Navegando por Assunto "Buck converter"

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Acesso aberto (Open Access)
Performance evaluation of robust parametric control strategies applied on suppression of oscillations effects due to constant power loads in multi-converter buck-buck systems
(Universidade Federal do Pará, 2018-06-11) MARCILLO, Kevin Eduardo Lucas; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608
Multi-converter electronic systems are becoming widely used in many industrial applications; therefore, the stability of the cascaded system is a big concern to real-world power supplies applications. Instability in cascaded systems may occur due to the constant power load (CPL), which is a behavior of the tightly regulated converters. CPLs exhibit incremental negative resistance behavior causing a high risk of instability in interconnected converters; therefore, the mitigation of this problem is an important issue in the multiple-stage switched mode power supply design. Thus, it is important to guarantee stability of the whole system. However, some difficulties remains besides the CPL, e.g., non-linearities due to the inductive element and uncertainties due to imprecision of mathematical models and/or variation of nominal values of the discrete elements that compose the DC/DC buck converter. Aiming to evaluate the performance of the proposed robust methodologies in this work to mitigate the instability problem caused by a CPL, several tests were developed by using an experimental plant and Matlab/Simulink, when the multi-converter buck-buck system is subjected a variation of power reference. The results show the improved performance of the proposed methodologies.
Acesso aberto (Open Access)
Projeto de controlador baseado em inequações matriciais lineares aplicado a um sistema multiconversor sujeito à incertezas paramétricas
(Universidade Federal do Pará, 2024-08-23) SILVA JUNIOR, Carlos Roozenbergh Porto da; BARRA JUNIOR, Walter; http://lattes.cnpq.br/0492699174212608
Conversion systems are critically important devices in electrical systems across various environments, especially in modern times, as multiple components with different voltage levels and sources are interconnected within a single system. Consequently, dynamic study methods of this network are examined using approaches that simplify the network based on speed modes and switching of other conversion systems, wherein fast systems are simplified to constant power loads (CPL). This method evaluates the network’s stability conditions. The study reveals that CPLs act as negative incremental resistances, and when analyzed through a linear model, it is observed that such loads reduce system damping, thereby decreasing stability margins and potentially rendering the system unstable. Additionally, uncertainties in the physical components of the circuit further affect the stability and performance of microgrids. Hence, designing regulators to mitigate oscillations caused by these effects becomes crucial to ensure the proper performance of these systems.In this work, a robust controller is designed to handle uncertainties and attenuate oscillations in the presence of constant power loads. This controller is implemented in a microgrid composed of two cascaded DC-DC buck converters, one of which is modeled as a CPL. The system model is utilized for both stability analysis and robust controller design in state space, where the compensator synthesis is structured in the form of a linear matrix inequality, solved using system optimization tools. The controller’s results are compared with another controller based on pole placement in both linear and nonlinear switched models, within the Matlab/Simulink simulation platform. Transient response and control signals are evaluated graphically and through performance indices under various operating conditions, including load disturbances and system parameter variations.