• Journal of Power Electronics
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• v.15 no.3
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• pp.652-659
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• 2015

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) $\approx$ f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.3
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• pp.145-150
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• 2013

A novel AC to DC PWM converters with unity input power factor are proposed to overcome the above shortcoming. The main function of these converters is to shape the input line current to force it exactly in phase with the input AC voltage. Therefore, the input power factor can be improved to near unity and the input current harmonics can be eliminated. In this paper, half-bridge converter with two active switches and two diodes are utilized for low-cost type UPS configuration. By having only two semiconductors in the current path at any time, losses can be reduced over the conventional boost topology. Also, this converter provides controllable dc-link voltage, high power factor, and low cost type converter by simple power circuits. Simulation results show that the proposed half-bridge converter/inverter control technique can be applied to single-phase low-cost type UPS systems successfully.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.694-700
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• 1998

A novel zero-voltage-transition (ZVT) isolated PWM boost converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[8]. A simple auxiliary circuit which includes only one active switch provides zero-voltage-switching (ZVS) condition to all semiconductor devices. (Two active switches are required for the previous ZVT converter) This leads to reduced cost and simplified control circuit comparing to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 kW, 100 KHz laboratory prototype.

• Journal of Power Electronics
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• v.2 no.4
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• pp.312-324
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• 2002

This paper presents a new PWM DC/DC converter with dual output power using single power stage, which has the isolation characteristics between each dual output. The proposed converter topology consists of two switches ($S_B$ and $S_F$) and only single secondary winding. Therefore, the proposed converter has better advantages of not only low cost and small size but also high power density because of using minimum components and devices compared with conventional methods which use multi winding transformers or several converters. The operating principle of the proposed converter topology, which includes the conventional auxiliary ZVT (Zero-Voltage-Transition) circuit to implement soft switching of the main switch, is illustrated in detail and the validity of the proposed converter is verified through several simulated and experimental results.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.111-115
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• 1997

This Paper is concerned on developing DC-DC converter using ZVS-FB-PWM Converter. The converter output is 28V and regulated by phase shift control methode. MOSFET is used by the main switching device and high frequency transfomer is made for operating at 300㎑ switching frequency. When the load vary widely, converter's ZVS characteristic is expressed by experiment result.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1029-1031
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• 2001

In this paper, we propose a three-phase soft-switching PWM-PFC converter and describe the circuit operations and the experimental results. The proposed converter is constructed by using a resonant network in parallel with the main switch of the conventional PWM converter. A new PWM-PFC converter achieves including the auxiliary switches without increasing their voltage and current stress.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.74-78
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• 1998

The shortcomings of zero-voltage-transition PWM converter is discussed and a new family of topologies of zero-voltage-transition PWM converter with soft-switched auxiliary switch is introduced. The experiments on a 290W boost converter and a 100W forward converter are carried out to prove the circuit. The efficiency increment of the new circuits are 2-5% comparing to hard switching circuits, and the switching noise is also greatly reduced.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.265-267
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• 1995

A voltage source PWM converter with battery charging and AC/DC power conversion ability is proposed in this paper. The proposed voltage source PWM converter is independently controlled by active and reactive components and implemented by DSP controller. In UPS application the mathematical model of the voltage source PWM converter has been derived. Finally, the performance of the voltage source converter is shown and discussed through experimental results.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.377-382
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• 2005

This paper presents two new circuit topologies of DC bus lineside active edge resonant snubber assisted soft-switching PWM full-bridge DC-DC converter acceptable for either utility AC 200V-rms or AC 400V-rms input voltage source. One topology of proposed DC-DC converters is composed of a typical voltage source-fed full-bridge high frequency PWM inverter using DC busline side series power semiconductor switching devices with the aid of a parallel capacitive lossless snubber. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off commutations and the total turn-off switching power losses of all active switches can be reduced for high-frequency switching action. It is proved that the more the switching frequency of full-bridge soft switching inverter increases, the more soft-switching PWM DC-DC converter with a hish frequency transformer link has remarkable advantages for its efficiency and power density as compared with the conventional hard-switching PWM inverter type DC-DC converter

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.529-534
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• 2017

In this paper, the implementation of proposed Automatic Load Balanced (ALB) PWM generation method is discussed. The conventional PWM generation method for cascade type H-bridge PWM converter causes the unbalance between each H-bridge converter, therefore the complex redundancy is required for the balancing of switching load of each converter, it consumes more computing power of controller. The ALB PWM method needs no additional switching redundancy for balancing, this paper discusses the implementation of ALB-PWM.