Maximum Power Point tracking (MPPT) in photovoltaic (PV) systems may be achieved by controlling either the voltage or current of the PV device. There is no consensus in the technical literature about how is the best choice. This paper provides a comparative analysis performance among current and voltage control using two different MPPT strategies: the perturb and observe (P&O) and the incremental conductance techniques.

Objective: This study aims to review and compare the effectiveness of the SWAT (Soil and Water Assessment Tool) and HEC-HMS (Hydrologic Engineering Center’s Hydrologic Modeling System) models in different watershed contexts, aiming to identify the conditions under which each model performs best for sustainable water resource management. Theoretical Framework: The research is based on concepts of sustainable watershed planning and water resource management. The SWAT and HEC-HMS models are widely recognized in the literature for their robustness and applicability in hydrological simulations, commonly used for surface runoff predictions and environmental risk assessment, particularly in heterogeneous watersheds. Method: A literature review was conducted, focusing on studies published from 2019 onward that directly compared the two models. The selection of papers followed rigorous criteria of contemporaneity, methodological quality, and application in different geographical and climatic contexts. The results of these studies were analyzed and discussed comparatively. Results and Discussion: The results indicate that SWAT excels in simulating high flows and in contexts of high hydrological variability, such as in mountainous regions and humid tropical watersheds. On the other hand, HEC-HMS showed better performance in simulating low flows, particularly in scenarios with limited data availability. The discussion addresses the implications of these results for watershed management and the challenges of selecting the ideal model. Research Implications: This research provides valuable insights for watershed management, highlighting the practical implications of each model in flow prediction and disaster mitigation, such as floods and droughts. Originality/Value: The study contributes to the literature by providing a comparative analysis of the SWAT and HEC-HMS models in various environmental contexts. It reinforces the importance of selecting the most suitable model for each hydrological context.

Este artigo apresenta um aparato educacional para ensino prático de estratégias de controle aplicadas a eletrônica de potência. Este aparato é composto por uma planta eletrônica configurável, um processador digital de sinais, um computador pessoal e placas de circuitos para comunicação e interface. O aparato desenvolvido permite uma interação do usuário, gradual e assistida, em todos os estágios, ou seja, desde a escolha e projeto dos compensadores até a comprovação experimental do comportamento dinâmico da planta sob controle. Os recursos didáticos da ferramenta educacional são ilustrados pelos resultados obtidos com o controle de uma máquina de corrente contínua. Neste caso a configuração selecionada permite operar nos quatro quadrantes, logo permitindo o fluxo bidirecional de energia, ou seja, contemplando motorização e geração. Outro atributo desta configuração é a identificação automática dos parâmetros elétricos e mecânicos da máquina através de um software adicional específico.

Introduction: This study assesses the economic feasibility of implementing electric buses in Juiz de Fora - MG, considering acquisition, operation, and maintenance costs compared to diesel models. The methodology is based on the Total Cost of Ownership (TCO) analysis, considering factors such as charging infrastructure, energy consumption, government incentives, environmental impact, and public policies related to electromobility.The results indicate that, although electric buses present 24% lower maintenance costs and up to 88.9% reduction in electricity expenses when combined with solar energy, the high initial acquisition cost and the need for structural investments compromise their economic feasibility in the short term. Additionally, implementing charging infrastructure represents a significant financial challenge for public transport operators. However, the analysis shows that alternative financing models, such as battery leasing and public-private partnerships (PPPs), can mitigate some of the financial challenges. Furthermore, more robust public policies, such as government subsidies, tax exemptions, and differentiated electricity tariffs, are essential to enable the energy transition in the public transport sector. Thus, this study reinforces the need for economic and regulatory strategies to facilitate fleet electrification, making urban transport more efficient, sustainable, and economically accessible in the long run. Objective: This article aims to analyze the economic feasibility of implementing electric buses in public transport in Juiz de Fora - MG, considering acquisition, operation, and maintenance costs compared to diesel buses. To achieve this, factors such as energy efficiency, charging infrastructure, government incentive policies, and available financing models will be evaluated. Additionally, the study seeks to identify the challenges and opportunities associated with transitioning to an electric fleet in the city, providing subsidies for decision-making by public managers and transport companies. Theoretical Framework: The study highlights the Total Cost of Ownership (TCO) analysis, financing models for electromobility, public policies for sustainable transport, and environmental impacts of fleet electrification, providing a solid foundation for understanding the research context. Method: The methodology adopted in this research follows a quantitative approach, based on Total Cost of Ownership (TCO) analysis and the economic feasibility assessment of fleet electrification. Data was collected from operational cost surveys, energy consumption analysis, and investments in charging infrastructure, supplemented by information from case studies and secondary sources, such as technical reports and industry regulations. Results and Discussion: The results revealed that, despite up to 24% lower maintenance costs and up to 88.9% electricity savings when using solar energy, the high initial cost of electric buses and charging infrastructure compromises their economic feasibility in the short term. In the discussion section, these results are contextualized within the theoretical framework, emphasizing the importance of government subsidies, tax incentives, and alternative financing models to enable fleet electrification. Research Implications: The practical and theoretical implications of this research are discussed, providing insights into how the findings can influence sustainable mobility and electromobility practices. These implications include public policy planning for urban transport, the adoption of financing models for electric fleets, and the feasibility of integrating renewable energy into the sector. Additionally, the findings may contribute to strategies that reduce economic barriers and encourage the transition to a more efficient and sustainable public transport system. Originality/Value: This study contributes to the literature by analyzing the economic feasibility of fleet electrification in a medium-sized city in Brazil, a topic still underexplored in local contexts. The innovative approach includes the integration of solar energy as an alternative to reducing operational costs, expanding the debate on sustainability in public transport. The relevance and value of this research are highlighted by its potential impact on public policy formulation, urban planning, and the adoption of more accessible financial models for energy transition in the mobility sector.

Este trabalho apresenta a modelagem de fontes modulares de corrente, associadas em série/paralelo, utilizadas no Sirius. O modelo proposto ée baseado na teoria de sistemas descritores, e considera a associação de N módulos sperie-paralelo. O modelo matemáatico e o circuito chaveado equivalente são implementados, respectivamente, nos softwares Matlab e PSIM. Os resultados obtidos são satisfatórios em relação a precisão do modelo.