249 documents found, page 1 of 25
Sensorless current control: an experimental validation applied to a DC-DC Buck ...
Dias, Ana; Morais, Rosalina; Afonso, João L.; Monteiro, Vítor Duarte FernandesThe dependence of power electronics converters is increasingly unquestionable, where a vast majority of topologies can be used supported by digital control algorithms. Normally, control requires the use of sensors, however, although less considered, sensorless techniques can also be applied, offering the possibility of reducing the hardware necessities, while increasing the control requirements. This paper prop...
Planar transformer design for a LLC DC-DC converter with variable input and wid...
Loureiro, Pedro; Amin, Saghir; Awais, Muhammad; Afonso, João L.; Monteiro, Vítor Duarte FernandesDC-DC converters are fundamental to electric vehicle (EV) fast charging infrastructures, where the LLC DC-DC resonant converter is widely adopted due to its soft-switching capability, high efficiency, galvanic isolation, and wide output voltage regulation. The high-frequency transformer in the LLC converter plays a key role in achieving such features, as well as for ensuring high power density. This study prese...
A conceptual design of multibus architectures for smart homes in residential DC...
Coelho, Sérgio; Rocha, João; Sepulveda, Manuel J.; Monteiro, Vítor Duarte Fernandes; Afonso, João L.Hand to hand with the ongoing energy transition, this paper proposes a conceptual multibus architecture for smart homes, designed to improve flexibility, efficiency, and scalability of residential DC microgrids. The proposed solution centralizes DC distribution at 800 VDC using the first conversion stage of a solid-state transformer (SST), while the subsequent two stages are allocated at the smart home level. I...
Design and Implementation of a DC–DC resonant LLC converter for electric vehicl...
Rocha, João; Amin, Saghir; Coelho, Sérgio; Rego, Gonçalo; Afonso, João L.; Monteiro, Vítor Duarte FernandesThis article presents the design and implementation of a DC–DC power converter for application in electric vehicle (EV) fast-charging systems. The prototype is of the resonant LLC type and consists of a high-power transformer operating at high frequency, which is an essential feature for the adequate behavior of the EV fast-charging system as a whole. As demonstrated throughout the article, by using this conver...
Variable DC-Link voltage for an LLC converter with wide input and output voltag...
Rocha, João; Amin, Saghir; Awais, Muhammad; Rego, Goncalo; Afonso, João L.; Monteiro, Vítor Duarte FernandesThis paper introduces an LLC converter with a variable input DC-link voltage, aimed to address the challenges of single stage DC-DC converter with wide output voltage range associated with electric vehicle (EV) fast chargers. The proposed design optimizes the input/output voltage ratio to enhance efficiency across a wide range of charging operating power values. The analysis highlights the converter's ability t...
A battery-oriented multiport DC-DC converter for enhanced power management in SST
Coelho, Sérgio; Monteiro, Vítor Duarte Fernandes; Afonso, João L.In response to the growing demand for technological solutions aimed at enhancing the stability of electrical power systems, this paper proposes a new approach to power flow management in solid-state transformers (SST). Within the context of smart grids, the increasing integration of renewable energy sources (RES) introduces greater uncertainty and variability, making it critical to balance mismatched generation...
A novel unified single-phase active rectifier topology with advanced operating ...
Monteiro, Vítor Duarte Fernandes; Costa, Filipe; Coelho, Sérgio; Afonso, João L.Active rectifiers are of paramount importance for guaranteeing power quality in smart grids, due to their characteristics of sinusoidal current consumption and unitary power factor operation. In this paper, a novel unified single-phase (USP) front-end converter is proposed for active rectifier applications in smart grids, offering additional advantages and a set of relevant features besides the conventional act...
Solid-state transformer: the catalyst for resilient and sustainable smart grids
Coelho, Sérgio; Dionizio, Anderson; Cunha, José; Monteiro, Vítor Duarte Fernandes; Afonso, João L.This paper explores the transformative role of solid-state transformers (SSTs) in enhancing the performance of smart grids and microgrids, focusing on their technological capabilities and contribution to sustainability. Renowned for their flexibility, adaptability, and scalability, SSTs are crucial for improving the resilience of electrical systems, particularly in dynamic infrastructures with multiple load and...
Planar transformer design for a LLC DC-DC converter with variable input and wid...
Loureiro, Pedro; Amin, Saghir; Awais, Muhammad; Afonso, João L.; Monteiro, Vítor Duarte FernandesDC-DC converters are fundamental to electric vehicle (EV) fast charging infrastructures, where the LLC DC-DC resonant converter is widely adopted due to its soft-switching capability, high efficiency, galvanic isolation, and wide output voltage regulation. The high-frequency transformer in the LLC converter plays a key role in achieving such features, as well as for ensuring high power density. This study prese...
Topological advances in isolated DC–DC converters: High-efficiency design for r...
Coelho, Sergio; Monteiro, Vítor Duarte Fernandes; Afonso, João L.The increasing penetration of renewable energy sources (RESs) into medium-voltage (MV) and low-voltage (LV) power systems presents significant challenges in ensuring power grid stability and energy sustainability. Advanced power conversion technologies are essential to mitigate voltage and frequency fluctuations while meeting stringent power quality standards. RES-based generation systems typically employ multi...