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Publications

Publications by Rui Esteves Araujo

2018

Switched Reluctance Machine Modeling through Multilayer Neural Networks

Authors
Mamede, ACF; Camacho, R; Araújo, R;

Publication
Renewable Energy and Power Quality Journal

Abstract

2018

Smart Balancing Control of a Hybrid Energy Storage System based on a Cell-to-Cell Shared Energy Transfer Configuration

Authors
Pinto, C; de Castro, R; Barreras, JV; Araujo, RE; Howey, DA;

Publication
2018 IEEE VEHICLE POWER AND PROPULSION CONFERENCE (VPPC)

Abstract
This work deals with the design of a smart balancing system for e-mobility applications. Low-cost bi-directional DC/DC converters, based on cell-to-cell shared energy transfer configuration, are used to connect battery cells to the balancing bus, which also includes a supercapacitor bank. This system can be seen as a hybrid battery management system (HBMS), since, in addition to traditional BMS features, it also enables hybridization of batteries and supercapacitors. A convex optimization problem is formulated to control the HBMS, focusing on the minimization of energy losses, while considering safety and balancing constraints. Simulation results demonstrate that, in comparison with state-of-the-art BMS solutions, the proposed HBMS reduces energy losses in up to 15%.

2019

Steganography for Indoor Location

Authors
Moutinho, J; Freitas, D; Araujo, RE;

Publication
2019 AES INTERNATIONAL CONFERENCE ON AUDIO FORENSICS

Abstract
This paper presents steganography techniques that were employed to avoid human perception of the added audio signals in an acoustic environment for indoor location purposes. In the context of audio forensics, indoor location can be used in connection with the detection of a crime. The validation of using the acoustic channel for data transmission over an almost imperceptible audio signal enables the possibility of a receiving processing mobile device (such as a smartphone) to localize itself absolutely by receiving and processing such signals from the infrastructure. Some possible applications will be presented demonstrating the utility of this technology. This paper will present the use of almost imperceptible audio signals to successfully transmit hidden information using a spread spectrum data-hiding technique or a music/speech cover signal and the echo hiding technique.

2019

Analysis and design of a speed controller for switched reluctance motor drive

Authors
Pereira M.; Araújo R.E.;

Publication
U.Porto Journal of Engineering

Abstract
This paper presents a speed control of the reluctance machine for electric drive applications with fast dynamic demand. To get high-performance speed control, a cascade control algorithm is developed based on linear control technique. The controller is designed using the Root Locus Methodology and implemented on a numerical simulation platform. The design using Root Locus Methodology proved to be a viable approach and showed that various problems associated with the structural torque ripple of the electric motor can be solved. An important aspect of this work is the role played by model linearization in testing the sensitivity of the controller performance to specific parameter changes. The controller is applied to a simulated non-linear switched reluctance motor model in order to evaluate their performances. Simulation results showed that high-performance control for Switched Reluctance Motor has been achieved.

2019

Influence of Geometric Dimensions on the Performance of Switched Reluctance Machine

Authors
Mamede, ACF; Camacho, JR; Araujo, RE;

Publication
MACHINES

Abstract
In a design of a switched reluctance machine, there are a number of parameters that are chosen empirically inside a certain interval, therefore to find an optimum geometry it is necessary to determine how each parameter acts on the performance of the machine. This work presents a study on the influence of geometric dimensions on the performance of the switched reluctance machine. The analysis is done through finite element simulations based on the variation of one parameter while the others are fixed. Graphical and numerical results of torque and magnetic flux are presented for a 6/4 three-phase machine and an 8/6 four-phase machine. The study presented aims to provide consistent data on which dimensions should be modified for specific applications, and thus to base choices made in the design and optimization stage.

2019

Smart and Hybrid Balancing System: Design, Modeling, and Experimental Demonstration

Authors
de Castro, R; Pinto, C; Barreras, JV; Araujo, RE; Howey, DA;

Publication
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY

Abstract
Performance of series connected batteries is limited by the "weakest link" effect, i.e., the cell or group of cells with the poorest performance in terms of temperature, power, or energy characteristics. To mitigate the "weakest link" effect, this study deals with the design, modeling, and experimental demonstration of a smart and hybrid balancing system (SHBS). A cell-to-cell shared energy transfer configuration is proposed, including a supercapacitor bank in the balancing bus, thus enabling hybridization. Energy is transferred from each battery module connected in series to the balancing bus, and vice-versa, by means of low-cost bi-directional dc-dc converters. The current setpoints of the converters are obtained by means of a smart balancing control strategy, implemented using convex optimization. The strategy is called "smart" because it pursues goals beyond the conventional state-of-charge equalization, including temperature and power capability equalization, and minimization of energy losses. Simulations show that the proposed SHBS is able to achieve all these goals effectively in an e-mobility application and are also used to assess the impact of different hybridization ratios and cooling conditions. Finally, an experimental setup is developed to demonstrate the feasibility of the SHBS.

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