• 한국조명전기설비학회지:조명전기설비
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• 제9권4호
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• pp.62-70
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• 1995

Brushless DC Motor (BDCM) is widely used in the industry such as a variable speed motor in a compressor for room air conditioners, because the motor can be easily controlled and operated over a wide speed range. The system to drive BDCM needs encoder that senses rotor position. Gut in a certain application, the position sensor has to be avoided. In the paper, various position sensorless drive systems for BDCM are investigated and critically evaluated, so that the effective method of sensorless control can be selected. Out of these methods, the freewheeling diode current sensing has many advantages. For example, the simple starting procedure makes it possible to perform sensorless control even in low speed. So the hardware design for this method has been carried out and the system has been implemented using DSP. The experimental results verified that the freewheeling diode current sensing approach has advantages in starting procedure and low speed sensing.

• Journal of Power Electronics
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• 제15권6호
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• pp.1480-1488
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• 2015

In this paper, a revolutionary buck converter is proposed with soft-switching technology, which is realized by a coupled inductor. Both zero-voltage switching (ZVS) of main switch and zero-current switching (ZCS) of freewheeling diode are achieved at turn on and turn off without using any auxiliary circuits by the resonance between the parasitic capacitor and the coupled inductor. Furthermore, the peak voltages of the main switch and the peak current of the freewheeling diode are significantly reduced by the coupled inductor. As a result, the proposed converter has the advantages of simple circuit, convenient control, low consumption and so on. The detailed operation principles and steady-state analysis of the proposed ZVS-ZCS buck converter are presented, and detailed power loss analysis and some simulation results are also included. Finally, experimental results based on a 200-W prototype are provided to verify the theory and design of the proposed converter.

• 한국조명전기설비학회지:조명전기설비
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• 제10권6호
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• pp.54-61
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• 1996

본 논문에서는 기존에 제시된 영전압 준공진 buck dc-dc 컨버터를 시뮬레이션을 이용하여 분석하고, 이에서 발생하는 문제점을 분석하였다. 그리고 부하저항을 낮게 가변함에 따라 소자의 스트레스가 증가함을 확인하였다. 그 원인이 freewheeling다이오드의 기생 커채시턴스에 의한 전압상승에 의하여 발생함을 확인하고, 이를 개선할수 있는 영전압 스위칭 컨버터를 제시한다.

• ETRI Journal
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• 제35권4호
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• pp.603-609
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• 2013

In this paper, we present a 600-V reverse conducting insulated gate bipolar transistor (RC-IGBT) for soft and hard switching applications, such as general purpose inverters. The newly developed RC-IGBT uses the deep reactive-ion etching trench technology without the thin wafer process technology. Therefore, a freewheeling diode (FWD) is monolithically integrated in an IGBT chip. The proposed RC-IGBT operates as an IGBT in forward conducting mode and as an FWD in reverse conducting mode. Also, to avoid the destructive failure of the gate oxide under the surge current and abnormal conditions, a protective Zener diode is successfully integrated in the gate electrode without compromising the operation performance of the IGBT.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.485-486
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• 2015

This paper introduces the new 1200V $SPM^{(R)}$ (Smart Power Module), which is fully optimized and intelligent integrated IGBT inverter modules for up to 6kW motor drive applications. It utilizes newly developed NPT trench IGBT with the advanced STEALTHTM freewheeling diode, and built-in bootstrap diode. HVICs, multi-function LVIC, and built-in thermistor provide good reliable characteristics for the entire system. This module also takes technical advantage of DBC(Direct Bonded Copper) substrate for the better thermal performance. This paper provides an overall description of the newly developed 1200V/35A $SPM^{(R)}$ 2 product.

• 조명전기설비학회논문지
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• 제21권2호
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• pp.54-63
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• 2007

최근 저전압 대전류 출력 특성을 갖는 연료전지를 위한 새로운 발전시스템으로 주목받고 있다. 연료전지 발전시스템에서는 DC-DC 승압용 컨버터와 DC-AC 인버터가 필요하다. 그러므로 본 논문에서는 연료전지의 전압을 $380[V_{DC}]$로 승압하기 위한 절연형 DC-DC 컨버터와 단상 $220[V_{AC}]$로 변환하기 위한 LC필터를 가진 PWM 인버터로 구성된 전력변환장치를 제안하였다. 특히 제안한 고주파 절연형 ZVZCS PWM DC-DC 컨버터는 환류 다이오드를 포함한 탭부 인덕터 필터를 이용하여 순환 전류를 저감시켰으며, 스위치 및 변압기의 턴-온, 턴-오프시에 오버슈트 전압이나 과도현상이 발생하지 않는다. 그리고 넓은 출력 전압 조정에도 효율을 $93{\sim}97[%]$정도 얻을 수 있으며, 출력 부하전류의 변화에 대해 거의 일정한 출력 전압 특성을 가졌다.

• Journal of Electrical Engineering and Technology
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• 제12권6호
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• pp.2278-2288
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• 2017

Multilevel converter topologies are widely used in many applications. The cascaded H-bridge multilevel inverter (CHBMI), which is one of many multilevel converter topologies, has been introduced as a useful topology in high and medium power. However, it has a drawback to require a lot of switches. Therefore, the reliability of CHBMI is important factor for analyzing the performance. This paper presents a simple switch fault diagnosis method for single-phase CHBMI. There are two types of switch faults: open-fault and short-fault. In the open-fault, the body diode of faulty switch provides a freewheeling current path. However, when the short-fault occurs, the distortion of output current is different from that of the open-fault because it has an unavailable freewheeling current flow path due to a disconnection of fuse. The fault diagnosis method is based on the zero current time analysis according to zero-voltage switching states. Using the proposed method, it is possible to detect the location of faulty switch accurately. The PSIM simulation and experimental results show the effectiveness of proposed switch fault diagnosis method.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.251-255
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• 1997

The conventional high frequency phase-shifted full bridge dc/dc converter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current, RMS current stress, conduction losses of transformer and switching devices are increased. To alleviate this problem, this paper provides a circulating current free type high frequency soft switching phase-shifted full bridge (FB) dc/dc converter with energy recovery snubber (ERS) attached at the secondary side of transformer. The energy recovery snubber (ERS) adopted in this study is consisted of three fast recovery diode(Ds1, DS2, Ds3), two resonant capacitor (Cs1, Cs2)

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.36-38
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• 2001

A basic structure of 2500V-4500V reverse-conducting GCT (RC-GCT) is given in this paper. The punch-through type (PT) is adopted for narrow N-base with high resistivity so that the fast turn-off and low on-state voltage can be achieved. The photo mask design was made upon the both turn-off performance and solution of separation between GCT and integrated freewheeling diode (FWD) part. The turn-on and turn-off characteristics for reserve-conducting gate commutated thyristors (RC-GCTs) were investigated by ISE simulation. Additionally, the local carrier lifetime control by proton irradiation was adopted so as not only to obtain the reduction of turn-off losses of GCT but also to reach a soft reverse recovering characteristics of FWD

• 전력전자학회논문지
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• 제18권6호
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• pp.547-555
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• 2013

This paper proposes the interleaved buck converter using a soft switching auxiliary circuit. In this scheme, an auxiliary circuit is added to the conventional interleaved buck converter and used to achieve soft-switching conditions for both the main switch and freewheeling diode. In addition, the switch in the auxiliary circuit operates under soft-switching conditions. Also, according to the input to output conditions, the main switch achieved zero-current-transition(ZCT) or zero-current & zero-voltage-transition(ZCZVT) at turn on. Thus, the proposed interleaved buck converter provides a higher efficiency. The basic operations, in this paper, are discussed and design guidelines are presented. The usefulness of the proposed converter is verified on a 200kHz, 180W prototype converter.