Resumo em Inglês:

ABSTRACT This paper explores the essential role of power electronics in modern electrical engineering and emphasizes the need for practical, hands-on learning experiences. By utilizing an easily-accessible, modular educational platform consisting of the DSP TI C2000 LAUNCHXL-F280049C and the BOOSTXL-3PHGANINV three-phase inverter module from Texas Instruments, students can bridge the gap between theoretical knowledge and practical application. Detailed descriptions of the hardware, along with case studies on a bidirectional boost converter and a three-phase inverter, illustrate the effectiveness of this approach. The findings show that integrating experiential learning methodologies significantly enhances student engagement and comprehension. The platform enables students to simulate, prototype, and experimentally verify their designs, promoting a deeper understanding of power electronics principles. The paper concludes by highlighting the potential for expanding this educational framework to include additional modules and applications, thereby preparing students more effectively for the evolving demands of the power electronics industry.

Resumo em Português:

RESUMO A recente onda de eletrificação dos meios de transporte tem exigido a aplicação de máquinas elétrics com acionamentos mais sofisticados com rápida resposta din amica e robustez. Nesse contexto, os motores de indução (MI) ainda são uma boa solução, especialmente pela sua simplicidade construtiva. Entre as estrategias de controle mais recentes para essas máquinas, destaca-se o controle preditivo. Este artigo compara tres métodos de controle preditivo de corrente: o Finite Control Set Classico (PCC, do ingles Predictive Current Control), o Robusto Deadbeat (RPCC-Deadbeat) e o Robusto utilizando ação integral em tempo discreto (RPCC-DTIA). Estes controladores sao promissores por sua resposta din˜ amicaˆ rapida, flexibilidade e inclus ao de não linearidades. Resultados obtidos em bancada experimental comparam o desempenho do PCC, RPCC-Deadbeat e RPCC-DTIA. As analises demonstram as diferenças entre as estrategias por meio de respostas din amicas e de regime, avaliando o comportamento dos controladores frente a variaçoes de parâmetros da máquina, como resistência e indutância.

Resumo em Inglês:

ABSTRACT The recent wave of transportation electrification has required the application of electric machines with more sophisticated drives with fast dynamic response and robustness. In this context, induction motors are still a good solution, especially due to their constructive simplicity. Predictive control stands out among the most recent control strategies for these machines. This article compares three predictive current control methods: Finite Control Set (PCC), Robust Deadbeat (RPCC-Deadbeat), and Robust using Discrete-Time Integral Action (RPCC-DTIA). These controllers are promising due to their fast dynamic response, flexibility, and inclusion of nonlinearities. Experimental results performed in Simulink compare the performance of PCC, RPCC-deadbeat, and RPCC-DTIA. The analyses demonstrate the differences between the strategies through dynamic and steady-state responses, evaluating the behavior of the controllers when faced with variations in machine parameters, such as resistance and inductance.

Resumo em Inglês:

ABSTRACT The maintenance of photovoltaic plants is crucial to ensure their proper performance, longevity, and efficiency, while also enhancing the return on investment and contributing to sustainable energy production. In such context, this paper proposes a methodology to characterize the main issues in photovoltaic plants, based on the analysis of the proposed inverter output power curve. Through power curve analysis, the most common anomalies and faults encountered in inverters are identified, providing a valuable tool for the early detection of operational issues. Additionally, power curve analysis allows a comparison between projected and actual values of generated energy, offering an index of system energy losses. Lastly, an economic analysis is presented, ranking inverters based on the magnitude of their energy losses, from highest to lowest. This analysis provides important insights for prioritizing maintenance actions and allocating resources to enhance generation returns.

Resumo em Português:

RESUMO Topologias de conversores integrados de único estágio têm sido amplamente empregadas em aplicações que requerem a conversão CC/CA. Diante disso, este trabalho apresenta uma nova topologia de inversor integrado obtida pela combinação das topologias dos conversores Zeta e Ćuk, denominado Inversor Híbrido Zeta-Ćuk (IHZC). A topologia do IHZC apresenta as seguintes vantagens: i) emprego de quatro interruptores de potência; ii) aproveitamento total da tensão de entrada; e iii) elevado rendimento. O IHZC é projetado para operar no modo de condução descontínua em aplicações monofásicas autônomas em CA, onde a tensão de saída é controlada e regulada por meio de um controlador proporcional-integral multi-ressonante. A viabilidade e operação da topologia IHZC são avaliadas e comprovadas através de resultados experimentais, os quais demonstram que a estrutura é capaz de fornecer tensão CA de saída com baixa distorção harmônica e operar com elevado rendimento.

Resumo em Inglês:

ABSTRACT Multilevel resonant converter topologies have been addressed to increase the power density and efficiency of step-down intermediate conversion stages, for low-voltage (LV) systems, due to the higher current demand, in addition to its inherent benefit of soft-switching capability and fixed static-gain ratio, while operating at, or above, resonance. This work proposes an extension for the multilevel Resonant Flying Capacitor Converter (ML-RFLCC), by demonstrating the potential soft-switching and voltage regulation capabilities of a 1:3 RFLCC while operating under and at the resonance. Due to the increased number of state variables, it presents a comprehensive state diagram, and normalization framework, to demonstrate the operating principle, and dependencies, of the different set of LC resonant tanks. In order to achieve such an operation, this work proposes an operating condition coefficient Λ to derive a design methodology. To validate the proposed operation condition, a 400V 500W GaN-based 1:3 RFLCC is presented, illustrating the theoretical correlation and non-idealities while operating under resonance.

Resumo em Inglês:

ABSTRACT This study evaluates IGBT modules with a focus on efficiently measuring their thermal impedance, a critical factor in reliability assessments. The research employs the Thermo Electric Sensitive Parameter method to measure the Virtual Junction Temperature and obtain the Thermal Impedance curve. These experimental results are compared with datasheet values, using power modules without a baseplate. Two methodologies, dynamic and static, are utilized, both demonstrating consistent performance in evaluating thermal characteristics. The study also addresses the importance of accounting for nonlinearity in thermal conductance due to temperature dependency, which is essential for accurate thermal characterization. Additionally, it explores the potential for measuring the Thermal Impedance between Junction and Case in power modules without a baseplate, offering a comprehensive understanding of thermal performance.

Resumo em Português:

RESUMO Este artigo apresenta uma metodologia de identificação de falhas de circuito aberto aplicada ao conversor Cascata de Pontes Completa (Cascaded H-Bridge - CHB) que não depende da estratégia de modulação adotada. A técnica de identificação de falhas proposta neste artigo utiliza os sinais que são usualmente medidos para o controle deste conversor, tornando-o um método de fácil adaptação, podendo ser considerando de baixo custo de implementação. A identificação do evento de falha de circuito aberto de um dos interruptores é feita através da leitura do valor médio da tensão de saída. Este valor médio é tratado através de um filtro média móvel e, a partir dele, é possível determinar a condição de existência de falha do conversor. Com esta condição de falha ativa, são executados dois procedimentos principais, uma rotina de testes e uma estratégia de identificação e correção do módulo danificado. O método é validado experimentalmente utilizando um conversor CHB monofásico com quatro módulos, com modulação PDPWM. O estudo se originou da análise de falhas em módulos pontes completa quando operando sobre modulações multiníveis, também apresentado nesse artigo.

Resumo em Português:

RESUMO Este artigo propõe uma abordagem de controle coordenado utilizando conversores eletrônicos de velocidade variável (AFE-ASDs), para o gerenciamento avançado de potência em plataformas marítimas de petróleo, do tipo FPSO (Floating Production Storage and Offloading). A metodologia de controle coordenado é fundamentada na Teoria de Potência Conservativa e visa mitigar a potência reativa, as distorções harmônicas e desbalanços, fazendo uso da disponibilidade de potência dos AFE-ASDs distribuídos. Simulações computacionais da abordagem proposta considerando o modelo real de sistema elétrico de uma FPSO demonstram uma redução de 10,16% na potência dos geradores a gás, em condições de estado estacionário. Durante a partida direta de motores, a coordenação dos AFE-ASDs também possibilitou que a variação de tensão diminuísse de 14,45% para 2,64%. Além disso, uma redução significativa na distorção harmônica foi alcançada pela mitigação de correntes de distorção, com o DHTi diminuindo de 5,42% para 1,39% e DHTv de 3,89% para 0,98%.

Resumo em Inglês:

ABSTRACT This paper proposes a coordinated control approach using Active Front End Adjustable Speed Drives (AFE-ASDs) for advanced power management in Floating Production, Storage, and Offloading (FPSO) oil platforms. The coordinated control methodology is formulated based on the Conservative Power Theory and aims to mitigate reactive power, harmonic distortion, and unbalance by leveraging the power availability of distributed AFE-ASDs. Computational simulations considering a FPSO power system model, derived from equipment data and operational reports, demonstrate a 10.16% power reduction in gas turbine generators under steady-state conditions upon the implementation of the proposed control approach. During direct motor startups, voltage deviation decreased from 14.45% to 2.64% due to the coordinated operation of the AFE-ASDs. Besides, a significant reduction in harmonic distortion was achieved, with THDi decreasing from 5.42% to 1.39% and THDv from 3.89% to 0.98%.

Resumo em Inglês:

ABSTRACT This paper presents a design guide for applying an integral convex control set modelbased predictive control (CCS-MPC) in a surface permanent magnet synchronous machine (SPMSM). The proposed CCS-MPC has an intrinsic integral action that eliminates the need of an external disturbance estimator for disturbance rejection. In the control design, this work presents a relation between the openloop cost function weighting factor and the closed-loop bandwidth factor, which could be used to improve the controller design. Several tests are performed in the hardware-in-the-loop experimental, as sinusoidal and step reference tracking. Experimental frequency responses are also provided.

Resumo em Português:

RESUMO Traçadores de curvas características de modulos fotovoltaicos são uma importante ferramenta para monitoramento e avaliação do desempenho de usinas solares. Entretanto, dimensionar o tempo de aquisição de dados e uma tarefa complexa e um valor inadequado pode resultar em curvas caracter ísticas incompletas ou com sobreamostragem na região de tensão de circuito aberto (Voc ). O objetivo desta metodologia e o dimensionamento correto do tempo de aquisição dos dados. Assim, um fator de ajuste, calculado através de um ciclo de carga do capacitor, e proposto. Este trabalho apresenta uma metodologia de aquisição de dados com ajuste dinâmico, usando um protótipo de traçador de curvas características de modulos fotovoltaicos baseado em carga capacitiva. Os resultados mostram curvas caracter ísticas com uma distribuição mais uniforme dos pontos amostrados, permitindo maior resolução no ponto de máxima potencia (Pmax ).

Resumo em Inglês:

ABSTRACT Characteristic curve tracers for photovoltaic modules are a critical tool for monitoring and evaluating solar power plant performance. However, dimensioning the data acquisition time is a complex task, and an inappropriate value can result in incomplete characteristic curves or oversampling in the opencircuit voltage (Voc ) region. The objective of this methodology is to correctly dimension data acquisition time. Therefore, an adjustment factor, calculated through a capacitor charging cycle, is proposed. This work presents a data acquisition methodology with dynamic adjustment, using a characteristic curve tracer prototype for photovoltaic modules based on capacitive charging. The results demonstrate characteristic curves with a more uniform distribution of sampled points, enabling higher resolution at the maximum power point (Pmax ).

Resumo em Inglês:

ABSTRACT This paper presents an isolated regenerative active-clamped circuit designed for the current-fed half-bridge (IRACCFHB) converter. Its primary function is to reduce high voltage spikes across the main switches caused by energy stored in the leakage inductance of the power transformer using a clamping capacitor. This recovered energy is delivered efficiently to the load, maintaining the converter’s high efficiency and voltage ratio. The proposed auxiliary circuit employs a single active switch with the same ground reference as the main switches, eliminating the need for an isolated gate driver. The converter achieves zero voltage switching (ZVS) during the turn-off of the main switches and zero current switching (ZCS) during the turn-on of the auxiliary switch. Energy recovery to the load is accomplished without compromising galvanic isolation due to employing a coupled inductor in the auxiliary circuit. To validate the proposed analysis and design, a 350 W prototype was implemented.

Resumo em Inglês:

ABSTRACT This paper proposes a cascade/ladder switched capacitor converter integrated with an interleaved synchronous buck converter to provide a 48 V to 1 V conversion for data center applications. The switched capacitor stage decreases the input voltage from 48 V to 3 V (a reduction of 16 times), with low voltage stress on the input switches and intermediate voltage levels that can be used as voltage sources. The interleaved buck stage provides voltage and current control and is connected in cascade with the switched capacitor stage to reduce the voltage from 3 V to 1 V (a reduction of 3 times). Furthermore, a switching frequency optimization is proposed for the switched-capacitor converter to maximize efficiency. The proposed solution was experimentally validated in a two-stage 30 W prototype: the first stage is the proposed cascade/ladder switched capacitor topology (48 V to 3 V) with unregulated conversion, which provides a maximum efficiency of 91,6%, and the second stage is the buck converters (3 V to 1 V) with regulated conversion.

Resumo em Inglês:

ABSTRACT This paper proposes a new fully integrated Boost and Buck converter. The topology results from integrating the Boost as the power factor correction (PFC) stage and the Buck as power control (PC) stage. Besides this, the paper presents a methodology for designing the PFC stage inductor based on the inductance ratio between the PFC and PC stage inductances. In this work, the methodology analysis is carried out to enhance the converter power density using magnetics integration. Magnetic circuits and finite elements simulations compare the standalone and the integrated magnetics designs. Finally, the methodology is validated for the proposed fully integrated topology by implementing an 180 W LED driver prototype, which works properly for the grid voltage range (180-250 Vrms ) and ensures full DCM operation between 10 and 100% of the LED load power. The experimental results show that the proposed topology fulfills the recommendation IEEE 1789-2015 and the standard IEC 61000-3-2 (Class C) in the grid range. The peak efficiency is 93.5% at 180 Vrms . The integrated magnetic enables a volume reduction of 20% compared to the standalone magnetics. The converter component count is significantly reduced compared to LED drivers found in the literature for street-lighting applications.

Resumo em Inglês:

ABSTRACT This paper presents a control strategy for grid-forming inverters, utilizing a cascaded dual-control scheme that integrates current and voltage controllers, along with an outer loop for regulating the injected active and reactive power. The proposed approach enhances system performance by addressing key challenges faced by grid-forming inverters. One of the highlights of this strategy is the improved disturbance rejection capability of the current controller, achieved through capacitor voltage decoupling. This modification effectively reduces the impact of disturbances on system performance. Additionally, the voltage controller incorporates the concept of disturbance input decoupling, which further improves the inverter’s dynamic response under varying operating conditions. Notably, the inclusion of disturbance input decoupling enhances the loop gain of the voltage controller in the low-frequency range, leading to superior performance of the inverter. Experimental results validate the efficacy of the proposed control strategy in managing real-word scenarios such as voltage sags, load changes and variations in power references. These findings highlight the robustness of the proposed methodology, demonstrating its potential for enhancing the operation of grid-forming inverters in modern power systems.

Resumo em Português:

RESUMO O projeto de filtros de interferência eletromagnética consiste em especificar a topologia e os elementos de uma rede elétrica cuja função é atenuar sinais interferentes. Esse trabalho apresenta uma metodologia iterativa de projeto de filtros de EMI para fontes chaveadas baseada no teorema do elemento sequencial e no conceito de efeito dominante em compatibilidade eletromagnética. Para tanto, estudaram-se as emissões conduzidas de modo comum, de modo diferencial e de modo misto, bem como as não idealidades dos elementos e a característica da impedância de entrada das fontes chaveadas. A partir de ensaios com três protótipos de produtos comerciais e o arcabouço de conhecimento adquirido, foi proposta essa abordagem de projeto. Nos testes práticos, foram perceptíveis o efeito da ressonância do filtro de EMI e o efeito da impedância de entrada de modo misto do conversor sobre a atenuação do elemento série do filtro. Isso serviu como uma diretiva para definição de qual componente incluir ou aumentar o valor no filtro de EMI. Dessa forma, os requisitos mais restritivos das normas foram atendidos com poucas iterações e menor número de componentes que os filtros originais, evidenciando que os conceitos tomados como referência mostram-se válidos e oportunos.

Resumo em Inglês:

ABSTRACT Electromagnetic interference filter design specifies circuit topology and elements, inductors, and capacitors of an electrical network whose purpose is to reduce interferential signals. This work presents an iterative methodology of EMI filter design for switched power supplies based on the sequential element theorem and the concept of the dominant effect in electromagnetic compatibility. This design methodology was proposed based on experiments with three commercial off-the-shelf power supplies and knowledge about common, differential, and mixed-mode emissions, as well as the non-idealities of the elements and the power supply's input impedance characteristics. In practical tests, the effect of the EMI filter resonance and the power supply's mixed-mode input impedance was observed, which served as a guideline for determining which component should be included or whether its value should be increased in the EMI filter structure. The most restrictive requirements were met with a few iterations and fewer components than the original filters, demonstrating that the concepts used as a reference are valid and valuable.

Resumo em Inglês:

ABSTRACT Power electronic systems include many fragile elements, with power devices being the most prone to failure. Cycle counting algorithms are essential to evaluate power devices degradation and system reliability. Among the available options, the rainflow algorithm is the most widely used. Since the rainflow algorithm was originally designed for fatigue analysis, it faces challenges when applied to power devices. Specifically, the conventional rainflow algorithm cannot compute the effective heating time and the time-dependent equivalent mean temperature of the thermal cycles. Additionally, it counts cooling half-cycles, which contradicts the basis of lifetime models, as these models rely on data associated with heating temperature gradients. To address these limitations, this work introduces a modified rainflow algorithm for cycle counting in the lifetime estimation of power devices. This methodology enhances the conventional rainflow by enabling the calculation of effective heating time and mean temperature while also filtering out cooling half-cycles. The results demonstrate that the modified rainflow algorithm significantly affects the lifetime predictions for all critical joints in an IGBT module, regardless of the mission profile. Across all case studies, the utilization of the modified rainflow algorithm resulted in a damage reduction exceeding 53%.

Resumo em Inglês:

ABSTRACT Public transport vehicles based on electric vehicles are suitable for regular extreme fast charging (R-XFC) with supercapacitors as energy storage. Quick recharges cause power quality problems such as high harmonic injection. In this sense, grid-connected converter solutions must address this issue. The main objective of this paper is to present a solution for R-XFC stations with the Zero Harmonic Distortion (ZHD) Converter. The ZHD converter features elements consolidated in the industry and it does not need capacitive filters in the point of common coupling (PCC) with the grid, presenting sinusoidal currents with low harmonic content for regular extreme fast charging (R-XFC) stations. Hardware-in-the- loop (HIL) simulation results of an extreme fast recharge showed a total demand distortion (TDD) of 0.54%, and experimental results of a 280 kVA prototype had a TDD of 2.29%.

Resumo em Inglês:

ABSTRACT Grid-connected inverters must be synchronized with the electrical grid to ensure stability and efficiency. However, abrupt grid distortions and harmonic components can degrade the controller’s performance. This paper proposes a sliding mode controller combined with a PI controller for current control in a single-phase grid-connected inverter to enhance Total Harmonic Distortion performance. The primary contribution of this work is the development of a nonlinear controller with a constant switching frequency, addressing the common chattering problem in sliding mode controllers while maintaining adequate performance under distorted voltage conditions using a Phase-Locked Loop. The controller’s performance was evaluated through laboratory experiments under normal and distorted grid conditions, and the results were compared with a repetitive controller, demonstrating its effectiveness in suppressing harmonics in regular operation and under distorted grid voltage conditions.

Resumo em Inglês:

ABSTRACT Semiconductor switches in high-power density inverters face significant challenges related to temperature rise in their junctions, which can lead to operational failures. The design and analysis of liquid-cooled heat sinks for these inverters are complex due to their multiphysics nature, particularly under dynamic loads typical of power electronics applications. This paper presents a comprehensive methodology for the design, analysis, and evaluation of liquid-cooled heat sinks in high-power density inverters, integrating computational fluid dynamics (CFD), lumped parameter modeling, and experimental validation. The CFD method is used to determine lumped parameters, which are then incorporated into a PLECs model to simulate the thermal dynamics of semiconductor devices. Power losses calculated in PLECs are used as a reference for experimental validation, where an electronic load emulates the heat dissipation of a 30 kW traction inverter with 99% efficiency. Two liquid-cooled heat sink geometries—machined channels and a U-shaped serpentine design—are analyzed under various operational scenarios, including normal operation and failure modes in the cooling system. The results illustrate the efficacy of the proposed methodology in evaluating thermal exchange and the impact of cooling system failures on power traction inverters. This work provides a streamlined approach for designing and testing liquid-cooled heat sinks, offering valuable insights for improving thermal management in high-power density inverters.

Resumo em Inglês:

ABSTRACT This paper presents a single-phase to three-phase AC-DC-AC step-down converter with a symmetrical DC-link voltage ratio. The proposed converter architecture is well-suited for rural distribution grid applications, where a high-voltage single-phase grid is required to transmit energy over long distances while minimizing conduction losses. The converter consists of two cascaded H-bridge converters connected via transformers and two three-phase inverters supplying an open-end winding induction motor (OEWIM). The level-shifted pulse-width modulation (LSPWM) strategy is employed to synthesize the converter voltages. A proportional-integral (PI) controller regulates the overall DC-link voltages, while a hysteresis controller maintains the balance of the individual DC-link voltages. Additionally, a resonant PI controller ensures a sinusoidal grid current, and a Phase-Locked Loop (PLL) is used to achieve a high power factor in the grid. Compared to a conventional two-level leg topology, the proposed configuration reduces harmonic distortion and semiconductor power losses while ensuring a high power factor. Simulation and experimental results validate the effectiveness of the PWM and control strategies.

Resumo em Português:

RESUMO Este artigo apresenta o estudo de duas topologias de conversores CC-CC não isolados com elevado ganho estático, baseadas na associação e na integração dos conversores Boost modificado e SEPIC. A topologia associada possui dois interruptores controlados, enquanto a integrada emprega apenas um. Com a integração, obtém-se a célula de comutação conhecida como R2 P2. Os conversores propostos são capazes de alcançar ganhos de tensão elevados (> 8), sendo ideais para aplicações que demandam poucos componentes e uma conexão comum entre entrada e saída, o que simplifica o circuito de controle e comando. O artigo apresenta os detalhes da derivação das topologias e o princípio de operação, incluindo as etapas e principais formas de onda, além da análise comparativa com conversores semelhantes, previamente propostos na literatura. Para validar as análises, dois protótipos com potência nominal de 200 W, projetados para operar com tensão de entrada de 26 V e tensão de saída de 260 V são apresentados. Ambos operam com frequência de comutação de 50 kHz, atingindo rendimentos de 93,4 % para o conversor associado e 89,2 % para o conversor integrado em potência nominal.

Resumo em Inglês:

ABSTRACT This paper presents a study of two non-isolated DC-DC converter topologies with high static gain, based on the association and integration of modified Boost and SEPIC converters. The associated topology uses two controlled switches, while the integrated one employs only one. When performing the integration, the switching cell known as R2 P2 is obtained. The proposed converters achieve high voltage gains (>8), making them suitable for applications where a reduced number of components is desirable, common connection between input and output, simplifying the control and command circuit. The paper presents the details of the derivation of the topologies and the operating principle including the topological stages and main waveforms, in addition to the comparative analysis with similar converters previously proposed in the literature. To validate the analyses, two prototypes with a nominal power of 200 W, dimensioned to operate with an input voltage of 26 V and an output voltage of 260 V are presented. The converters operate at a switching frequency of 50 kHz, with an efficiency of 93.4 % for the associated converter and 89.2 % for the integrated converter at rated power.

Resumo em Português:

RESUMO Este artigo apresenta o projeto de um conversor ANPC (Active Neutral Point Clamped) de 5 níveis de tensão utilizando uma Célula de Comutação Multiestado (MSSC), operando como inversor. O inversor é associado a três opções de filtros indutivos na saída: um indutor convencional, um conjunto de indutores intercalados e um conjunto de indutores acoplados. Os parâmetros avaliados para estes filtros incluem massa, volume, perdas, elevação de temperatura e eficiência quando combinados com o inversor. As principais características do conversor ANPC-5L-MSSC incluem fluxo bidirecional de potência, baixa distorção harmônica de tensão, alto fator de potência, melhor distribuição de perdas em comparação com a topologia NPC convencional, além de massa e volume minimizados dos componentes passivos, possibilitados pela célula MSSC, que aumenta a frequência efetiva no filtro de saída e, consequentemente, reduz o tamanho dos componentes magnéticos. São demonstradas as etapas de funcionamento do inversor, bem como o dimensionamento dos semicondutores de potência, do autotransformador e dos indutores e capacitores utilizados no filtro. A validação dos cálculos é realizada por meio de comparação com resultados obtidos via simulação numérica. Também são apresentados resultados experimentais obtidos em laboratório, a partir de um protótipo de 1,5 kW.

Resumo em Inglês:

ABSTRACT This paper presents the design of a 5-level Active Neutral Point Clamped (ANPC) converter employing a Multi-State Switching Cell (MSSC), operating as an inverter. The inverter is coupled with three inductive output filter options: a conventional inductor, a set of interleaved inductors, and a set of coupled inductors. The evaluated parameters for these filters include mass, volume, losses, temperature rise, and efficiency when integrated with the inverter. The key features of the ANPC-5L-MSSC converter include bidirectional power flow, low total harmonic distortion of voltage, high power factor, improved loss distribution compared to the conventional NPC topology, and minimized mass and volume of passive components, enabled by the MSSC, which increases the effective output filter frequency and consequently reduces the size of magnetic components. The operational stages of the inverter are demonstrated, along with the sizing of power semiconductors, the autotransformer, and the inductors and capacitors used in the filter. The calculations are validated through comparison with results obtained from numerical simulations. Experimental results from a 1.5 kW laboratory prototype are also presented.

Resumo em Português:

RESUMO O presente trabalho busca apresentar pontos críticos existentes no desenvolvimento de protótipos Double Pulse Test (DPT) para caracterização de interruptores de GaN. O estado da arte é abordado com foco na exposição dos tipos do interruptor de GaN e suas características físicas. É explicado o funcionamento do circuito DPT e a forma como ele é utilizado para os testes do interruptor. O layout da primeira versão do protótipo é desenvolvido e os componentes são selecionados visando minimizar elementos parasitas. A partir dos resultados do primeiro protótipo, um segundo circuito DPT mais compacto é desenvolvido para reduzir indutâncias das trilhas e quantidade de componentes. Essas melhorias impactam no sinal de sobretensão e oscilações do interruptor de GaN sob teste. Uma terceira versão, mais compacta do circuito DPT é desenvolvida em configuração Meia Ponte, substituindo o diodo de roda livre de SiC por um interruptor de GaN, com as mesmas características do dispositivo sob teste, para comparação com os protótipos anteriores. Detalhes experimentais dos três protótipos são apresentados. É evidenciado o impacto nas transições turn-off e turn-on para os níveis de tensão de 200 V e corrente de 10 A, bem como o tempo de transição durante as comutações para as três implementações de circuito DPT, com correntes de 1 a 10 A e tensões de 100 V, 200 V e 275 V. Também é detalhado o modo de condução reversa do protótipo DPT Meia Ponte para 10 A e 100 V.

Resumo em Inglês:

ABSTRACT The present work aims to highlight critical points in the development of Double Pulse Test (DPT) prototypes for characterizing GaN switches. The state of the art is discussed with a focus on the types of GaN switches and their physical characteristics. The operation of the DPT circuit and its use in testing the switches is explained. The layout of the first prototype version is developed, and components are selected to minimize parasitic elements. Based on the results of the first prototype, a more compact second DPT circuit is developed to reduce pcb stray inductances and the number of components. These improvements impact the overvoltage signal and oscillations of the GaN switch under test. A third, more compact version of the DPT circuit is developed in a Half-Bridge configuration, replacing the SiC freewheeling diode with a GaN switch with the same characteristics as the device under test, for comparison with the previous prototypes. Experimental details of the three prototypes are presented. The impact on turn-off and turn-on transitions for voltage levels of 200 V and current of 10 A is highlighted, as well as the transition time during switching for the three DPT circuit implementations, with currents from 1 to 10 A and voltages of 100 V, 200 V and 275 V. The reverse conduction mode of the Half-Bridge DPT prototype for 10 A and 100 V is also detailed.

Resumo em Inglês:

ABSTRACT This paper introduces the exact solution of the Class-E WPT resonant inverter. Dominantly, the DC-AC inverters for WPT systems are analyzed by assuming a sinusoid waveform for the output variables. However, by allowing waveform light distortions, the magnetic element values can be reduced; which is provided by the proposed method. It is shown that the circuit waveforms are composed of sine, cosine and exponential terms. The obtained solutions are used to design a 500 kHz Class-E WPT resonant inverter which operates with ZVS. The design is experimentally verified and 74 % efficiency with 9.7 W output power is achieved.

Resumo em Português:

RESUMO A circulação de conteúdo harmônico é um fenômeno presente nas redes de distribuição de energia elétrica e a atribuição de responsabilidade é compartilhada entre o consumidor e a concessionária. Este artigo apresenta um método de cálculo das Reponsabilidades por Conteúdo Harmônico em redes monofásicas, através da dedução do “Fator de Geração de Harmônicos” e do “Fator de Consumo de Harmônicos” utilizando-se da Teoria de Potências Conservativas. O trabalho apresenta o equacionamento completo destes dois fatores que são obtidos a partir da decomposição do sinal da corrente em suas componentes ortogonais, obtendo-se assim, uma metodologia para o cálculo dos fatores e atribuição de percentuais de responsabilidade em relação ao conteúdo harmônico de uma carga conectada à rede elétrica entre a distribuidora de energia e o consumidor. Resultados de simulação e experimentais são apresentados validando as equações obtidas.

Resumo em Inglês:

ABSTRACT The circulation of harmonic content is a phenomenon present in electricity distribution networks and the assignment of responsibility is shared between the consumer and the utility company. This paper presents a method for calculating the responsibilities for harmonic content in single-phase networks, through the deduction of the “Harmonic Generation Factor” and the “Harmonic Consumption Factor” using the Conservative Power Theory. The work presents the complete equation of these two factors that are obtained from the decomposition of the current signal into its orthogonal components, thus obtaining a methodology for calculating the factors and assigning percentages of responsibility in relation to the harmonic content of a load connected to the electricity grid between the energy distributor and the consumer. Simulation and experimental results are presented validating the equations obtained.

Resumo em Português:

RESUMO O presente trabalho aplica o princípio da estabilidade de Lyapunov para o controle preditivo de corrente por conjunto de estados finitos para motores de indução monofásicos. A fim de alcançar a estabilização exponencial do sistema, a função custo é desenvolvida de forma a minimizar o erro, levando em consideração o vetor de tensão utilizado pelo conversor de potência e seu valor projetado. Para garantir a estabilidade em malha fechada do sistema, as entradas dos vetores de tensão do estator são calculadas utilizando-se o método de Lyapunov aplicado em sistemas de tempo discreto. Para avaliar a eficácia da estratégia de controle foram realizados testes em bancada experimental.

Resumo em Inglês:

ABSTRACT The current study applies the Lyapunov stability principle to the predictive current control approach for single-phase induction motors finite control set type. The cost function is designed to minimize the error by taking into account the voltage vector used by the power electronic converter and its expected value in order to ensure exponential system stabilization. The stator voltage vector control inputs are created using a Lyapunov function technique, which is implemented in discrete-time systems, to ensure the system’s closed-loop stability. Bench tests have been carried out to evaluate the effectiveness of the proposed control approach.

Resumo em Português:

RESUMO Neste artigo é proposto um novo conversor híbrido monofásico que integra o processamento de energia solar fotovoltaica com um sistema de armazenamento em banco de baterias para o suprimento de cargas em corrente alternada. A topologia proposta apresenta um número reduzido de chaves semicondutoras em comparação com estruturas convencionais empregadas em sistemas fotovoltaicos. O princípio de operação, o projeto dos dispositivos e a modelagem dinâmica são descritos em detalhes. Além disso, uma estratégia de modulação é apresentada para gerar os sinais de acionamento do conversor. Adicionalmente, propõe-se um sistema de controle capaz de garantir a operação desacoplada entre as três portas do conversor. Por fim, resultados de simulação e experimentais são apresentados para validar e verificar a praticabilidade do conversor proposto.

Resumo em Inglês:

ABSTRACT This paper proposes a new hybrid single-phase converter that integrates photovoltaic solar energy processing with a battery storage system to supply alternating current loads. The proposed topology employs a reduced number of semiconductor switches compared to conventional structures commonly used in photovoltaic systems. The operating principle, component design, and dynamic modeling are described in detail. A modulation strategy is also introduced to generate the converter’s switching signals. Furthermore, a control system is developed to ensure decoupled operation among the converter’s three ports. Simulation and experimental results are presented to validate the effectiveness and feasibility of the proposed converter.

Resumo em Português:

RESUMO A norma IEC 60034-2-3 tem como objetivo definir os métodos de ensaios para determinar as perdas totais das máquinas elétricas, incluindo as perdas adicionais devido às altas frequências oriundas da alimentação por inversores de frequência. As perdas devido às altas frequências são apresentadas de maneira adicional às perdas em alimentação senoidal, conforme determinado pelo método normalizado pela IEC 60034-2-1. E, segundo a norma, as perdas harmônicas são constantes em toda faixa de operação do motor. Este artigo faz uma revisão da norma IEC 60034-2-3 e apresenta os resultados de uma série de experimentos para avaliar o comportamento das perdas harmônicas em relação aos setes pontos de operação propostos pela norma, determina o mapa de rendimento para as condições de alimentação não-senoidal, conforme instruído pela norma, e compara esses resultados com aqueles obtidos para o motor com alimentação senoidal.

Resumo em Inglês:

ABSTRACT The IEC 60034-2-3 standard aims to define test methods to determine the total losses of electrical machines, including the additional losses due to high frequencies from the power supply by frequency inverters. Losses due to high frequencies are presented in addition to losses in sinusoidal supply, as determined by the method standardized by IEC 60034-2-1. And, according to the regulations, harmonic losses are constant throughout the motor's operating range. This article reviews the IEC 60034-2-3 standard and presents the results of a series of experiments to evaluate the behavior of harmonic losses in relation to the seven operating points proposed by the standard, determines the yield map for non-sinusoidal power supply conditions, as instructed by the standard, and compares these results with those obtained for the motor with sinusoidal supply.

Resumo em Inglês:

ABSTRACT Cryogenic power electronics applications, commonly referred to as cryo-converters, offer key advantages over conventional ambient-temperature systems, including higher power density and improved efficiency. This paper presents the experimental analysis of a prototype cryogenic boost converter (cryoboost) operating in continuous conduction mode (CCM), under both room-temperature and cryogenic conditions. The study focuses on the voltage gain behavior. Two different inductors were tested and compared: an air-core copper coil and a high-temperature superconducting (HTS) aircore inductor (BSCCO pancake coil, 4 mm tape). Experimental results demonstrate that the HTS inductor operating at cryogenic temperatures significantly enhances the voltage gain compared to the copper inductor at room temperature. These findings suggest that HTS-based inductors are a promising alternative for high-gain DC-DC converter applications in cryogenic environments.

Resumo em Inglês:

ABSTRACT The adequate choice of excitation parameters is detrimental to the high performance operation of switched reluctance generators. Such task, however, is a complex problem which lacks solutions with simple analytical formulations. In this context, this paper presents a performance optimization procedure for switched reluctance generators operating in the current controlled region, below base speed. The proposal allows optimal firing angles to be determined based on the particle swarm optimization algorithm. A cost function is designed as a means to ensure performance with a compromise between reduced torque ripple and increased energy efficiency. A comparison with a traditional exhaustive search algorithm is provided, highlighting the reduced computational complexity of the proposal. Moreover, an original statistical analysis is presented as a means to demonstrate the low dispersion of the PSO-based procedure. Experimental results are provided in order to demonstrate the performance of the wind energy conversion system operating with optimal parameters.

Resumo em Inglês:

ABSTRACT The present paper proposes three methods to reduce the torque ripple in Permanent Magnet Synchronous machine by decreasing the cogging torque peak and back-EMF harmonic content. These methods consider the pole segmentation technique, but the distribution and width of the segments are determined by PWM techniques. Sinusoidal, trapezoidal and harmonic injection PWM are assigned to Methods 1, 2 and 3 in that order. This methods can decrease the cogging torque peak and also improve the harmonic content of the back-EMF, thus reducing the torque ripple. Furthermore, the methods were validated by means of a finite elements analysis. Method 3 achieved the best results for both 4- and 8-pole machines, reducing the cogging torque peak by up to 79.53% and increasing the average torque by 6.43%. It also reduced the magnet volume in the 4-pole machine.

Resumo em Inglês:

ABSTRACT Switching losses have been shown to have a significant impact on the efficiency and thermal management of power electronic systems, particularly in high-performance converters. Conventional estimation techniques frequently rely on deterministic parameters, which are unable to account for the inherent variability in semiconductor characteristics and gate-driving conditions. This limitation can result in erroneous predictions and an underestimation of design margins. In order to address this issue, the present paper proposes a probabilistic approach for estimating switching losses in MOSFETs, with applications demonstrated for both Silicon carbide (SiC) and Silicon (Si) devices, using the Monte Carlo method. The methodology involves treating key device and driver parameters, such as gate resistance, transconductance, and threshold voltage, as statistical variables. This approach enables the capture of inherent uncertainties in device behavior. The switching transients are characterized through Double Pulse Test (DPT) simulations across a wide range of voltage and current levels. Monte Carlo simulations are extensively performed to derive the statistical distribution of energy losses, ensuring realistic performance expectations under variable conditions. The findings indicate that parameter variability can lead to substantial discrepancies in switching loss predictions, underscoring the limitations of conventional deterministic methods. The proposed methodology provides a more robust and reliable foundation for thermal design, loss prediction, and reliability assessment in power converter applications, ultimately ensuring improved performance and increased lifespan of power electronic systems.

Resumo em Inglês:

ABSTRACT The most common motor used for industrial, residential and commercial applications is the induction motor (three or single phase). This motor is very reliable, but faults still may occur. The present paper focuses on the diagnosis of induction motor faults based on its temperature and vibration behaviors on steady-state operation. The proposed method is based on the Extended Park Transform, enabling sensor fusion which reduces the amount of data required for fault identification to 1/3 and allows the usage of a shallow artificial neural network. To validate the proposed method, experiments have been carried using a single phase induction motor operating under normal and fault conditions (short-circuit between main winding turns, auxiliary turns, main-auxiliary windings and with contaminated bearing lubrication). The results proves the efficacy of the proposed method, which has reached an accuracy over 99.5% in the process of fault identification using low cost sensors/equipment.

Resumo em Inglês:

ABSTRACT The continuous development of photovoltaic and energy storage systems has enabled the emergence of microgrids, which can operate with alternating or direct current (DC), depending on the components characteristics. Since photovoltaic panels and battery storage systems operate in DC, connecting them via a DC bus simplifies power conversion, especially for DC loads. A key challenge in microgrids is defining an effective control strategy, which may be centralized, decentralized, or distributed. In this sense, the main proposal of this paper consists in the development of a decentralized control strategy for a stand-alone DC microgrid with photovoltaic generation and battery energy storage, using a controlled voltage droop, based on virtual impedance. This paper aims to contribute with the description of the implementation steps of the local controllers, using classical control techniques based on transfer function modelling. In addition, the assembling steps of a low-cost and small-scale DC microgrid prototype are presented. The control approach maintains DC bus voltage within an appropriate range without requiring communication among system components. Moreover, it supports modular expansion by enabling the seamless integration of new generation or storage units. To validate the strategy, a microgrid prototype was developed using a 60 W PV panel, a 12 V, 7 Ah lead-acid battery, and the BOOSTXL-3PhGaNInv evaluation module with a F28379D digital signal controller for converter implementation. Experimental results, including the battery charging process and variations of solar irradiance and load demand, demonstrate the effectiveness and robustness of the proposed control system.

Resumo em Inglês:

ABSTRACT This paper presents the development and validation of a high-reliability three-phase voltage source inverter, designed with field-oriented control (FOC) and space vector modulation (SVM) techniques for use in a Formula Student electric vehicle. Emphasis was placed on achieving efficient power conversion, robust control under variable conditions, and seamless integration with the vehicle’s high-voltage and telemetry systems. The inverter was initially validated through Hardwarein-the-Loop (HIL) simulations, followed by bench testing to refine control loop performance, sensor feedback conditioning, and fault protection strategies. Real-world operation during the 2024 Formula SAE Brazil competition demonstrated the inverter’s effectiveness, achieving consistent performance, energy efficiency, and thermal stability under dynamic racing conditions. The system’s design and validation methodologies contributed directly to competitive success, with the inverter achieving the highest evaluation score in the powertrain category. These results confirm the inverter’s robustness, efficiency, and suitability for high-demand electric drive applications, offering a strong foundation for future advancements in vehicular power electronics systems.

Resumo em Inglês:

ABSTRACT In this paper, a bidirectional converter with low voltage stress is evaluated. The converter is based on a switched inductor technique combined with a switched capacitor in a voltage multiplier structure, enabling a higher voltage gain while maintaining reduced stress on the switching components. Both dynamic and static modeling are developed to provide a comprehensive understanding of the converter behavior and a control strategy is proposed to ensure stable operation under varying load and input conditions. To validate the theoretical analyses, a hardware prototype was designed and implemented, operating at 80-500 W with an input to output voltage range of 72-400 V. Experimental tests were conducted under different operating conditions, confirming the effectiveness of the proposed converter. A peak efficiency of 98.4% was achieved at 250 W, demonstrating the high performance of the converter. Additionally, the ability to reverse power flow online without requiring shutdown enhances its applicability in renewable energy systems and energy storage interfaces.

Resumo em Inglês:

ABSTRACT This paper proposes a novel virtual system-based online tuning strategy for initial gains of adaptive controllers applied to grid-tied converters with LCL filters. The method relies on the implementation of a robust model reference adaptive control (RMRAC) law combined with a full adaptive super-twisting sliding mode action and a disturbance rejection mechanism. To auto-tune the related adaptive gains, a virtual system is excited by a frequency-rich reference signal, ensuring persistent excitation of the regressor and fast convergence of the adaptive gains before the inverter is connected to the physical grid. Once convergence is achieved, the tuned controller is seamlessly transferred to the real plant, where the reference is provided by a grid synchronization unit based on a Kalman filter phase-locked loop. Experimental results demonstrate smooth synchronization, bounded control signals, reduced transient responses, and improved robustness against parametric uncertainties, load disturbances, and grid harmonics, while maintaining acceptable current THD levels. Beyond this case study, the proposed auto-tuning approach can be extended to other RMRAC-based adaptive control schemes, as long as the plant can be properly modeled and simulated, enabling initial gain adjustment without empirical tuning or offline optimization.

Resumo em Inglês:

ABSTRACT This paper presents a containerized development platform suitable for developing and validating advanced microgrids (MGs). Through a collaborative effort involving the Federal University of Minas Gerais (UFMG) within the technical-scientific research project titled Minirrede Oasis-UFMG and the State and Federal government, the Tesla containerized MG emerges as a physical simulation tool on advanced MG projects in both islanded and grid-connected operating modes. Installed at the Tesla Laboratory located in the UFMG School of Engineering, Brazil, Tesla MG is composed of (i) eleven distributed energy resources (DERs), which supply around 33 kW; (ii) one single-phase gas-driven synchronous generator (SG), with a power rating of 11 kW; (iii) one 7.5 kW three-phase diesel-driven SG; and (iv) 30 kVA 4-quadrant programmable AC load and source. All these devices are commercially available off-the-shelf equipment. Photovoltaic modules and different battery technologies are installed outside and inside the container, respectively, with cabling extending to the container to connect these components to the inverters. Hardware-in-the-loop (HIL) platforms for real-time simulations (i.e., Opal RT OP5700 and Typhoon HILs 402 and 604) are also available to support MG research. Experimental results are provided to demonstrate the capabilities of the Tesla MG, specifically focusing on inverter features, power dispatchability in grid-connected mode, and proper operation in islanded mode.

Resumo em Inglês:

ABSTRACT Local solarimetric stations (LSS) are essential for collecting data to evaluate photovoltaic (PV) plant performance and improve simulation accuracy. When unavailable, commercial solar databases (CSD), typically derived from satellite-based typical years, are used. This study compared the impact of LSS and CSD data on PV simulations and explored the use of LSS data for anomaly detection. Two LSS were analyzed: one at a small-scale PV system (minigeneration in Brazil) and another at a large-scale PV plant. The minigeneration station measured irradiance components to calculate Plane of Array (POA) irradiance, while the large-scale station directly measured POA. For the minigeneration system, simulations using LSS data showed a lower discrepancy (0.21%) compared to CSD (3.13%). For the large-scale plant, a -5.99% discrepancy using LSS revealed anomalies in energy generation. MAE and RMSE improved significantly with LSS for the large-scale system, with MAE decreasing from 660.25 MWh (CSD) to 348.08 MWh. Additionally, an unsupervised anomaly detection flagged 2.88% and 4.47% of data for two inverters, showcasing LSS potential for predictive models. These findings suggest that while LSS data are valuable for PV plant performance analysis, their effectiveness may depend on spectral range, averaging intervals, and irradiance transposition in simulations.

Resumo em Inglês:

ABSTRACT In this paper, the performance of a shunt active power filter using direct power control based on the hysteresis method and model predictive control is discussed. Furthermore, an optimized vector selection is presented for model predictive control. This paper’s objective is to evaluate the processing time, reduction of harmonic components that would be injected into the electrical grid by a non-linear load, power semiconductor losses, average switching frequency and root mean square error for the control variables. The comparison uses the same system model and parameters for both strategies. Simulation and experimental results are presented. Using the strategy discussed in this paper, it was possible to reduce harmonic components in the electrical grid, with reduced time for vector selection.

Resumo em Inglês:

ABSTRACT This paper presents a high-gain three-phase interleaved rectifier operating in DCM, with dual input, for application in small wind generators. The two input diode bridges promote the sharing of the current, resulting in a significant reduction of the converter’s current stresses when compared to previous topologies. A theoretical analysis of the proposed converter was performed, followed by a simulation study, and experimental tests with a physical prototype. The simulations compared the proposed three-phase rectifier with three other three-phase topologies, demonstrating its operation with significantly reduced current stresses and smaller input inductors. The experiments compared the operation of the converter when working with a three-phase power supply, and a wind turbine in association with an MPPT method using the Perturb and Observe (P&O) technique. For an output power of 1 kW, on a 400 V DC bus and an input RMS line voltage of 114 V, the structure’s obtained efficiency was higher than 95%. Furthermore, the experimental results confirmed that the rectifier operates with sinusoidal input currents, low current ripple, and high power factor for all the tested scenarios.

Resumo em Inglês:

ABSTRACT This paper presents and discusses challenges in microgrids (𝜇Grid) that arise when they operate isolated from the main grid. Specifically, these challenges occur because the system becomes an ungrounded delta configuration, and the microgrid power sources exhibit low short-circuit capacity. The important issues addressed include the failure to detect ground overcurrent during an earth fault event, voltage imbalances recorded by voltage transformers (VTs) connected between phases and earth, and the phenomenon of ferroresonance. These issues directly impact the coordination of electrical protection, component integrity, and synchronization checks between different power sources within the 𝜇Grid. Therefore, the Energy Management System (EMS) is tasked with managing protection devices and systematically responding to minimize disruptions, thereby ensuring operational security. This paper examines the protection functions within devices for both operational modes (on-grid and off-grid) and the corresponding decisions implemented as rules within the EMS. Effective coordination between protection devices and management systems ensures a rapid and selective response to faults, thereby enhancing microgrid security and facilitating efficient problem detection and resolution.

Resumo em Inglês:

ABSTRACT This paper proposes a reduced-computation-burden Finite Control Set - Model Predictive Control (FCS-MPC) applied to a dual-converter-based rectifier with a floating DC link. The main goal of this paper is providing a proof of concept of the discussed system employing the proposed FCS-MPC, highlighting its feasibility, simple multivariable control and straightforward implementation. The proposed FCS-MPC reduces the number of tested vectors from the available 64 to only nine, efficiently controlling grid currents and floating DC-link voltage. To evaluate the performance, steady- and transient-state simulations were carried out to compare the proposed FCS-MPC with the conventional PI-based method. The results indicate that FCS-MPC provides a better dynamic response than the PI-based method. However, its total harmonic distortion (THD) at the same sampling frequency is higher, as the PI-based method benefits from a modulation stage that reduces the current ripple. Additionally, the proposed FCS-MPC shows significantly lower switching losses than the PI-based approach. On the other hand, for the same switching frequency, the proposed FCS-MPC presents a somewhat higher, but similar THD and losses values to the PI-based method. Experimental results further validate the feasibility of the proposed FCS-MPC, reinforcing its potential as an efficient alternative to traditional control strategies in dual-converter-based-rectifier.

Resumo em Inglês:

ABSTRACT Micro and mild hybrid electric vehicles can make a significant contribution to reducing emissions and mitigating the environmental impact. Electric machine designs with fewer or no rare-earth permanent magnets will play an important role in the adoption of hybrid solutions. Doubly salient reluctance machines exhibit a simple structure, robust mechanical strength, excellent fault tolerance, and a wide range of speed regulation, which makes them suitable for in-wheel applications. Particular emphasis should be placed on flux-switching machines with wound-field excitation, which offer great operating flexibility, efficient heat dissipation, and power density of up to 4.8 kW/kg. This paper introduces a wound-field flux-switching machine designed for in-wheel applications, featuring individual field current control. The machine has individual access to each of the field coils. The primary objective of this research is to enhance the machine’s operational versatility by enabling multiple configurations of the machine, adjusting the way the field-coils are connected. Firstly, a comparison of the armature no-load induced voltage is made for field coils connected in both series and parallel. Additionally, an assessment of the impact of open-circuit failures in one and two adjacent field coils is conducted. Finally, a current control strategy is proposed to effectively manage each individual field coil.

Resumo em Inglês:

ABSTRACT This paper proposes multiple control actions applied to centralized advanced microgrids (MGs). The well-established control actions feedback (FB), feedforward (FF), and disturbance decoupling (D) commonly used in current control of distributed energy resources (DERs) are herein extended to advanced MGs. Analytical expressions are derived to show the effect of each control action on the wellestablished DER current control and then on advanced MG control. Comprehensive comparisons between the feedback and all control action strategies are performed for both DER and MG controls. Simulation and experimental results show a dynamic response improvement in load disturbance rejection when all control actions are considered, as well as a reduction in steady-state error for the grid power flow control. By employing low-bandwidth communication between DERs and central controller, no hardware retrofit is required in comparison to what is needed in other state-of-the-art centralized MG controls.

Resumo em Inglês:

ABSTRACT The Electrical Machines course requires dedication from students, which is essential for their professional qualification because several economic sectors such as industrial and commercial use electrical machines to drive loads. Aiming the training process of engineering students to encompass the development of technical skills, cognitive skills, and methodological skills, the National Curricular Guidelines (DCN) for Engineering courses in Brazil were revised and published to stimulate institutions to adopt active learning methods. This article presents the results of the Team-Based Learning application in the Electrical Machines Classes. In this research, the strategy was used to improve the learning of the students and develop collaborative work skills. From the analysis of the students’ grades obtained in the academic exams from 2010 to 2022 in the Electrical Machine Course of the Federal University of Ceará - Campus Sobral, the topics of Direct Current Machines, Three-phase Transformers, and Synchronous Machines were selected for applying the methodology in 2023. The result is the improvement and leveling of grades in the 2023 semesters.

Resumo em Inglês:

ABSTRACT This manuscript proposes a multiple-input, multiple-output (MIMO) model for an engineinduction generator set in series hybrid/flex vehicles (SHVs). The model outputs are simplified using linear combinations of the inputs via a steady-state gain matrix, with gains defined in terms of the SHV electrical parameters. A reduced-order model is proposed to reliably analyze the dynamic behavior by incorporating the state variables of the powertrain’s electrical system. This facilitates the design of energy management systems (EMS) and power converter sizing, enhancing the efficiency of the enginegenerator set. The mathematical solution was validated through simulations and experimental results, including mechanical power calculations derived from vehicle dynamics applied to an SHV laboratoryscale prototype. Experimental findings demonstrated the effectiveness of a simple EMS in reducing fuel consumption while maintaining the internal combustion engine within its optimal efficiency region. Furthermore, this study presents a practical and cost-effective alternative for ICE-generator systems by replacing permanent magnet synchronous generators (PMSGs) with induction generators (IGs).

Resumo em Inglês:

ABSTRACT The applications and implemented volume of lithium-ion batteries have been gaining momentum each year. Aiming to contribute to the development of research in this area, this paper presents the design and implementation of an electronic load focused on characterizing parameters inherent to equivalent circuit models (ECM). ECMs are commonly applied for estimating the State of Charge (SoC), State of Health (SoH), and Remaining Useful Life (RUL) of lithium batteries. In this paper, an electrical design of an electronic load was implemented and validated through laboratory instrumentation to obtain characteristic data from a lithium titanate cell. The data from the tests performed on the cell were used as input for a SoC estimation algorithm based on the Extended Kalman Filter (EKF) to help corroborate the prototype's performance. The results comprise the performance of the electronic load, the results associated with the parameterization tests of the lithium cells, and the results obtained for the cell’s SoC estimation using the EKF.

Resumo em Inglês:

ABSTRACT The application of hybrid semiconductor switches (HyS) emerges as a solution to the increasing demand for higher switching frequency and power density at a competitive cost. This paper investigates a HyS based on Si-IGBT (silicon-insulated gate bipolar transistor) in parallel with a SiC-MOSFET (silicon carbide-metal oxide semiconductor field effect transistor), highlighting the main characteristics and challenges to obtain a cost-effective device. Simulations in PLECS and LT-Spice reveal significant phenomena that arise during the conduction and switching of HyS devices. Experimental tests conducted on a double pulse test circuit validate the initial analyses and compare HyS switching losses with the standard solution based on IGBT. Finally, some insights on this technology are provided.

Resumo em Inglês:

ABSTRACT This paper aims to analyze the effect of high penetration of floating offshore wind-based power generation on the power quality of a Floating Production Storage and Offloading (FPSO) power system. The paper focuses on the continuous frequency variation caused by intermittent wind power generation and an energy storage-based solution for power smoothing. A set of results simulated in MATLAB/Simulink® is shown to assess different operational scenarios of a typical Brazilian FPSO from the Mero Oil Field, powered by 109 MVA/ 87 MW from three synchronous generators, without wind power. Wind power penetration varies from 10 to 50 MW, and the effects of this variation on FPSO power quality are reported. Then, the number of gas turbine generators is reduced from 3 to 2 generators. Finally, the energy storage for power smoothing purposes is evaluated. Conclusions are drawn based on steady-state and transient voltage and frequency profiles, active and reactive power flow between loads and generation, the rate of change of frequency, and frequency nadir.

Resumo em Inglês:

ABSTRACT Leakage current is an issue that often causes problems in transformerless grid-connected PV inverters, such as electromagnetic interference, which is conducted or radiated and derates the quality of power injected into the grid. It can also lead to electrical safety problems, impair the performance of other equipment nearby, and thus make the generation system unavailable. Therefore, mitigation procedures for the leakage current in transformerless grid-connected PV inverters are essential to ensure system efficiency and safety. In this sense, a new single-phase grid-connected transformerless inverter topology was proposed using modulation switching techniques to keep the leakage current at acceptable standard levels. With the proposed topology, by monitoring the leakage current rms value, the inverter can be driven in a three- or five-level pattern for the main switches, thereby keeping the leakage current at a satisfactory level. The topology was implemented in a versatile hardware-in-loop Typhoon-HIL to emulate a digital twin of the complete system, with the control loops and switching generation embedded in a family Texas Instruments F28335 DSP. The results obtained for total harmonic distortion and energy conversion efficiency were then compared with other consolidated topologies, and the leakage current was proved to be effectively modified when the inverter is switched in three- or five-level modes.

Resumo em Inglês:

ABSTRACT This work presents a droop-based control strategy for a dc nanogrid designed to operate under the Net Zero Energy (NZE) concept, enabling seamless transitions between grid-connected and islanded modes. The nanogrid integrates photovoltaic (PV) generation, a fast electric vehicle charging station (EVSE), and a battery energy storage system (BESS) into a 700 V dc bus interfacing with the ac grid via a bidirectional three-phase AC-DC converter. An isolated DC-DC converter establishes a secondary 48 V dc bus for powering dc loads. An energy management system (EMS) defines an optimal day-ahead power dispatch for the BESS to meet NZE objectives. At the primary control level, a modified power-to-voltage droop strategy ensures accurate power tracking and parallel operation with the AC-DC converter. This approach enables continuous voltage regulation of the main bus under instantaneous power imbalances caused by schedule deviations or operational mode transitions. Additionally, the proposed strategy eliminates the need for secondary control or high-bandwidth communication. The system is validated through hardware-in-the-loop (HIL) simulations using the Typhoon HIL 604 platform, with the control strategy implemented on a DSP. Real-time simulation results confirm stable performance under various operating conditions, including transitions between modes.

Resumo em Inglês:

ABSTRACT The expansion of DC microgrids has prompted investigations into wind energy systems to harness the benefits of this configuration. Therefore, this study aims to analyze and compare the performances of predictive current control (PCC) and predictive flux and torque control (PTC) applied to a doubly-fed induction generator which has its stator windings connected to a DC microgrid by means of a diode bridge. This system is commonly known as DFIG-DC. The system’s performance was evaluated in terms of electromagnetic torque ripple, rotor flux ripple, and current distortion across a range of operating speeds. Although PCC and PTC applied to DFIG-DC have been discussed in previous works, a systematic comparison between them lacks in the literature, which is the main contribution of this paper. In addition, this work discusses the robustness of both methods under parametric errors of stator and rotor resistances, and magnetizing inductance, which has not been approached before.

Resumo em Inglês:

ABSTRACT This work presents an enhanced power-based control technique for controlling the battery current in a quasi-impedance source converter (qZSC) topology with a feed-forward control loop in order to improve disturbance rejection. Such topology can integrate a photovoltaic array and a battery storage system (BSS) using a single inverter bridge. However, the control strategies for managing the energy stored in the battery for this topology are vulnerable to disturbances in the photovoltaic power and have a high level of complexity, especially in terms of mathematical modeling. Therefore, the proposed control method aims to improve this functionality by implementing a cascade control based on the active power between the qZSC and the grid. Therefore, the dynamic model relating the battery current and the qZSC active power output will be demonstrated, as well as the respective closed-loop controller design. The simulation and control hardware-in-the-loop (C-HIL) results demonstrate the effectiveness of the proposed modeling and control technique.

Resumo em Inglês:

ABSTRACT This work presents the quantitative and qualitative analysis, as well as the experimental results of a practical implementation of the Single-Phase Bridgeless Hybrid Switched Capacitor Rectifier operating in discontinuous conduction mode (DCM) to achieve a high input power factor. Operating in DCM provides several advantages, including natural power factor correction (PFC) behavior of the input current and reduced semiconductor switching losses. The paper begins with a literature review on key studies of hybrid switched-capacitor converters with a high power factor. Subsequently, the converter analysis, including its modulation scheme, operational stages and design methodology, is detailed. The proposed approach is validated with results from a practical prototype implementation, achieving an output voltage of 1200 V and an output power of 315 W from an input voltage of 220 V. The converter demonstrated an efficiency of 97.3%, a power factor of 0.99, and harmonic distortion levels within the limits specified by IEC61000-3-2.

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ABSTRACT The growing demand for energy in remote and isolated regions, where access to the conventional electrical system is limited, has been driving the development of off-grid systems. A common type of off-grid power system employs photovoltaic systems associated with battery banks. However, these systems face challenges due to their remote location and their reliance on weather conditions for energy generation. Furthermore, it is crucial that these systems can communicate operational discrepancies, notify maintenance teams, and receive commands to activate energy-saving modes during adverse weather conditions. This work presents a simple and cost-effective approach to enhance the operation of an off-grid system, transforming it from a conventional system into an intelligent operation using the cloud-based platform known as “thingable!”. The results highlight a cloud interface creation that enables the control of a pumping system. This interface is enabled by monitoring operational parameters, such as voltage, IGBTs temperature, and power delivered. To validate the proposed changes, a monitoring test was carried out using a controlled pump from 9:10 a.m. to 10:10 a.m., powered by an inverter connected to a 100 V DC bus. Additionally, a test was conducted to assess the pump behavior under a fixed duty cycle of 60%.

Resumo em Inglês:

ABSTRACT The ABNT NBR-16149 and NBR-16150 standards and INMETRO Ordinance No. 140 establish requirements for connecting PV inverters to the Brazilian electrical grid. To meet these requirements, the firmware of these devices needs to be properly designed and validated. Additionally, it is important to perform tests to verify whether the inverter and its control systems comply with the standards. In this context, this paper presents a methodology for the validation of controllers for PV inverters using Hardware-in-the-loop (HIL). To validate the proposed methodology, a two-level three-phase PV inverter with Finite Control Set Model Predictive Control (FCS-MPC) for current control and additional control and grid connection functionalities was evaluated. The compliance of the controller with relevant standards was assessed through automated HIL testing. This approach allows control designers to identify potential issues in advance, refine algorithms, and enhance controller performance before the complete hardware certification process of the inverter.

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ABSTRACT This paper introduces INEP PVSim, an offline application designed for teachers, students, and engineers to evaluate the behavior of photovoltaic (PV) modules. The application features a user-friendly interface that allows the simulation of I–V and P–V curves under different climate conditions, enabling real-time modification of parameters such as solar irradiance and temperature across a much broader range than typically provided in manufacturer datasheets. INEP PVSim is developed as free Python-based code and offers significant educational potential in the field of Power Electronics, as analyzing the impact of parameter variations on PV generation is often a challenging task with direct implications for power converter design. In addition to presenting the application, this paper also formalizes, in a single document, the equations and methods adopted for the implementation of the one-diode model, providing an accessible yet accurate platform for both learning and practical analysis.

Resumo em Inglês:

ABSTRACT The current mainstream method of global hydrogen production relies on steam reforming of natural gases, which leads to CO2 emissions. On the contrary, renewablepowered water electrolysis offers a sustainable alternative for hydrogen production. The growing adoption of hydrogen as an energy storage solution holds potential for new applications, including ancillary electric grid and transportation services. Those high-power applications require a high output current (900 A) and relatively low output voltages (160-220 V). To address these requirements, a system is designed from a photovoltaic array, two step-down interleaved converters, and an intermediary DC bus to power a 10-kW electrolyzer. The first stage allows the implementation of the maximum power point tracking of the photovoltaic array, ensuring optimal energy conversion, while the second stage supplies the electrolyzer with constant current. A droop-based strategy is proposed to regulate a floating bus voltage within a specified range. Controller Hardware-in-the-Loop results show the feasibility of the proposed control strategy.