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About

Nayara Brandão de Freitas received the M.S. and D.Sc. degrees in Power Electronics Engineering, Electrical Engineering, in 2016 and 2020, respectively, from the Federal University of Campina Grande (UFCG), Campina Grande, Brazil. She received a B.S. in Automation and Control Engineering, Electrical Engineering, from UFCG in 2015. As an undergraduate student, she was a member of the Tutorial Education Program of the UFCG Bachelor’s in Electrical Engineering Program from 2010 to 2012. In 2013, she was an exchange student at Purdue University, US, with the sponsorship of the Science without Borders Program. From 2014 to 2015, she received scholarships from the Institutional Scientific Initiation Scholarship Program (PIBIC). Nayara received the Professor Mário Toyotaro Hattori Award, granted to the students with the best academic performance within the UFCG Electrical Engineering and Computer Science departments who graduated in the class of 2015.1. During the M.S. and D.Sc. studies, Nayara was sponsored by the Brazilian National Council for Scientific and Technological Development (CNPq). From December 2018 to November 2019, she was a Visiting Scholar at the Center for Power Electronics Systems, Virginia Tech, US. From April 2020 to May 2021, she was a Postdoctoral Researcher at UFCG. Since June 2021, Nayara has been a Researcher at the Center for Power and Energy Systems, Institute for Systems and Computer Engineering, Technology and Science (INESC TEC), Portugal. Her current research interests include power electronics for Renewable Energy Systems (RESs) integration. She is a member of the Industry Applications Society (IAS) and the Power Electronics Society (PELS) of the Institute of Electrical and Electronics Engineers (IEEE). She graduated from the IEEE Volunteer Leadership Training Program (VoLT) in 2018. She co-founded and was the first chair of the UFCG PELS/IAS Student Branch Chapter from January 2017 to March 2018. She was PELS Student Membership Chair from September 2018 to October 2020. Nayara is currently a member of the PELS Students and Young Professionals Committee and the PELS Women in Engineering (WIE) Committee.

Interest
Topics
Details

Details

  • Name

    Nayara Brandão de Freitas
  • Cluster

    Power and Energy
  • Role

    Assistant Researcher
  • Since

    22nd June 2021
Publications

2021

Grid-Connected Induction Motor Using a Floating DC-Link Converter Under Unbalanced Voltage Sag

Authors
Cunha, MF; Jacobina, CB; de Freitas, NB;

Publication
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS

Abstract
This article proposes a series compensator with unbalanced voltage sag ride-through capability applied to grid-connected induction motors. A conventional three-phase voltage source inverter (VSI) is intended to regulate the motor voltages. The VSI is connected in series with the grid and a three-phase machine with open-ended windings. The proposed system is suitable for applications in which no frequency variation is required, like large pumps or fans. The VSI dc-link voltage operates as a floating capacitor through the energy minimized compensation (EMC) technique, in which there is no dc source or injection transformer. The motor load condition determines the minimum grid voltage positive component (sag severity) to keep EMC operation. Meanwhile, a voltage unbalance may increase the dc-link voltage requirements. A 1.5-hp four-pole induction motor has been used to verify the ride-through capability of the proposed compensator under grid voltage disturbances. A total harmonic distortion (THD) analysis of grid currents demonstrates that the proposed system provides low THD even if no passive filter is used. The operating principle, converter output voltage analysis, pulsewidth modulation technique, control strategy, and components ratings are discussed as well. Simulation and experimental results are presented to demonstrate the feasibility of the system.

2021

Single-Phase Three-Wire Power Converters Based on Two-Level and Three-Level Legs Using a Space-Vector PWM-Based Voltage Balancing

Authors
Gehrke, BS; Jacobina, CB; de Sousa, RPR; da Silva, IRFMP; de Freitas, NB; Correa, MBD;

Publication
IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS

Abstract
This article proposes four converters for interfacing a single dc power source and loads of a single-phase three-wire system. The topologies of the proposed converters are based on two-level (2L) and three-level neutral point clamped (NPC) legs. For regulating the dc-link capacitors of the NPC-based converters, a dc-link voltage-balancing technique is proposed to balance the neutral-point voltage using the space-vector pulsewidth modulation, considering the harmonic distortion of the output voltages and the semiconductor losses from an algorithm that defines the vector sequences to be applied. These characteristics make the proposed converters suitable for applications in microgrid employing dc distributed energy resources or ac power supply by adding ac-dc stage. The proposed converters are compared to a conventional 2 L converter from simulated results for evaluating the semiconductor losses in balanced and unbalanced load scenarios. Experimental results are presented to verify the effectiveness of the proposed voltage-balancing technique and to validate the converters.

2021

Women in IEEE PELS: Learning From the Past, Defining the Future

Authors
Kim, KA; Kegley, LE; Butler, SW; de Freitas, NB; DiMarino, C;

Publication
IEEE POWER ELECTRONICS MAGAZINE

Abstract

2021

Cascaded Transformer Symmetric Single-Phase Multilevel Converters with Two DC Sources

Authors
de Lacerda, RP; Jacobina, CB; de Freitas, NB; Mello, JPRA; Cunha, MF;

Publication
IEEE Transactions on Industry Applications

Abstract

2021

First IEEE PELS Students and Young Professionals Symposium [Society News]

Authors
Brandao de Freitas, N;

Publication
IEEE Power Electronics Magazine

Abstract