) fMRI at 7T. Image quality and functional results of the reconstructions using GIRF-prediction were compared to reconstructions using the nominal trajectory and concurrent field monitoring. The reconstructions using nominal spiral trajectories contain substantial artifacts and the activation maps contain misplaced activation. Image artifacts are substantially reduced when using the GIRF-predicted reconstruction, and the activation maps for the GIRF-predicted and monitored reconstructions largely overlap. The GIRF reconstruction provides a large increase in the spatial specificity of the activation compared to the nominal reconstruction. The GIRF-reconstruction generates image quality and fMRI results similar to using a concurrently monitored trajectory. The presented approach does not prolong or complicate the fMRI acquisition. Using GIRF-predicted trajectories has the potential to enable high-quality spiral fMRI in situations where concurrent trajectory monitoring is not available.

关键词： Functional MRI High-resolution fMRI Spiral imaging Single-shot spiral linear time-invariant GIRF

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Generalized Dynamic Phasor Modeling of the MMC for Small-Signal Stability Analysis

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IEEE TRANSACTIONS ON POWER DELIVERY 2019年第3期34卷 991-1000页

作者： Sakinci, Ozgur Can Beerten, Jef Katholieke Univ Leuven Dept Elect Engn ELECTA B-3000 Leuven Belgium EnergyVille B-8310 Genk Belgium

This paper introduces a dynamic phasor model of a half-bridge modular multilevel converter based on variables in the stationary ABC frame. The application of the dynamic phasor theory makes it possible to use converter eigenvalues to study the effect of steady-state harmonics present in the modular multilevel converter (MMC) on its small-signal stability, since the model is inherently time invariant. Relying on a linear transformation, this paper uses a new set of variables with a modified frequency content, which results in lower order dynamic phasor models. A nonlinear dynamic phasor model is developed and linearized. The linear model is compared with a nonlinear averaged MMC model in time domain. Stability analysis bymeans of eigenvalues and participation factors is carried out for dynamic phasor models that include different frequency content, and the effect of the circulating current suppression controller is analyzed.

关键词： Dynamic phasor small-signal stability modular multilevel converter linear time-invariant modal analysis

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Identification of FIR Models for LTI Multiscale Systems using Sparse Optimization Techniques

Identification of FIR Models for LTI Multiscale Systems usin...

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5th IFAC Conference on Advances in Control and Optimization of Dynamical Systems (ACODS)

作者： Pinnamaraju, Vivek S. Tangirala, Arun K. Indian Inst Technol Madras Madras 600036 Tamil Nadu India

Finite impulse response (FIR) models are very popular in process industries because of their simple model structure, flexibility to explain arbitrary complex stable linear dynamics and finally their ease of implementation in on-line applications. In general, identification of FIR models requires large number of parameters to be estimated. In case of systems with multiple time scales, the length of FIR model structure under conventional uniform sampling becomes arbitrarily high due to simultaneous presence of fast and slow dynamics. This results in more variability in the estimated parameters when the conventional methods such as ordinary least squares are used. In this work, the FIR model estimation problem is formulated as a sparse optimization problem, where the sparse representation of impulse response coefficients for linear-time invariant multiscale systems in the time-frequency domain is exploited in order to explain the overall FIR model effectively with fewer number of coefficients and thereby incurring less variability in the estimated parameters. The effectiveness of proposed methodology is demonstrated by means of simulation case studies. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Multiscale linear time-invariant FIR Models System Identification Parsimony Sparse Optimization Wavelets

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Wavelet based Steglitz Mc-Bride algorithm for Identification of Multiscale Output-Error Models

Wavelet based Steglitz Mc-Bride algorithm for Identification...

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18th IFAC Symposium on System Identification (SYSID)

作者： Pinnamaraju, Vivek S. Tangirala, Arun K. Indian Inst Technol Madras Madras 600036 Tamil Nadu India

Identification of output-error models for systems with multiple time scales is known to be a challenging problem due to the spread of dynamics across a wide range of time scales. The wide separation in time constants of the system forces one to deal with unusually fast sampling rates for slow dynamics. In general, output-error model identification of multiscale systems using prediction-error minimization suffers whenever they are initialized with auto regressive exogenous (ARX) model parameter estimates owing to the sensitivity of ARX models at fast sampling. In the present work, it is observed that the classical Steglitz Mc-Bride (SM) algorithm can serve as an excellent alternative for identification of simple multiscale systems. Despite its advantages, it is seen to yield unstable models at times (related to the sensitivity of ARX estimation) and sometimes converges to a secondary optima. In this work, a multiscale SM algorithm, which respects the multiscale nature of data generating process, is proposed in order to reduce the sensitivity issues arising due to fast sampling. The proposed methodology is observed to yield good results for multiscale systems in terms of obtaining stable models and faster convergence. The performance of the proposed method is demonstrated on three simulation examples and the results are compared with traditional methods. (C) 2018, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Discrete-time model Output error models System Identification Multiscale linear time-invariant Wavelet transform

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Transfer matrix method for deriving transfer functions of LTI systems 6

Transfer matrix method for deriving transfer functions of LT...

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6th International Conference on Electronics and Information Engineering (ICEIE)

作者： Jeng, S. L. Lue, B. H. Chieng, W. H. Ta Hua Univ Sci & Technol Dept Elect & Elect Engn Qionglin Township Hsinchu County Taiwan Natl Chiao Tung Univ Dept Mech Engn Hsinchu 30050 Taiwan

ISBN: (纸本)9781510600294

This paper presents a new method, called the transfer matrix method for obtaining transfer functions among the state variables of a linear time-invariant (LTI) system defined in either a block diagram or the corresponding signal flow graph. The procedures introduced in this paper for obtaining the transfer function require only knowledge on matrix operations, which are easy to explain and remember. Advanced control engineers can automate the symbolic matrix operation by using existing software such as Mathematica.

关键词： Block diagram linear time-invariant signal flow graph transfer function

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