ZVS Resonant Converter With Parallel–Series Transformer Connection
ABSTRACT A new series resonant converter with a parallel-series transformer connection is proposed in order to achieve zero voltage switching (ZVS) for all power switching, zero current switching (ZCS) for rectifier diodes at a full load, and less transformer secondary winding with a full-wave rectifier. For high-output-voltage applications, the primary windings of two transformers are connected in parallel in order to share the input current and reduce the root-mean-square rms current on the primary windings such that the copper losses on the transformers are reduced. The secondary windings of the two transformers are connected in series in order to ensure that the primary side currents are balanced and the secondary winding turns are also reduced. Thus, the sizes of the transformer core and bobbin are reduced. The full-wave diode rectifier is used on the output side. Thus, the voltage stress of the rectifier diode is equal to the output voltage rather than being two times the output voltage as that in a center-tapped rectifier topology. Based on the resonant behavior, all switches are turned on at the ZVS, and the rectifier diodes are turned off at the ZCS if the operating switching frequency is less than the series resonant frequency. The laboratory experiments with a 660-W prototype, verifying the effectiveness of the proposed converter, are described.
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ABSTRACT: A new converter topology is described for applications requiring very low output current ripple. The proposed converter consists of two asymmetric half-bridge converters whose output voltages overlap in a finite interval of time. This converter provides well regulated and smooth dc output without the need of an output filter. The output voltage is regulated by direct amplitude modulation. Unlike the standard interleaved converters, the proposed converter is robust to input voltage and operating duty cycle variations. Furthermore, equal current sharing is automatically achieved under all conditions, thus ensuring full utilisation of the output rectifiers for wide input and output ranges. The circuit achieves zero-voltage turnon for all primary switches and zero-current turnoff for the output rectifiers. An isolated dc-dc converter prototype with 5-V output voltage and 20-A output current has been built to verify the design.IEEE Transactions on Power Electronics 10/2007; · 4.08 Impact Factor
Conference Proceeding: Three level LLC series resonant DC/DC converter[show abstract] [hide abstract]
ABSTRACT: Paper presents a three level soft switching LLC series resonant DC/DC converter. ZVS is achieved for each main switch without any auxiliary circuit. Voltage stress of each main switch is half of input voltage. ZCS is achieved for rectifier diodes. Wide input/output range can be achieved under low frequency range because of two-stage resonance. Only one magnetic component is needed in this converter. Efficiency is higher in high line input, so this converter is fit for power products with hold up time requirement. The principle of operation and the characteristics of the new converter are analyzed and verified on a 500 V∼700 V input 54 V/10 A output experimental prototype, whose efficiency is 94.1% at rating condition.Applied Power Electronics Conference and Exposition, 2004. APEC '04. Nineteenth Annual IEEE; 02/2004
Conference Proceeding: Power architecture design with improved system efficiency, EMI and power density[show abstract] [hide abstract]
ABSTRACT: The optimized design of power architecture is discussed in this paper. The paper first discusses the asymmetrical interleaved multi-channel PFC technique and its benefits to system power density and the reduction of differential mode noise. A balance technique is then proposed to minimize the common mode noise of asymmetrical interleaved multi-channel PFC. Greatly reduced EMI leads to the size reduction of EMI filters. System power density is therefore improved. For DC/DC stage, a 1 MHz, LLC resonant converter with novel synchronous rectifier is proposed to reduce body diode conduction time. Both conduction loss and reverse recovery loss can be reduced. The whole system's efficiency, EMI and power density can be greatly improved by applying the techniques proposed in this paper.Power Electronics Specialists Conference, 2008. PESC 2008. IEEE; 07/2008