• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.541-543
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• 1997

In this paper, a proposed resonant PWM switching technique makes the boost AC/DC converter to high input power factor and less switching loss. Also, the switching control scheme is used which minimize harmonic components employing novel PWM technique. In addition, an employment of resonant circuit for switching makes zero current switching(ZCS) and zero voltage switching(ZVS) for control switches without switching losses. The result shows that high power factor is still for varying load and switching loss is very low.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.8
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• pp.455-460
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• 1999

A novel zero-voltage-transition (ZVT) PWM converter for switched reluctance motor (SRM) drives is proposed. A simple auxiliary circuit which consists of one active switch, one resonant inductor, and three diodes provides ZVS condition to all main switches and diodes allowing high frequency operation of the converter with high efficiency. The auxiliary circuit is placed in parallel with the main power flow path and thus it handles only a small fraction of the main power. So, the power rating of the auxiliary circuit can be very small (about 30% of main power). So, the auxiliary circuit can be realized with small power rating and low cost. Operation, features and characteristics of the proposed converter are illustrated and verified on a 1.5 kW, 50 kHz IGBT based (a MOSFET for the auxiliary with) experimental circuit.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.49-55
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• 2003

This paper presents a novel three-phase current-fed Pulse Width Modulation converter with switched capacitor type resonant DC link commutation circuit operating PWM pattern strategy under a design consideration of low-pass filter, which can operate on the basis of the principle of zero current soft switching commutation. In the first place, the steady state operating principle of this converter with a new resonant DC link snubber circuit is described in connection with the equivalent operation circuit, together with the practical design procedure of the switched-capacitor type resonant DC link circuit is discussed from a theoretical viewpoint on the basis of a design example for high-power applications. The actively delayed time correction method to compensate distorted currents due to a relatively long resonant commutation time is newly implemented in the open loop control scheme so as to acquire the new optimum PWM pattern. Finally, the experiment of set-up in laboratory system of this converter is concretely demonstrated herein to confirm a zero current soft-switching commutation of this converter. The comparative evaluations between current-fed hard switching PWM and soft-switching PWM converters are carried out from a viewpoint of their PWM converter characteristics.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.4
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• pp.60-67
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• 2008

This paper presents a new full-bridge soft switching PWM DC-DC converter circuit topology that adding two switcher, two lossless snubber quasi-resonance capacity, two diode to power source for general welding machine. This half bridge soft switching Is low voltage hight current output that first coil current is smaller than second coil current in high frequency transformer can be obtained with decreasing path loss in conventional DC bus line switcher. As it operate ZCS/ZVS in full range, high frequency, high efficiency and high output are implemented at low voltage and high DC current switching power supplies. All of this items are got from simulation and the result of experiment. If make up for the weak points of this proposed circuit, it will be used more easily for next generation TIG, MIG and MAG type of arc-welding machine.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.3
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• pp.209-214
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• 2000

In this paper, we propose a FB ZVT(full bridge zero voltage transition) PWM OC~OC converter which uses a a saturable reactor, instead of two additional switches, to achieve zero voltage switching. The conventional h high frequency phase shifted FB ZVT PWM OC-OC converter has a disadvantage that a circulating current f flows through high frequency transformer and switching devices during the free-wheeling interval. Due to this c circulating current, conduction loss increases. In order to reduce such the loss as this, we propose circuit of r reducing conduction loss at the secondary side of transformer. The operation principles are explained in detail a and the several interesting simulations and experimental results verify the validity of the proposed circuit.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.129-131
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• 2006

This paper presents a new ZVS-PWM high frequency inverter. The ZVS operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. The operating principle and the operating characteristics of the new high frequency circuit treated here are illustrated and evaluated on the basis of simulation results. It was examined that the complete soft switching operation can be achieved even for low power setting ranges by introducing the high frequency dual duty cycle control scheme. In the proposed high frequency inverter treated here, the dual mode pulse modulation control strategy of the asymmetrical PWM in the higher power setting ranges and the lower power setting ones, the output power of this high frequency inverter could introduce in order to extend soft switching operation ranges. Dual duty cycle is used to provide a wide range of output power regulation that is important in many high frequency inverter applications. It is more suitable for induction heating applications the operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.2
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• pp.19-28
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• 1997

A simple AC complex circuit analysis for LCL type series resonant converter with phase shift control is proposed. Based on these analyses, a set of characteristic curves which allows a optimal design procedure for this converter is shown, without increasing the volt-ampere rating of tank circuit. Especially, inverter output peak current can be minimized in both full load and partial load conditions. The presented design considerations can make the load range wide from full loads to light loads achieving turn-on with zero voltage switching (ZVS) operation. The simulation and experimental results show the effectiveness of the proposed design algorithms.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.341-345
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• 2004

A high efficiency and low device stress voltage and current clamping BVS PWM asymmetrical half bridge converter is proposed in this paper. To achieve the ZVS of power switches along the wide load range, the transformer leakage inductor $L_{Ikg}$ is increased. Then, to solve the problem related to ringing in the secondary rectifier caused by the resonance between $L_{Ikg}$ and rectifier junction capacitors, the proposed converter employs a voltage and current clamping cell, which helps voltages and currents of rectifier diodes to be clamped at the output voltage and output current, respectively. Therefore, no RC-snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. In addition, since all energy stored in $L_{Ikg}$ is transferred to the output side, the circulating energy problem can be effectively solved and duty loss does net exist. The operational principle, theoretical analysis, and design considerations are presented. To confirm the operation, validity, and features of the proposed circuit, experimental results from a 425W, 385-170Vdc prototype are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.5
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• pp.518-525
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• 2005

The paper proposes a novel ZVZCS PWM converter. It enables the main switch to be turned on/off with both zero voltage and zero current, the auxiliary switch to be turned on/off with ZCS, the rectifier diode to be turned on/off with ZVS. Moreover, this proposed soft switching technique is suitable for not only minority carrier device but also majority carrier semiconductor device. Since auxiliary resonant circuit of the proposed boost converter is placed out of the main power path, therefore, there are no voltage and current stresses on the main switch and diode. The operation of the proposed boost converter is explained and analyzed theoretical and experimentally, from a prototype operating at 100KHz.

• Journal of Power Electronics
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• v.18 no.2
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• pp.375-382
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• 2018

A novel active controlled primary current cutting-off zero-voltage and zero-current switching (ZVZCS) PWM three-level dc-dc converter (TLC) is proposed in this paper. The proposed converter has some attractive advantages. The OFF voltage on the primary switches is only Vin/2 due to the series connected structure. The leading-leg switches can obtain zero-voltage switching (ZVS), and the lagging-leg switches can achieve zero-current switching (ZCS) in a wide load range. Two MOSFETs, referred to as cutting-off MOSFETs, with an ultra-low on-state resistance are used as active controlled primary current cutting-off components, and the added conduction loss can be neglected. The added MOSFETs are switched ON and OFF with ZCS that is irrelevant to the load current. Thus, the auxiliary switching loss can be significantly minimized. In addition, these MOSFETs are not series connected in the circuit loop of the dc input bus bar and the primary switches, which results in a low parasitic inductance. The operation principle and some relevant analyses are provided, and a 6-kW laboratory prototype is built to verify the proposed converter.