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 multistage power electronics to achieve: (i) maximum power point tracking; (ii) galvanic isolation and voltage transformation; (iii) high-quality power injection into the power grid. In this context, this paper provides a comprehensive review of up-to-date isolated DC–DC converter topologies tailored for the integration of RES. As a contribution to support this topic, recent advancements in solid-state transformers (SSTs) are explored, with particular emphasis on the adoption of wide bandgap (WBG) semiconductors technologies, such as silicon carbide (SiC) and gallium nitride (GaN). These devices have revolutionized modern power systems by enabling operation at a higher switching frequency, enhanced efficiency, and increased power density. By consolidating state-of-the-art advancements and identifying technical challenges, this review offers insights into the suitability of power converter topologies in light of future trends, serving as a valuable resource for optimizing grid-connected RES-based sustainable power systems.

This 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 converter topology as well as its specific operating modes, such as for achieving zero-voltage switching (ZVS) and zero-current switching (ZCS), it is possible to enhance efficiency by reducing conduction and switching losses as well as to increase power density. The details of the high-power high-frequency transformer (HFT), considering different designs, are presented and discussed. With the implemented laboratorial prototype fully developed with silicon carbide (SiC) power semiconductor devices, it was possible to demonstrate and validate the main features of the resonant LLC converter, including high efficiency, under distinct conditions of operation.

This paper deals with the development and experimental validation of a unified power converter for application in dc microgrids, contemplating the inclusion of solar photovoltaic (PV) panels and energy storage systems (ESS), namely batteries. Considering the limitations presented by the current structure of the power grid, mostly highlighted by the accentuated integration of emerging technologies (ESS, renewables, electric vehicles, and electrical appliances that natively operate in dc), it is extremely pertinent to adopt new topologies, architectures, and paradigms. In particular, decentralized power systems, unified topologies, and correspondent control algorithms are representative of a new trend towards a reduction in the number of power converters. Thus, the developed solution is designed to operaSAVE-15te at a nominal power of 3.6 kW, with a switching frequency of 100 kHz, and in four operation modes concerning power flow: (i) solar PV panels to batteries (PV2B); (ii) solar PV panels to dc grid (PV2G); (iii) batteries to dc grid (B2G); (iv) dc grid to batteries (G2B). Moreover, a dual active bridge converter guarantees galvanic isolation, while two back-end dc–dc converters are responsible for interfacing solar PV panels and batteries. The experimental validation of the proposed unified power converter proves its application value to self-consumption production units.

The concept of bipolar dc power grids has emerged, mainly due to the improvements in efficiency and offered flexibility when compared with unipolar architectures. Though, concerns of asymmetrical loads affecting voltage unbalances is the key challenge to overcome. In this context, power electronics play an important influence since the features of the topology contribute to define the quality of the bipolar dc power grids. This paper presents the application of a bipolar bidirectional three-level (BB3L) dc-dc converter as a contribution to mitigate the aforementioned concern of bipolar dc power grids. The proposed BB3L dc-dc converter is introduced, and an insightful description of its principle of operation is presented throughout the paper. Since the BB3L dc-dc converter operates with three voltage levels, it is possible to diminish the blocking voltage of the switching devices, representing an important feature of such topology. Additionally, it can operate with the voltage and current variables controlled with the double of the switching frequency, also representing an added value of such topology. The distinct possibilities of operation are presented, both in buck-mode and boost-mode, and an experimental validation is presented to validate the main features of the BB3L dc-dc converter for bipolar dc power grids.

This paper addresses the comparison and validation of different modulations for an isolated dc-dc dual active bridge converter (DAB), namely, Duty-Cycle Modulation, Single Phase Shift (SPS), Dual Phase Shift (DPS), Extended Phase Shift (EPS) and Triple Phase Shift (TPS). Given the DAB’s applicability in a wide variety of power electronics branches, several control strategies are being studied to improve its efficiency, by mitigating circulating currents and reactive power. Regardless of the chosen architecture, appropriate modulations must be adopted, assessing which one presents the better cost-benefit ratio. This simulation-based analysis aims to investigate the DAB performance when controlled by the above-mentioned modulations and operating with a nominal power of 3.6 kW. Thus, simulation results show that only SPS, DPS, and TPS are considered suitable, while Duty-Cycle Modulation has time limitations during power transfer and EPS is more appropriate for dynamic power applications.