Active resonant tank to achieve zero-voltage-switching for non-isolated DC-DC converters with synchronous rectifiers
ABSTRACT A concept of active resonant tank (ART) is proposed for high frequency non-isolated DC-DC converters to achieve zero-voltage-switching (ZVS) of the main switch and eliminate reverse recovery and body diode conduction losses of the synchronous rectifier in order to improve conversion efficiency and reduce EMI noises. The concept is generalized for six basic non-isolated converters. A buck converter with the ART cell is analyzed in great detail, and a 100 W prototype is built to verify the concept. Experimental results agree with theoretical analysis and improvement in efficiency is achieved due to the reduced switching and reverse-recovery losses
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- "Many circuit topologies of DC/DC converters have been studied in order to obtain high efficiency   . Resonant type converters, which use zero current switching or zero voltage switching, are a good solution to obtain high efficiency  . "
ABSTRACT: This paper proposes a new buck-boost DC/DC converters, which is connected in series to the power supply. The proposed circuit provides only differential voltage between the input voltage and the output voltage command. The power rating of a conventional circuit is dominated by the input voltage or the output voltage. In contrast, the voltage rating of the proposed circuit requires only the differential voltage between the input and output voltage. In addition, the series converter generates a positive and negative voltage to realize boost mode and buck mode, respectively. As a result, the power rating of the DC/DC converter can be drastically reduced. A new approach for series compensation converters is introduced in order to realize high efficiency and a reduction of power rating. Two new buck-boost converters and their control methods are proposed based on a new concept in which the proposed circuits consist of an Hbridge circuit and a power assist circuit. The H-bridge circuit is used in order to determine the polarity of the differential voltage. The power assist circuit controls the DC voltage of the H-bridge circuit depending on the output voltage command. In the proposed circuit, a flyback converter and inverting chopper are used as the power assist circuit. Simulation and experimental results are shown in order to demonstrate the advantages of the proposed converters in comparison with a conventional buck-boost converter. A maximum efficiency of 98% was obtained with the proposed circuit. The proposed circuits can decrease losses by 2/3 in comparison with a conventional buck-boost converter. Therefore, the proposed converter can realize high efficiency and down-sizing in applications that require the output voltage to be closed to the input voltage.Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008
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ABSTRACT: Research on the reverse current phenomenon in synchronous rectifiers (SRs) is presented in this paper. For loss reduction, the SRs composed of metal-oxide-semiconductor field-effect transistors (MOSFETs) have recently been employed to replace the conventional rectifiers with diodes in low-voltage and high-current applications. Because the MOSFETs in the SRs are used as bidirectional switches, reverse current flow will probably occur. The reverse current phenomenon will cause undesired power loss. To clarify the effects of the reverse current on the forward converter with an SR, both the experiment and the analysis are performed. Furthermore, the concepts and methods for dealing with this phenomenon are clearly described in this paper.IEEE Transactions on Industrial Electronics 05/2008; 55(4-55):1570 - 1575. DOI:10.1109/TIE.2008.917106 · 6.50 Impact Factor