Jeferson Vieira Flores

Multiple Resonant Controllers for Uninterruptible Power Supplies—A Systematic Robust Control Design Approach

This paper deals with the synthesis problem of multiple resonant controllers for uninterruptible-power-supply systems in a robust control framework. The controller parameters aiming the tracking of sinusoidal reference signals (with zero steady-state error) and the rejection of harmonic components of the output voltage (when supplying energy to time-varying nonlinear loads) are determined by means of a convex optimization problem subject to a set of linear-matrix-inequality constraints. Results from a 5.0-kVA experimental setup are considered to illustrate and validate the proposed approach.

A framework for the nonlinear control of dual-stage systems

Abstract This paper presents a framework for the nonlinear control of dual-stage actuators (DSA). Motivated by various nonlinear controllers that make use of sector bounded and £ ∞ nonlinearities for the control of saturated linear systems, a methodology for integrating such nonlinear functions in order to improve the performance of DSA is presented. The stability of the closed-loop system is assessed by casting the nonlinearities in a mixed sector-bounded plus quasi-Linear Parameter Varying (LPV) framework, leading to a set of linear matrix inequalities (LMIs) to be satisfied by the controller parameters. Taking advantage of the developed framework, a new £ ∞ function is proposed to avoid the saturation of the secondary actuator. Simulation results illustrate the validity of the proposed framework and its potential for the performance improvement of DSA.

Alternative resonant controller design for Uninterruptible Power Supplies (UPS)

The main objective of this paper is to present an alternative procedure to design resonant controllers for Uninterruptible Power Supplies (UPS). With this aim, a set of equations to determine controller gains is proposed based on the desired output response and the parameters of a class of UPS systems. First, the desired closed-loop poles are determined considering the Linear Matrix Inequalities (LMI) framework. Based on the characteristic polynomial representing the desired closed-loop performance and the plant parameters, algebraic conditions are derived to determine the controller gains for a range of UPS parameters and loads. Simulation and experimental results illustrate the effectiveness of the proposed methodology.

Internal model control of the Zeta Converter for the grid connection of photovoltaic panels

This paper presents the study and application of resonant controllers applied to a Zeta Converter designed to synthesize a rectified sine current compatible with the power grid in order to connect solar photovoltaic (PV) panels to it. Operating in discontinuous conduction mode, the Zeta Converter is connected to a full-bridge inverter so that one semi-cycle of the output current is inverted for every cycle of the power grid voltage. The assembly formed by PV panel and inverter is known as Module-Integrated Inverter (MII). Controller design is performed by the solution of an optimization problem with restrictions in the form of Linear Matrix Inequalities (LMIs) which guarantee the closed-loop system stability and performance. Experimental results of the developed controller, whose objective is reduction of the harmonic content on the inverter output current and synchronism with the power grid, point to the viability of this solution.

Controlador de tempo quase ótimo para sistemas bidimensionais

Este artigo foca no desenvolvimento de um controlador de tempo semi otimo para sistemas de corpo rigido bidimensionais. A abordagem baseia-se na tradicional tecnica de controle Proximate Time-Optimal Servomechanism (PTOS), a qual inicia com uma aproximacao do Time-Optimal Control (TOC) e, em seguida, comuta para um controlador linear Proporcional Derivativo (PD), no instante em que a saida do sistema se aproxima da referencia. Este artigo propoe uma expansao do PTOS, uma lei de controle especifica para sistemas unidimensionais, para ser utilizado em sistemas bidimensionais a fim de realizar trajetorias lineares ponto a ponto.