• Proceedings of the KIPE Conference
• /
• 1999.07a
• /
• pp.319-322
• /
• 1999

This paper presents a novel single-stage Power Factor Corrected(PFC) AC/DC forward converter with semi-automatic current shaping in order to achieve the unity power factor and an isolated output. Since the proposed circuit is combined a boost converter used for PFCs with a forward converter used for DC to DC conversion, the over-all size of system could be reduced. And thanks to the zero voltage switching(ZVS) in both switches, the voltage stress can be reduced considerably. A simple auxiliary circuit adopted into the secondary of transformer is composed of lossless components for reducing surge voltage. A prototype which has tow IGBT(Insulated Gate Bypolar Transistor) modules as switching device is manufactured to evaluate the proposed topology. The characteristics of the proposed circuit are tested, and the validity is verified by experimental results.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.933-934
• /
• 2006

본 논문에서는 새로운 양방향 ZVS PWM Sepic/Zeta 컨버터를 제안한다. 제안한 컨버터는 PWM 제어가능한 컨버터로서 입력과 출력전압의 극성이 같은 비반전 컨버터의 특징을 지니며 DC 전압의 전달함수가 양방향 모두 M=D/(1-D)로 동일하다. 또한 각방향으로 전력전달시 다이오드와 병렬로 연결된 MOSFET가 다이오드의 'ON'시 동시에 'ON'되어 Sychronous Rectifier로 동작하므로 도통손을 저감하였으며, Auxiliary Resonant Commutated Pole를 사용하여 저감된 스위칭 손실을 갖는 특성을 지니고 있다. 또한 Transformer 버전이 존재하므로 입력과 출력사잉에 전기적 절연을 필요로 하는 실제응용에 유용하게 사용할 수 있다.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2076-2084
• /
• 2016

In this paper, a novel scheme to eliminate common-mode voltage (CMV) is proposed for three-level neutral-point clamped (NPC) inverters. In the proposed scheme, a low-power full-bridge converter is utilized to produce compensatory voltage for CMV, which is injected into an NPC inverter through a single-phase four-winding transformer. With the proposed circuit, the power range for applications is not limited, and the maximum modulation index of the inverter is not reduced. These features are suitable for high-power medium-voltage machine drives. The effectiveness of the proposed method is verified by simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.6 no.1
• /
• pp.21-26
• /
• 2001

This paper proposes a new double-connected 3-phase voltage source inverter with improved output voltage waveform. An auxiliary single-phase inverter injects a ripple voltage into the double-connected inverter to converter 12-step operation to 36-step operation. The KVA rating of the output phase-shifting transformer is reduced by employing a harmonic canceling reactor. The whole rectifier-inverter system including the proposed technique is introduced, and the experimental results are provided.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.549-551
• /
• 2005

Bidirectional DC/DC converters allows transfer of power between two dc sources, in either direction. Due to their ability to reverse the direction of flow of power, they are being increasingly used in many applications such as battery charger/dischargers, dc uninterruptible power supplies, electrical vehicle motor drives, aerospace power systems, telecom power supplies, etc. This paper proposes a new bidirectional Sepic/zeta converter. It has low swicthing loss and low conduction loss due to auxiliary communicated circuit and synchronous rectifier operation, respectively. Because of positive and buck/boost-like DC voltage transfer function(M=D/1-D), the proposed converter is very desirable for use in distributed power system . The proposed converter also has both transformerless version and transformer one.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1990-1992
• /
• 2000

Isolated phase bus is, as a special bus which allows large current from a generator to main transformer, composed of main conductor, enclosure and auxiliary equipments such as insulating bellows, bus elbows, support insulator, etc. To develop this kind of high power devices, it is required to secure the technique of selection of conducting and insulating materials, basic arrangement skills, and analysis on eddy current which causes temperature increase in enclosures. By the way, these techniques are based on the analysis of electromagnetic phenomena for high voltage and large current. In this study, an electromagnetic field analysis program is developed and applied to the isolated phase bus. which could be the basic numerical method for the analysis design and modifying isolated phase bus.

• Proceedings of the IEEK Conference
• /
• 2001.06e
• /
• pp.245-248
• /
• 2001

This paper is indicating the problems, which are the conduction loss on the high frequency transformer, the protection of rectification diode as the snubber loss and the stress of switching main devices, as be made high current and high speed in the phase-shift switching full-bridge DC-DC converter is used the power supply’s main circuit of high capacity. To improve those problems, in this paper, it is proposed that is the resonant circuit auxiliary can be reduced conduction losses and stabilized output control. And, it is constructed prototype of the power supply as the result of computer simulations.

• Proceedings of the KIEE Conference
• /
• 1996.07b
• /
• pp.1304-1306
• /
• 1996

A regenerative signal amplifying gate driver of self-excited electronic ballast is presented. It can be used for high pressure sodium (HPS) lamp without auxiliary external ignitor. Since the HPS lamp requires very high ignition voltage at start up, the resonant frequency of the circuit must be increased to obtain high voltage oscillations in spite of relatively small resonant current. The presented gate driver amplifies the current of gate drive transformer and raises the gate-source voltage Quickly to turn on the MOSFET switches. Hence, the resonant frequency can be increased more than 100kHz. The HPS lamp used in the simulation and experiment has the rating of 400W input power at 220V input ac voltage source. The experiments show that the resonant frequency is above 150kHz at start up.

• Proceedings of the KIEE Conference
• /
• 2009.04b
• /
• pp.156-160
• /
• 2009

This paper presents the interleaved active-clamping ZVS(Zero Voltage Switching) forward converter, which is mainly composed of two active-clamping forward converters. Only two switches are required, and each one is the auxiliary switch for the other. The circuit complexity and cost are thus reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve ZVS during the dead times. The duty cycles are not limited to be equal and within 50%. The complementary switching and the resulted interleaved output inductor currents diminish the current ripple in output capacitors. Accordingly, the smaller output chokes and capacitors lower the converter volume and increase the power density. Detailed analysis and design of this new interleaved active-clamping forward converter are described.

• Proceedings of the KIPE Conference
• /
• 2001.07a
• /
• pp.608-611
• /
• 2001

This paper is indicating the problems, which are the conduction loss on the high frequency transformer, the protection of rectification diode as the snubber loss and the stress of switching main devices, as be made high current and high speed in the phase-shift switching full-bridge DC-DC converter is used the power supply's main circuit of high capacity. In this paper, to improve those problems, it is proposed that is the resonant circuit auxiliary can be reduced conduction losses and stabilized output control. And, it is constructed prototype of the power supply as the result of computer simulations.