• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 전력전자학술대회 논문집
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• pp.333-334
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• 2014

Converters employing IGCTs usually require di/dt snubber and Over Voltage Protection (OVP) circuit for the protection of IGCTs and fast diodes. In these IGCT-based converters, conventional di/dt snubber and OVP circuit dissipates a significant amount of power loss. To reduce this loss of conventional di/dt snubber and OVP circuit, this paper proposes a flyback type snubber circuit with di/dt limiting characteristic for IGCT-based converters in medium voltage wind turbines. This flyback type snubber circuit simply consists of a flyback type transformer and diode. The proposed circuit reduces loss and simplifies conventional di/dt snubber by adopting the flyback type transformer. Loss analysis of conventional di/dt snubber and OVP circuit is performed for the 3-level NPC type back-to-back VSC supplied from grid voltage of 6.9kV. The proposed flyback type snubber circuit can save the loss of conventional snubber circuit in the 3L-NPC type back-to-back VSC in multi-MW MV wind turbine. The proposed snubber circuit has a fewer number of components and improved efficiency leading to a reliable and efficient wind turbine systems.

• 한국인터넷방송통신학회논문지
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• 제23권4호
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• pp.137-142
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• 2023

SMPS(Switched Mode Power Supply, 전력공급장치) 회로설계 시 특별한 고찰 없이 지나치기 쉬운 부분이 스너버(snubber) 회로이다. 그러나 스너버(snubber) 회로에 따른 SMPS의 성능저하 및 SET 전체에 미치는 영향은 결코 무시할 수 없다. 또한 스위칭시 피크치 전압과 전류로부터 소자를 보호하고 on/off 스위칭시 손실을 줄여주기 위하여 스위치 양단에 스너버(snubber) 회로를 부가해준다. 따라서 본 논문에서는 스너버(snubber) 회로에 대한 충분한 이해를 위해 이론적 해석 및 실제 회로설계 때 설계자가 응용할 수 있는 실험식을 정리하여, 스너버(snubber) 회로의 최적화를 도모하고자 한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.541-546
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• 1998

This paper proposes a new snubber circuit for multilevel inverter and converter. The snubber circuit makes use of Undeland snubber as basic snubber unit and can be regraded as a generalized Undeland snubber. The proposed snubber keeps such good features as fewer number of components, improved efficiency due to low loss snubber, capability of clamping overvoltage across main switching devices, and no unbalance problem of blocking voltage. Furthermore, the proposed concept of constructing a snubber circuit for multilevel inverter and converter can apply to any kind of basic snubber unit such as Holtz nondissipative snubber, McMurray efficient snubber, Lauritzen lossless snubber, etc which have been utilized for two-level inveter.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1928-1930
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• 1998

This paper proposes a new snubber circuit for multilevel inverter and converter. The snubber circuit makes use of Undeland snubber as basic snubber unit and can be regarded as a generalized Undeland snubber. The proposed snubber keeps such good features as fewer number of components, improved efficiency due to low loss snubber, capability of clamping overvoltage across main switching devices, and no unbalance problem of blocking voltage. Furthermore, the proposed concept of constructing a snubber circuit for multilevel inverter and converter can apply to any kind of basic snubber unit such as Holtz nondissipative snubber, McMurray efficient snubber, Lauritzen lossless snubber, etc which have been utilized for two-level inverter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.448-451
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• 2000

This paper proposed a snubber circuit for flying capacitor multilevel inverter and converter. The proposed snubber circuit makes use of Undeland snubber as basic snubber as basic snubber unit and has such an advantage of Undeland snubber used in the two-level inverter. Comparing conventional RCD/RLD snubber for multilevel in verter and converter the proposed snubber keeps such a good features as fewer number of components improved efficiency of system due to low loss snubber and reduction of voltage stress of main switching devices due to low overvoltage. Furthermore the proposed concept of constructing a snubber circuit for flying capacitor 3-level inverter and converter can apply to any level of them. In this paper the proposed snubber applies to three-level flying capacitor inverter and demonstrates its feature by computer simulation and experimental result.

• Smart Structures and Systems
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• 제25권3호
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• pp.385-391
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• 2020

In this paper, a new passive lossless snubber circuit with energy transfer capability is proposed. The proposed lossless snubber circuit provides Zero-Current Switching (ZCS) condition for turn-on instants and Zero-Voltage Switching (ZVS) condition for turn-off instants. In addition, its diodes operate under soft switching condition. Therefore, no significant switching losses occur in the converter. Since the energy of the snubber circuit is transferred to the output, there are no significant conduction losses. The proposed snubber circuit can be applied on isolated and non-isolated converters. To verify the operation of the snubber circuit, a boost converter using the proposed snubber is implemented at 70W. Also, the measured conducted Efficiency Electromagnetic Interference (EMI) of the proposed boost converter and conventional ones are presented which show the effects of proposed snubber on EMI reduction. The experimental results confirm the presented theoretical analysis.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권9호
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• pp.598-606
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• 2000

This paper proposes a new snubber circuit for 4-level inverter and converter. The snubber circuit makes use of Undeland snubber and McMurray efficient snubber as basic snubber unit and can be regarded as a generalized combined Undeland and McMurray efficient snubber. The proposed snubber keeps such good features as fewer number of components improved efficiency due to low snubber loss capability of clamping overvoltage across main switching devices and no unbalance problem of blocking voltage. Furthermore the proposed concept of constructing a snubber circuit for 4-level inverter and converter can apply to any level of converterand inverter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.124-130
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• 1997

The main switch of high-frequency boost converter may be failed because the high switching current or voltage can damage this switch. The high switching stress can be reduced by snubber circuit. In this paper, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter. The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The analysis for proposed circuit is presented, and the validity of the circuit is verified through simulation and experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 전력전자학술대회 논문집
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• pp.255-259
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• 1998

This paper is proposed three phase GTO PWM Inverter with energy recovery snubber circuit. The proposed energy recovery snubber circuit effective in reduction of the power loss in the Inverter system than asymmetry GTO snubber circuit.

• Journal of Advanced Marine Engineering and Technology
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• 제21권2호
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• pp.178-185
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• 1997

According to the wide - spread use of rectifier in electronic equipments, such problems as electronic components failures or equipment disorders have been occurred due to current harmonics. To overcome these problems, power factor correction circuits employing boost converter have been used. The high switching stress of boost converter can be reduced by snubber circuit. Recently, research activities in snubber circuits have been directed to energy recovery snubber for improving the efficiency of power converter. In this study, a new passive snubber circuit which can recover trapped snubber energy without added control is proposed for boost converter. The control of boost converter with proposed snubber is the same as the conventional one. In addition, the energy recovery circuit can be implemented with a few passive components. The circuit operation is confirmed through simulation.