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An isolated converter such as SEPIC has high voltage stress on the main switch due to transformer leakage inductance. To solve this issue, active or passive clamp action is necessary. The common passive solution based on an RCD snubber is simple but impractical when the value of the leakage inductance is significant. On the other hand, passive regenerative solutions generally compromise the isolation, making the search for a suitable snubber a challenge. In this paper, an effective passive regenerative snubber cell for isolated SEPIC converters operating in DCM or CCM is presented. It is intended to improve the converter efficiency by transferring the energy stored in the transformer leakage inductance to the output. The analysis is presented in detail for DCM and extended to CCM together with a practical design procedure. In order to compare with the RCD, the analysis and design of a conventional cell are presented as well. To validate the proposal and quantify its feasibility, experimental results are performed for both dissipative and regenerative snubbers on a 100 W, 100 V, input and 50 V output voltage converter operating first in DCM and later in CCM. [ABSTRACT FROM PUBLISHER]

This paper proposes a bidirectional three-phase direct ac–ac converter, with only capacitors and switches in its power circuit and with its operation based on the switched-capacitor principle. The converter presents fixed gain, it keeps the frequencies of the output and input voltages equal, and it operates in open loop with constant switching frequency and duty cycle. The main advantages of the proposed converter are the absence of magnetic elements in the power circuit, the higher efficiency, the higher power density, the higher specific power, the lower cost, and the fact that it can convert ac–ac voltages within a wide frequency range, including dc voltage. Therefore, it is suitable to replace the conventional three-phase autotransformer in industrial, commercial, and residential applications, and it can be designated as a magnetic-less three-phase solid-state autotransformer. The principle of operation, a qualitative and quantitative analysis, the design methodology, and a fabricated example are described in this paper. In order to verify the converter in the laboratory, a prototype with the following characteristics was designed and fabricated: 6 kW, 1.35 kW/kg, 380/110 V, and switching frequency of 100 kHz. The measured efficiency at rated power was 96.3%, and other relevant experimental results are reported herein. [ABSTRACT FROM PUBLISHER]

This paper proposes a new ac–ac static power converter based on the switched-capacitor (SC) principle, intended to replace the conventional autotransformer in commercial and residential applications. The principle of operation, a qualitative and quantitative analysis, the design methodology, and an example are described in this paper. The main advantages of the proposed ac–ac converter are the absence of magnetic elements, the stress voltages in all components being equal to half of the high-side voltage, the common reference between input and output voltages, the employment of a single SC leg, the ability to be bidirectional, the high efficiency, and the high power density. In order to demonstrate the performance of this converter in the laboratory, a prototype of 1-kW, 220-V rms high-side voltage, 110-Vrms low-side voltage, and switching frequency of 100 kHz was designed and fabricated. The relevant experimental results are reported herein. The maximum and rated power efficiencies obtained in the laboratory were 98% and 96%, respectively. [ABSTRACT FROM PUBLISHER]

This letter proposes an ac–ac converter based on the switched-capacitor principle. The new topology is described, analyzed, designed, and tested in the laboratory. The converter characteristics at the frequency of the input voltage and at the switching frequency are described herein. The absence of magnetic elements and the stress voltages in all components equal to half the input voltage are the main advantages of the proposed ac–ac converter. In order to demonstrate the performance of this converter a design example and experimental results for a prototype of 600 W, 220 Vrms high-side voltage, 110 Vrms low-side voltage, and switching frequency of 50 kHz are reported herein. The maximum and nominal efficiencies obtained were 95.6% and 90.6%, respectively. [ABSTRACT FROM PUBLISHER]