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This article discusses the role of power electronic converters in smart grids and electric vehicle applications. The authors highlight the technical connection between renewable energy, smart grids, energy storage, and electric vehicles. The special issue includes twelve accepted papers that cover topics such as high gain DC-DC converters, power converters for electric vehicle and motor drive applications, and power system applications. The papers present various novel topologies and control techniques, indicating the rapid growth and future potential of power converters in these fields. The authors express their appreciation to the contributing authors and anonymous reviewers for their valuable contributions to this special issue. [Extracted from the article]

Summary: Unified small‐signal modeling approaches are of paramount importance for the design of controllers and closed‐loop control systems in power electronic converters. In this sense, this work proposes the small‐signal analysis of non‐isolated dc‐dc converters employing the three‐state switching cell (3SSC) in discontinuous conduction mode (DCM). The modeling technique relies on the very same principles of the pulse width modulation (PWM) switch while not involving matrix operations, but only basic concepts related to electric circuits. Considering that the waveforms associated with the terminals of the 3SSC in DCM have a common behavior in all basic dc‐dc converters, it is possible to derive the small‐signal models for both operating regions of the 3SSC, that is, non‐overlapping mode (NOM) and overlapping mode (OM). Thus, one can effectively demonstrate that the same circuit can represent both modes, even though the coefficients that describe the models are calculated from distinct equations. The theoretical claims are validated in the frequency and time domains while comparing the model with the converter. The obtained results evidence that the unified model can accurately represent converters based on the 3SSC in DCM. [ABSTRACT FROM AUTHOR]

This work presents a family of single‐phase ac–ac converters with high‐frequency isolation based on the association of interleaved transformers and the dual active bridge (DAB) converter. From distinct configurations of the dc link in terms of half‐bridge (HB), full‐bridge (FB), and interleaved full‐bridge (IFB) arrangements, one can obtain three symmetrical and six asymmetrical structures, with distinct trade‐offs among the number of active switches, total dc‐link voltage, and effective operating frequency of the filter elements. Prominent advantages of the derived circuits include input power factor correction (PFC), a nearly sinusoidal load voltage, the operation of active switches under soft‐switching condition during part of the line period, reduced current stresses, good current sharing due to the interleaved transformers, as well as multilevel voltage waveforms on both sides of the high‐frequency transformer (HFT). Experimental results obtained from an experimental prototype of an ac–ac FB‐IFB converter are presented to validate the theoretical assumptions. [ABSTRACT FROM AUTHOR]

The doubly fed induction generator (DFIG) and back-to-back converter are very sensitive to power quality disturbances in grid-connected wind energy conversion systems (WECSs). Special attention has been given to protect the system from voltage sags, considering the introduction of several low-voltage ride-through (LVRT) techniques in the literature. However, only few works have really analyzed the behavior of power semiconductors during such phenomena in terms of the thermal stresses, whereas the existing studies are focused on balanced voltage sags only. In this context, this work presents a thermal profile analysis of power semiconductors in the grid-side converter (GSC) and rotor-side converter (RSC) considering a DFIG-based WECS submitted to symmetrical and asymmetrical voltage sags. The system is modeled using PLECS software and results on a 2.0 MW system are presented and thoroughly discussed. The results show that it is possible to meet the ride-through requirements during both balanced and unbalanced sags in terms of acceptable thermal stresses on the semiconductors as long as the back-to-back converter and its respective control system are properly designed. [ABSTRACT FROM AUTHOR]

Solid-state transformers (SSTs) have emerged as an interesting solution for replacing the traditional low-frequency transformers in power distribution systems owing to the capacity of performing ancillary services and providing the integration of multiple energy sources. This article proposes a four-port, single-phase, multidirectional ac–ac converter for SST applications. Considering the integration of conversion stages, it is possible to achieve higher efficiency and lower component count when compared with the typical three-stage topologies reported in the literature. The introduced structure is based on the interleaving concept associated with the well-known dual active bridge converter. The medium-voltage side employs a multilevel neutral-point-clamped converter. The voltages across the ac ports present five levels, whereas the operating frequency of the filter elements is twice the switching frequency. Experimental results are presented and thoroughly discussed to validate the theoretical assumptions. [ABSTRACT FROM AUTHOR]

This work presents a non‐isolated DC–DC boost converter employing coupled inductors, a diode‐capacitor network, and a voltage multiplier cell (VMC). This converter allows extending the conversion ratio not only by increasing the turns ratio of the coupled inductor, but also by adding more networks and VMCs, resulting in a more flexible design approach. Unlike most coupled‐inductor‐based boost‐type converters reported in the literature, the topology presents an output stage whose current is non‐pulsating, which leads to reduced electromagnetic interference (EMI) levels. Other prominent advantages include the fact that the input current is non‐pulsating with low high‐frequency ripple, as well as the operation of the switch and output diode under soft‐switching condition. Experimental results obtained from a 200‐W prototype are presented and discussed to validate the theoretical assumptions, also showing that the converter has high efficiency over a wide load range. [ABSTRACT FROM AUTHOR]