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ABSTRACT: A parallel zero-voltage switching (ZVS) forward converter is proposed to achieve load current sharing, output ripple current cancellation and conversion efficiency improvement. Two forward converters are connected in parallel to achieve interleaved pulse width modulation operation. Thus, the ripple currents on the output side are partially cancelled on each other so that the size of output chokes and capacitor is reduced. Only two switches are used in the proposed converter instead of four switches in the conventional parallel ZVS forward converter. Therefore the proposed converter has less power switching devices. An active snubber is connected between two power transformers to absorb the energy stored in the leakage and magnetising inductances of transformers, to limit voltage stresses across switches and to realise the ZVS turn-on of all switches. Thus, the conversion efficiency is improved by the soft-switching operation of switching devices. Finally, the performance of the proposed converter is evaluated on a 480 W (24 V/20 A) laboratory prototype.
IET Power Electronics 03/2011; · 1.62 Impact Factor
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ABSTRACT: A soft switching active-clamp dual-series resonant converter is proposed here. Two small transformers are used in the proposed topology to provide more load power. An active-clamp circuit is used to absorb the energy stored in the leakage inductor of transformer, to clamp voltage stresses across switches and to realise the zero-voltage switching turn-on of switches in order to alleviate the switching losses. In order to remove the reverse-recovery problem on output diodes, the zero-current switching turn-off is realised by choosing the proper angle frequency on the secondary side. Analysis of mode operation, design considerations and experimental results of the proposed zero-voltage zero-current switching (ZVZCS) converter are described in detail. Finally, a 200 W ZVZCS prototype treated under V <sub>in</sub>=48=V, V <sub>o</sub>=200=V is implemented to verify the practicability of the proposed converter.
IET Power Electronics 10/2010; · 1.62 Impact Factor
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ABSTRACT: This study presents a reduced switch dual-converter to implement the features of zero-voltage switching (ZVS), load current sharing, high output current and low output ripple current. There are two converter modules in the proposed converter. These two modules share the same power switches and provide the balance load current. The active-clamping circuit is used to realise the ZVS turn-on such that the switching losses on power switches are reduced. The current output rectifier is adopted in the output side to realise the higher output current with reduced ripple current such that the sizes of the output chokes and capacitor are reduced. Compared with the conventional ZVS parallel-connected converter with four power switches, only two switches are used in the proposed converter to accomplish parallel operation. Thus, the proposed converter has less circuit components. Finally, the experimental results based on a laboratory prototype (12 V/50 A) are provided to demonstrate the effectiveness of the proposed converter.
IET Power Electronics 08/2010; · 1.62 Impact Factor
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ABSTRACT: A new zero voltage switching (ZVS) converter with a double-ended rectifier is presented to reduce switching losses on power semiconductors, decrease voltage stresses on rectifier diodes and achieve bidirectional power delivery to output load. A buck-boost type of active snubber is connected in parallel with the primary side of a transformer to recycle the energy stored in transformer leakage and magnetising inductors and to limit voltage stress on the main switch. During the transition interval, the transformer leakage inductor and the output capacitor of power MOSFET are resonant to realise the ZVS turn-on of the switch. Finally, the experimental results were given to demonstrate the circuit performance and to verify the feasibility of the proposed converter.
IET Power Electronics 04/2010; · 1.62 Impact Factor
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ABSTRACT: The system analysis, circuit implementation and design consideration of interleaved bi-flyback converter with zero voltage switching (ZVS) are presented. To reduce the ripple current on the input and output capacitors and decrease the current stress on the transformer secondary windings, two modules with interleaved pulse-width modulation (PWM) are connected in parallel at the input and output sides. Thus, the transformer copper losses and the conduction losses on the output diodes are reduced. Active snubber is connected in parallel with the main switch to limit the voltage spike because of the transformer leakage inductance when main switch is turned off. All power switches are turned on at ZVS during the commutation stage. Thus, the switching losses and thermal stresses of the semiconductors are reduced. Finally, experiments based on a 720 W (24 V 30 A) prototype are provided to verify the theoretical analysis and the effectiveness of the proposed converter.
IET Power Electronics 04/2010; · 1.62 Impact Factor
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ABSTRACT: A parallel zero voltage switching (ZVS) forward converter with half-bridge topology is presented in this paper. Two converter modules are connected in parallel in the output side to share the load current. In the primary side, two converter modules use the same power switches so that the semiconductor devices are reduced in the proposed converter compared with the conventional interleaved half-bridge converter. The asymmetrical pulse-width modulation (APWM) is used to regulate the output voltage and realize the ZVS turn-on of switches at the transition interval. The voltage stress of switches is clamped at the input source voltage. The system analysis, operation principle and design consideration of the proposed converter are presented. Finally experimental results based on a laboratory prototype are provided to verify the effectiveness of the proposed converter.
Power Electronics and Drive Systems, 2009. PEDS 2009. International Conference on; 12/2009
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ABSTRACT: A soft-switching converter with dual resonant structures is presented in this paper. The dual resonant tanks are composed by the leakage inductors and resonant capacitors to achieve zero-current-switching (ZCS) turn-off mechanism for diodes at the secondary side of transformer. Moreover, the voltage stresses of power switches are clamped by the active clamp circuit at the primary side of transformer. The active clamp circuit is not only absorbed the energy stored in the leakage inductor but also create zero-voltage-switching (ZVS) turn-on feature for power switches. Hence, the reverse-recovery problem can be eliminated. The operational principles, design consideration and realization are discussed. Finally, experimental results from a 400 W prototype are presented to confirm the effectiveness of the proposed converter.
Power Electronics and Drive Systems, 2009. PEDS 2009. International Conference on; 12/2009
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ABSTRACT: This study presents an integrated sepic-forward converter for photovoltaic (PV)-based light emitting diode (LED) lighting system. In the proposed converter, the sepic converter is used to deliver the solar energy via PV cell modules to battery bank in charging mode during the daytime. During the nighttime, the soft switching forward converter is adopted to drive LED lighting system in discharging mode. Power switches of sepic and soft switching forward converters are integrated to reduce the component count and the synchronous switch technique is used in the circuit to reduce the conduction losses. Thus, the smaller size, lighter weight and higher efficiency can be achieved in the proposed converter. Finally, experimental results, taken from a laboratory prototype rated at 100 W, are presented to verify the effectiveness of the proposed converter.
IET Power Electronics 12/2009; · 1.62 Impact Factor
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ABSTRACT: This paper presents an interleaved converter with the feature of zero voltage switching (ZVS). Two buck-type converters connected in parallel have the same switching devices and operate under the interleaved pulse-width modulation (PWM). Thus the output ripple current in the proposed circuit is less than that in the conventional forward converter. Thus the size of the output choke and capacitor is reduced. Only two switches are used in the proposed circuit instead of four switches in the conventional parallel ZVS converter. Therefore the circuit components in the proposed converter are reduced. ZVS turn-on is achieved during the commutation stage of two complementary switches such that the switching losses thermal stresses on the semiconductors are reduced. Experiments based on a 330 W prototype are provided to verify the theoretical analysis and the effectiveness of the proposed converter.
IET Power Electronics 10/2009; · 1.62 Impact Factor
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ABSTRACT: A dual resonant converter using active clamp circuit is presented in this paper. The active clamp circuit is employed to limit the voltage stress and create zero-voltage-switching (ZVS) turn-on feature for power switches. Moreover, the dual resonant tanks are composed by the leakage inductors and resonant capacitors to achieve zero-current-switching (ZCS) turn-off mechanism for diodes at the secondary side of transformer. Hence, the reverse-recovery problem can be eliminated. The operational principles, design consideration and realization are discussed. Finally, experimental results from a 400W prototype are presented to confirm the effectiveness of the proposed converter.
Industrial Electronics, 2009. ISIE 2009. IEEE International Symposium on; 08/2009
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ABSTRACT: An integrated converter with active clamping technique to achieve zero voltage switching (ZVS) is presented. In the proposed converter, the flyback and zeta topologies are used in the input and output sides to achieve the following features: to share the power switches in the transformer primary side, to achieve the partial magnetising flux reset and to share the load current. The input power is delivered to the load by the interleaved operation. The active clamping circuit, besides contributing to reduce commutation losses, resets the energy stored in the leakage inductances of both converters and the magnetising inductance of the zeta converter. The magnetising inductance of the flyback converter is reset by the load. Based on the resonance with the resonant inductance and output capacitance of switches, switches can be turned on at ZVS during the transition interval. Experimental results, taken from a laboratory prototype rated at 360 W, input voltage of 200 V, output voltage of 12 V and switching frequency of 125 kHz, are presented to demonstrate the converter performance.
IET Power Electronics 08/2009; · 1.62 Impact Factor
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ABSTRACT: The system analysis and the circuit implementation of a zero voltage switching (ZVS) bi-forward converter is presented here. Two forward converters are adopted in the circuit with the active clamp technique to achieve interleaved PWM operation and load current sharing. Only two switches are used in the proposed converter instead of the four switches in the conventional parallel ZVS converter. Thus, the circuit components and conduction losses are reduced in the proposed converter. In the proposed circuit, the PWM signals of two switches are complementary to each other with a small delay time in order to realise the ZVS turn-on of the switches at the transition interval. Thus, the switching losses and thermal stresses of semiconductors are reduced since the interleaved PWM scheme is used to control two forward converters such that the output ripple currents are partially cancelled out. The sizes of the output chokes and capacitor are reduced. Experiments based on a 300 W prototype are provided to verify the theoretical analysis and the effectiveness of the proposed converter.
IET Power Electronics 02/2009; · 1.62 Impact Factor
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ABSTRACT: A soft-switching pulse-width modulation (PWM) converter with parallel connection to realise the zero voltage switching (ZVS) and achieve load current sharing is presented. The leakage inductance of the transformer and output capacitances of power switches are adopted to realise the resonance at the transition interval of switches such that the ZVS turn-on can be achieved. The energy stored in the transformer leakage and magnetising inductances can be released to limit the peak voltage stress of switching devices. To reduce the ripple current on the output capacitor and reduce the current stress on the secondary windings of the transformer, the parallel-connected circuit with an interleaved PWM scheme is used at the output side to share the load current and reduce the output ripple current. The operation principles, steady-state analysis and design equations of the proposed converter are provided in detail. Finally, experiments based on a 1 kW (12 V/84 A) prototype are provided to verify the theoretical analysis and the effectiveness of the proposed converter.
IET Power Electronics 02/2009; · 1.62 Impact Factor
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ABSTRACT: A soft switching bi-flyback converter is presented. Two identical flyback converters are used in the proposed circuit to share the load current. Thus, the transformer copper losses and the conduction losses on the output diodes are reduced. An active snubber is adopted to reduce the voltage spike and realise the ZVS turn-on of switches at the transition interval. Thus, the switching losses and thermal stresses of the semiconductors are reduced. Experiments are provided to verify the effectiveness of the proposed converter.
Electronics Letters 11/2008; · 0.96 Impact Factor
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ABSTRACT: An interleaved pulse-width modulation (PWM) converter with less power switches is presented in this paper. The buck type of active clamp circuit is used to recycle the energy stored in the leakage inductor of a transformer. The zero voltage switching (ZVS) turn-on of power switches is realized by the resonance during the transition interval of power switches. At the secondary side of transformers, two full-wave rectifiers with dual-output configuration are connected in parallel to reduce the current stresses of the secondary windings of transformers. In the proposed converter, power switches can accomplish two functions of the interleaved PWM modulation and active clamp feature at the same time. Therefore, the circuit components in the proposed converter are less than that of the conventional interleaved ZVS forward converter. The operation principle and system analysis of the proposed converter are provided in detail. Experimental results for a 280 W prototype operated at 100 kHz are provided to demonstrate the effectiveness of the proposed converter. Copyright © 2008 John Wiley & Sons, Ltd.
International Journal of Circuit Theory and Applications 11/2008; 38(2):179 - 197. · 1.63 Impact Factor
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ABSTRACT: The zero voltage switching (ZVS) boost converter with high-voltage gain is presented to overcome the limit of conventional boost converter with narrow turn-off period. Compared with the conventional boost converter, the adopted converter has wide turn-off period so that the higher output voltage can be achieved. The boost type of active clamp is used to limit the voltage stress of power switch. The resonance based on the output capacitance of power switch and resonant inductance will make the power switches to turn on at ZVS. The circuit configuration, principle operation, system analysis and design consideration of the adopted converter are presented. Finally, experiments conducted on a laboratory prototype rated at 240 W are presented to verify the effectiveness of the adopted converter.
IET Power Electronics 10/2008; · 1.62 Impact Factor
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ABSTRACT: System analysis of a bidirectional DC-DC converter for a fuel cell electric vehicle driving system is presented. The proposed converter is based on a zero voltage switching (ZVS) half-bridge converter with centre-tapped rectifier at the secondary side of the transformer. The asymmetrical pulse-width modulation is used in the converter to achieve ZVS feature of power switches and to regulate the output voltage at the desired value. The proposed converter has the advantages of high efficiency, low circuit components and simple circuit configuration. The operating principle and the system analysis are described and discussed in detail. Finally, the experimental results for the proposed converter are provided to verify the theoretical analysis.
IET Power Electronics 10/2008; · 1.62 Impact Factor
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ABSTRACT: A bidirectional ZVS DC-DC converter with active clamp topology is proposed. The proposed converter is based on the forward converter with center-tapped rectifier at the transformer secondary side. Active clamp topology is used in the forward converter to achieve ZVS feature of power switches and to regulate the output voltage at the desired value. The proposed converter has the advantages of high efficiency and simple circuit configuration. The operating principle, system analysis and design example are described and discussed in detail. Finally, the experimental results of the proposed converter are provided to verify the theoretical analysis.
Industrial Electronics and Applications, 2008. ICIEA 2008. 3rd IEEE Conference on; 07/2008
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ABSTRACT: This paper presents the system analysis and implementation of a soft switching Sepic-Cuk converter to achieve zero voltage switching (ZVS). In the proposed converter, the Sepic and Cuk topologies are combined together in the output side. The features of the proposed converter are to reduce the circuit components (share the power components in the transformer primary side) and to share the load current. Active snubber is connected in parallel with the primary side of transformer to release the energy stored in the leakage inductor of transformer and to limit the peak voltage stress of switching devices when the main switch is turned off. The active snubber can achieve ZVS turn-on for power switches. Experimental results, taken from a laboratory prototype rated at 300W, are presented to verify the effectiveness of the proposed converter. I. Introduction Modern
Industrial Electronics and Applications, 2008. ICIEA 2008. 3rd IEEE Conference on; 07/2008
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ABSTRACT: This paper presents the system analysis and circuit implementation of a soft switching converter based on buck-flyback topology to have a large voltage step-down between the output and input sides. Compared with the conventional buck converter, the proposed converter has wide turn-on period so that the lower output voltage can be achieved. An active snubber circuit is connected in parallel with the main switch to achieve zero voltage switching (ZVS). The resonance is based on the output capacitance of power switch and resonant inductance at the transition interval between the main and auxiliary switches. Therefore, the turn-on switching losses of power switch are reduced. The circuit configuration, system analysis, and design consideration of the proposed converter are presented in detail. Finally, experimental results based on a laboratory prototype with 240 W rated power are provided to verify the effectiveness of the proposed converter.
Industrial Electronics and Applications, 2008. ICIEA 2008. 3rd IEEE Conference on; 07/2008
