A comparison of performance indexes in DC-DC converters under different stabilizing state-dependent switching laws

This paper deals with the problem of establishing stabilizing state-dependent switching laws in DC-DC converters operating at continuous conduction mode (CCM) and comparing their performance indexes. Firstly, the nature of the problem is defined, that is, the study of switched affine systems, which may not share a common equilibrium point. The concept of stability is, therefore, broadened. Then, the central theorem is proposed, from which a family of switching laws can be derived, namely the minimum law and the hold state law. Some of these are proved to stabilize the basic DC-DC converters and then, their performances are compared to another law, from a previous work, by simulation, where a great reduction in overshoot is obtained. © 2011 IEEE.

3-D Space Vector PWM implementation for Four-Leg Voltage Source Inverter

The Space Vector PWM implementation and operation for a Four-leg Voltage Source Inverter (VSI) is detailed and discussed in this paper. Although less common, four-leg VSIs are a viable solution for situations where neutral connection is necessary, including Active Power Filter applications. This topology presents advantages regarding the VSI DC link and capacitance, which make it useful for high power devices. Theory, implementation and simulations are also discussed in this paper. © 2011 IEEE.

Delay time detection and accommodation for a networked DC motor control

This paper presents a control method that is effective to reduce the degenerative effects of delay time caused by a treacherous network. In present application a controlled DC motor is part of an inverted pendulum and provides the equilibrium of this system. The control of DC motor is accomplished at the distance through a treacherous network, which causes delay time in the control signal. A predictive technique is used so that it turns the system free of delay. A robust digital sliding mode controller is proposed to control the free-delay system. Due to the random conditions of the network operation, a delay time detection and accommodation strategy is also proposed. A computer simulation is shown to illustrate the design procedures and the effectiveness of the proposed method. © 2011 IEEE.

New integrated Zeta and Cuk inverters intended for standalone and grid-connected applications

This paper presents new inverter topologies based on the integration of a DC to DC Zeta or Cuk converter with a voltage source inverter (VSI). The proposed integration procedure aims to reduce the amount of components, meaning lower volume, weight and costs. In this context, new families of single-phase and three-phase integrated inverters are also presented. Therefore, considering the novelty for Zeta and Cuk integrated inverters structures, the proposed single-phase and three-phase inverters versions are analyzed for grid-tied and stand-alone applications. Furthermore, in order to demonstrate the feasibility of the proposal, the main simulation and experimental results are presented. © 2011 IEEE.

AC-DC three-phase multipulse converter with boost DC-DC stage and constant hysteresis control

This work proposes a new three-phase multipulse rectifier based on the delta autotransformer connection with DC-DC Boost stages and constant hysteresis control which has the objective of providing a reliable DC bus for on-board applications, electric motor drives and similars, always considering power quality issues. Thus, the proposal presents 0.99 power factor, 6% harmonic distortions in the currents from the mains and enhanced magnetic core utilization, which results in low weight and volume for the overall converter. The proposed control technique uses the simple constant hysteresis concept, thus leading to a low-cost but effective and reliable strategy. © 2011 IEEE.

Resonant (P+RES) controller applied to voltage source inverter with minimum DC link capacitor

Voltage source inverters use large electrolytic capacitors in order to decouple the energy between the utility and the load, keeping the DC link voltage constant. Decreasing the capacitance reduces the distortion in the inverter input current but this also affects the load with low-order harmonics and generate disturbances at the input voltage. This paper applies the P+RES controller to solve the challenge of regulating the output current by means of controlling the magnitude of the current space vector, keeping it constant thus rejecting harmonic disturbances that would otherwise propagate to the load. This work presents a discussion of the switching and control strategy. © 2011 IEEE.

Quantification of water in ethanol using a photothermal transparent transducer

Ethanol with added water may be found during the process of assessing its physical and chemical properties. This addition can damage automotive vehicle engines and also may contribute to tax evasion. The present contribution describes a method based on a photothermal transparent transducer to determine the water content in ethanol. A chamber with a window of lithium tantalate coated with a thin layer of indium tin oxide was used, and a 1450-nm laser diode was employed as the excitation source. The results indicated a nearly linear response of the apparatus, as a function of the water content in water/ethanol solutions ranging from 0 to 100 (vol.%). The results for the dependency of the photothermal signal on the laser power and chopping frequency suggested that reliable results can be obtained using laser power and chopping rates above 100 mW and 10 Hz, respectively. The results reported here may be useful in the development of an alternative method that can provide real-time data on the water concentration in ethanol in a rapid, portable and unambiguous way, and that can be easily used in laboratory analyses or in gas stations. © 2013 Elsevier B.V.

Análise e implementação de um algoritmo de busca dispersa para o planejamento da expansão de sistemas de transmissão

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Planejamento da expansão de sistemas de transmissão usando algoritmos tipo dual simplex especializados em uma estrutura branch and bound

Pós-graduação em Engenharia Elétrica - FEIS

Metodologia para o cálculo de harmônicas em conversores de potência no sistema HVDC

Pós-graduação em Engenharia Elétrica - FEIS

Metaheurística GRASP para o problema de planejamento da expansão de sistemas de transmissão de energia elétrica

Pós-graduação em Engenharia Elétrica - FEIS

Desenvolvimento de uma câmara fototérmica com transdutor transparente para monitoramento de água em etanol combustível

Pós-graduação em Engenharia Elétrica - FEIS

Redespacho de reativos como ação corretiva para alívio de sobrecargas em Redes de transmissão

Pós-graduação em Engenharia Elétrica - FEIS

Modelo analítico para linhas de transmissão de energia elétrica: aplicação em linhas trifásicas com plano de simetria vertical

Pós-graduação em Engenharia Elétrica - FEIS

Análise de novos modelos matemáticos para o problema de planejamento da expansão de sistemas de transmissão

Pós-graduação em Engenharia Elétrica - FEIS