This paper presents an isolated single-stage on-board electric vehicle charger without an intermediate DC-link. Based on an isolated current-source topology, the converter features soft-switching in semiconductors regardless of load variation for the full AC line voltage range. Moreover, it requires no external snubber or clamp circuits. The power factor correction and voltage regulation are provided by a relatively simple phase shift modulation, while the amount of circulating energy is kept at minimum. The charger is distinguished by its efficiency characteristic – the maximum is achieved in the constant power charging mode. The control method, component stresses, and design constraints of the topology are analyzed. The concept is verified using a 3 kW experimental SiC-based prototype, which reaches a peak efficiency of 96.4%. Moreover, the charger has demonstrated efficiencies above 95% with the THD of 4.1% when operating in constant power mode at the maximal power.

Residential dc microgrids and nanogrids are the emerging technology that is aimed to promote the transition to energy-efficient buildings and provide simple, highly flexible integration of renewables, storages, and loads. At the same time, the mass acceptance of dc buildings is slowed down by the relative immaturity of the dc technology, lack of standardization and general awareness about its potential. Additional efforts from multiple directions are necessary to promote this technology and increase its market attractiveness. In the near-term, it is highly likely that the dc buildings will be connected to the conventional ac distribution grid by a front-end ac-dc converter that provides all the necessary protection and desired functionality. At the same time, the corresponding requirements for this converter have not been yet consolidated. To address this, present paper focuses on various aspects of the integration of dc buildings and includes analysis of related standards, directives, operational and compatibility requirements as well as classification of voltage levels. In addition, power converter configurations and modulation methods are analyzed and compared. A classification of topologies that can provide the required functionality for the application is proposed. Finally, future trends and remaining challenges pointed out to motivate new contributions to this topic.

PV systems are penetrating the energy generation market rapidly and their output strongly depends on environmental conditions. To maximize the energy yield, the utilization of power electronic converters with maximum power tracking function is mandatory. Typically, the dc voltage generated by PV is fed into the ac grid using an dc-ac inverter. On the other hand, most modern loads, from small to large ones, are based on dc. Hence, wide adoption of residential dc microgrids (RDC $\mu $ Gs) based on PV energy generation becomes a trend that is following the developments in modern energy-efficient buildings. This paper targets power converters for the integration of PV systems into RDC $\mu $ Gs. It considers two main classes: high step-up converters for PV module-level (parallel optimizer) applications and non-isolated buck-boost converters for the PV string (series optimizer) applications. Due to the importance of the PV topic, a significant number of topologies have been introduced in the literature. However, only selected solutions attracted the interest of the industry. This review paper considers PV converters used in the industry or demonstrated in academic publications at a high technology readiness level with comprehensive experimental justification. This allows us to focus this review on the most valuable solutions and to provide a guide for both industry and academic readers. In the end, future trends in industrial PV systems and associated power converters are discussed.

This paper proposes a bidirectional isolated dc-dc converter topology with the current source and voltage source terminals. Two bidirectional switches in the current-source bridge side and a novel modulation algorithm allow soft switching of all semiconductors even under no-load conditions with a relatively low energy circulation and without any dedicated snubbers or clamp circuits. Zero-voltage switching (ZVS) of high voltage switches can be achieved even at no-load conditions, which allows application of external snubber capacitors to reduce turn-off losses. Voltage regulation is provided using relatively simple phase-shift modulation. Design constraints of the converter are evaluated and analyzed for both energy transfer directions. The steady-state operation is presented and verified experimentally with a 500 W prototype. The efficiency of the power stage reached 96.7% and 97.2% at maximum power in the boost and buck mode, respectively. The converter can be used in renewable, supercapacitor, battery and dc microgrid applications.

This article presents a high gain pure sine- wave inverter based on the full-bridge dc–ac high-frequency link cycloconverter topology for telecom or general-purpose applications. The improved quasi-resonant modulation method allows reduction of ringing and turn- off losses of the dc-side switches. This is achieved with minimal energy circulation and requires no multi-mode operation or extra auxiliary clamping circuits. The soft switching can be provided even if relatively large lossless snubber capacitors are connected across the input side transistors. Moreover, two of the switches at the ac side operate at fundamental frequency, while the rest feature zero current turn- off . A 48 V _DC to 230 V _AC , 1.2 kW sine-wave inverter prototype was developed to verify the proposed concept.