• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.548-551
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• 2001

A zero-voltage transition (ZVT) PWM boost PFC converter using a transformer to recover the resonant energy into the input voltage is proposed. The proposed converter reduces turn-off switching loss of the auxiliary switch. The resonant current of the auxiliary circuit is optimally reduced by the feed-forwarded input voltage. Moreover, the resonant energy of the auxiliary circuit is recovered into the load and input voltages. In this paper, the modes of converter operation are explained and analyzed, design guidelines are given, and experimental results of 1.2kW, 200kHz prototype system are presented.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.235-238
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• 2003

This paper presents an ZVT(Zero Voltage Transition) Forward Converter using Primary Auxiliary Circuit operation. An auxiliary resonant circuit was added to the basic forward converter, implementing the fVT technique for the main switch. The switch employed by the auxiliary circuit operates under Zero-Current-Switching(ZCS) condition. The complete operating principle, simulation and experimental results are presented

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.3
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• pp.243-249
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• 2001

This paper proposes a full wave mode ZVT-PWM boost converter. The converter with the auxiliary switch in a full wave mode makes possible soft switching operation of all switches including the auxiliary switch whereas the auxiliary switch is turned off with hard switching in the conventional converter. Therefore, the proposed converter reduces the turn-off switching loss and switching noise of the auxiliary switch without additional passive and/or active elements and high power density system can be realized.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.942-945
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• 2001

This paper presents parallel operation of ZVT(Zero Voltage Transition) Full Bridge Converter with Dynamic Current Shared Inductor. In the conventional method, CT(Current Transformer) have been used to share the load current equally with converters. In this system, at parallel operation of ZVT Full Bridge Converter, dynamic current shared inductor divides the same current of unit converter and ZVT circuit aids to high efficiency. This method which is proposed to compare in the conventional method will do simple control circuit. To show the superiority of this converter is verified through the experiment with a 2kW, 50kHz prototype converter.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.295-298
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• 1999

In this paper, the diode bridge-type ZVT(Zero-Voltage Transition) inverter is proposed. It consists of one auxiliary switch, three resonant inductors and six blocking diodes. So, the advantage of the proposed topology is the reduction of the auxiliary switch. The topology of the proposed ZVT inverter is analyzed with a description of the control conditions based on the load current. Therefore, this paper two control algorithms were discussed. A variable resonant pattern control algorithm by using load current feedback and a resonant period control algorithm by using resonant inductor current feedback is proposed in order to achieve the ZVT switching condition in full control range and the reducing current spike main switches cause by reverse recovery problem.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.326-329
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• 2002

In this paper, a single-phase inverter using a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is presented. The current control algorithm is analyzed about how to design the circuit with auxiliary switch which can ZVT operation for the main power switch. The simulation and experimental results would be shown to verify the proposed current algorithm, because the main power switch is turn on with ZVT and the hi-directional inverter is operated.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.172-175
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• 2005

Recently international regulations governing the amount of harmonic currents(e.g IEC 61000-3-2) became mandatory and active Power factor correction (PFC) pre-regulator circuit became inevitable for the AC/DC converters. Among these topologies, the boost topology represents an optimum solution for a PFC pre-regulation in a high power application. This paper propose improved ZVT(Zero Voltage Transition) AC/DC PFC Boost using the average current control employing a soft-switching technique of the auxiliary switch with a minimum number of components. The conventional ZVT PFC Boost Converter has a disadvantage that the auxiliary switch turns off hard, which influences the overall efficiency and the EMI problem. In this paper, an improved ZVT PFC Boost converter using active snubber is proposed to minimize the switching loss of the auxiliary. The prototype of 100kHz, 640W system was implemented to show the improved performance.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.50-51
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• 2012

The paper presents a non-isolated bidirectional DC-DC converter for use in renewable power generation, battery, electric vehicles (EV) and small scale DC-UPS systems. In the propose design, the conventional interleaved operation of two-inductor boost structure is modified to accommodate bidirectional operation, and zero-voltage-transition (ZVT) is applied, where both the switch and the rectifier diode achieve soft condition without increasing their voltage and current stresses. The proposed converter has the merits of simple circuitry, reduced size, low cost and high efficiency. The operation principle of the converter is analyzed and verified. Also, simulation results of the proposed bidirectional dc-dc converter is shown.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.226-239
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• 2018

In this paper, design and control method ZVT Interleaved Bidirectional LDC(IB-LDC) for mild-hybrid electric vehicle is proposed. The IB-LDC is composed of interleaved buck and boost converters employing an auxiliary inductor and auxiliary capacitors to achieve zero-voltage-transition. Operating principle of IB-LDC according to operation mode is introduced and mathematically analyzed in buck and boost mode. Moreover, PFM and phase control are proposed to reduce circulating current for low power range. Passive components design such as main inductor, auxiliary inductor and capacitors is suggested, considering ZVT condition and maximizing efficiency. Furthermore, a 600W prototype of ZVT IB-LDC for MHEVs is built and tested to verify validity.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.262-265
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• 2003

In this paper, a new active snubber circuit that overcomes most of the drawbacks of the normal "zero voltage transition pulse width modulation" (ZVT-PWM) converter is proposed to contrive a new family of ZVT- PWM converter. A converter with the proposed snubber circuit can also operate at light load conditions. A design procedure of the proposed active snubber circuit is also presented. Additionally, at full output power in the proposed soft switching converter, the main switch loss is about 27[%] and the total circuit loss is about 36[%] of that in its counterpart hard switching converter, and so the overall efficiency, which is about 91[%] in the hard switching case, increases to about 97[%].