• Journal of Power Electronics
• /
• 제19권2호
• /
• pp.353-362
• /
• 2019

To address the problem of circulating current loss in the traditional zero-current switching (ZCS) full-bridge (FB) DC/DC converter, a ZCS FB DC/DC converter topology and modulation strategy is proposed in this paper. The strategy can achieve ZCS turn on and zero-voltage and zero-current switching (ZVZCS) turn off for the primary switches and realize ZVZCS turn on and zero-voltage switching (ZVS) turn off for the auxiliary switches. Moreover, its resonant circuit power is small. Compared with the traditional phase shift full-bridge converter, the new converter decreases circulating current loss and does not increase the current stress of the primary switches and the voltage stress of the rectifier diodes. The diodes turn off naturally when the current decreases to zero. Thus, neither reverse recovery current nor loss on diodes occurs. In this paper, we analyzed the operating principle, steady-state characteristics and soft-switching conditions and range of the converter in detail. A 740 V/1 kW, 100 kHz experimental prototype was established, verifying the effectiveness of the converter through experimental results.

• 전력전자학회논문지
• /
• 제26권5호
• /
• pp.372-375
• /
• 2021

A three-leg inverter-type isolated DC-DC Converter that can use 220 and 440 V grid input voltages is introduced. The secondary circuit structure of the proposed topology is center-tap, which is the same as the conventional phase-shifted full-bridge converter. However, the primary circuit structure is composed of a three-leg inverter structure and a transformer, in which two primary windings are connected in series. The proposed circuit structure has a wider input voltage range than the conventional phase-shifted full-bridge converter, and the circulating-current on the primary-side is reduced. In addition, the voltage stress at the secondary rectifier is greatly improved, and high efficiency can be achieved at a high input voltage by removing the snubber circuit added to the conventional converter. Prototype converters with input DC of 311 V, output of 622 V, and 50 V and 6 kW class specifications were designed and manufactured to verify the validity of the proposed topology; the experimental results are presented.

• 전력전자학회논문지
• /
• 제26권3호
• /
• pp.237-240
• /
• 2021

This research proposes a new rectifier circuit to reduce the circulating current of a phase-shifted full bridge converter. The proposed circuit is a structure in which the output inductor of the secondary rectifier circuit is changed to a coupled inductor in the phase-shifted full bridge with the existing center-tapped rectifier. The parts are rearranged after adding a diode. After applying the proposed circuit, the circulating current to the primary current of the transformer and the voltage stress of the rectifier diode on the secondary side of the transformer are reduced. Accordingly, the snubber loss of the rectifier is improved. By reducing the circulating current and snubber loss, the circuit achieves higher efficiency than conventional circuits. In this research, we present the structure of the proposed circuit, its strengths, and the analysis results from experiments. Furthermore, its effectiveness is verified through the experimental results of a prototype converter with an input of 300-400 V and an output of 50 V/1 kW.

• 전력전자학회논문지
• /
• 제25권6호
• /
• pp.469-476
• /
• 2020

This study presents the results of the research on power supplies for welding machine using MOSFET switches in high frequency switching for ease of design and use a 100 kHz switching frequency for high power density. The topology of the proposed power supplies for welding machine is ZVS-PWM full-bridge converter. The proposed converter is designed on a distributed transformer for ease of design and be used in a 100 kHz switching frequency for high power density. The problem of power imbalance of transformers occurring in parallel operation of transformers can be improved by applying common mode coupled inductor and the corresponding contents are experimented and verified in this paper to present conclusions.

• Wind and Structures
• /
• 제22권1호
• /
• pp.43-63
• /
• 2016

In conventional buffeting theory, it is assumed that the aerostatic coefficients along a bridge deck follow the strip assumption. The validity of this assumption is suspect for a cable-stayed bridge in the construction stages, due to the effect of significant aerodynamic interference from the pylon. This situation may be aggravated in skew winds. Therefore, the most adverse buffeting usually occurs when the wind is not normal to bridge axis, which indicates the invalidity of the traditional "cosine rule". In order to refine the studies of static wind load on the deck of cable-stayed bridge under skew wind during its most adverse construction stage, a full bridge 'aero-stiff' model technique was used to identify the aerostatic loads on each deck segment, in smooth oncoming flow, with various yaw angles. The results show that the shelter effect of the pylon may not be ignored, and can amplify the aerostatic loading on the bridge deck under skew winds ($10^{\circ}-30^{\circ}$) with certain wind attack angles, and consequently results in the "cosine rule" becoming invalid for the buffeting estimation of cable-stayed bridge during erection for these wind directions.

• Wind and Structures
• /
• 제16권4호
• /
• pp.373-391
• /
• 2013

This is the first of two companion papers that analyse ten years of on-site monitoring data for the Confederation Bridge to determine the validity of the original wind speeds and wind loads predicted in 1994 when the bridge was being designed. The check of the original design values is warranted because the design wind speed at the middle of Northumberland Strait was derived from data collected at shore-based weather stations, and the design wind loads were based on tests of section and full-aeroelastic models in the wind tunnel. This first paper uses wind, tilt, and acceleration monitoring data to determine the static and dynamic responses of the bridge, which are then used in the second paper to derive the static and dynamic wind loads. It is shown that the design ten-minute mean wind speed with a 100-year return period is 1.5% less than the 1994 design value, and that the bridge has been subjected to this design event once on November 7, 2001. The dynamic characteristics of the instrumented spans of the bridge including frequencies, mode shapes and damping are in good agreement with published values reported by others. The on-site monitoring data show bridge response to be that of turbulent buffeting which is consistent with the response predicted at the design stage.

• Wind and Structures
• /
• 제4권6호
• /
• pp.505-518
• /
• 2001

Shantou Bay Bridge is the first long-span suspension bridge in China. Because of its location near the Shantou Seaport and its exposure to high typhoon winds, wind-resistant studies are necessary to be made. In this paper, critical flutter wind speeds and buffeting responses of this bridge at its operation and main construction stages are investigated. The Buffeting Response Spectrum method is first briefly presented. Then the sectional model test is carried out to directly obtain the critical flutter wind speed and to identify the flutter derivatives, which are adopted for the later analysis of the buffeting responses using the Buffeting Response Spectrum method. Finally the aeroelastic full bridge model is tested to further investigate the dynamic effects of the bridge. The results from the tests and the computations indicate that the flutter and buffeting behaviors of the Shantou Bay Bridge are satisfied.

• 한국전자통신학회논문지
• /
• 제12권5호
• /
• pp.851-858
• /
• 2017

본 연구에서는 SPWM 구동방식의 단상 풀 브리지 인버터의 전압제어계를 설계하였다. 전압제어계는 단상 풀-브리지 인버터, 출력전압과 기준전압의 오차를 선형적으로 보상하기 위한 PI 제어기, 제어기 신호로부터 SPWM 방식을 이용하여 게이트 신호를 발생시키기 위한 PWM 구동회로, 인버터 출력 전압 파형을 정현 파형으로 필터링하기 위한 LC 필터로 구성하였다. 끝으로, EMTP-RV를 이용하여 PWM 구동방식을 기반으로 하는 단상 풀-브리지 인버터의 전압 제어계를 모델링하였고 수개의 기준전압에 대한 시뮬레이션 연구를 통해 출력전압이 정확하게 기준전압을 수렴하는 것을 확인함으로서 제어계 설계의 유효성을 확인할 수 있었다.

• 전기전자학회논문지
• /
• 제23권4호
• /
• pp.1208-1217
• /
• 2019

풀-브리지 서브모듈은 MMC의 단위 시스템으로서 서브모듈에 대한 수명예측은 HVDC 시스템의 유지 보수와 경제성 확보 관점에서 매우 중요하다. 그러나 일반적으로 부품의 종류, 개수, 결합 상태만을 고려하는 수명 예측은 대상 시스템의 구동상태를 고려하지 않는 일반화 된 결과로 실제 시스템의 수명과 크게 차이가 발생할 수 있다. 따라서 본 논문에서는 풀-브리지 서브모듈의 동작 특성을 반영하기 위한 목적으로 고장나무를 설계하고 기본 사상의 고장률에 MIL-HDBK-217F를 적용하여 풀-브리지 서브모듈의 수명을 예측한다. 기존의 부품고장률 분석과 제안된 고장나무 분석에 의한 기대 수명을 비교하고, 풀-브리지 서브모듈의 여유율 적용 여부에 따른 수명을 비교한다.

• 전력전자학회논문지
• /
• 제14권3호
• /
• pp.228-234
• /
• 2009

본 논문에서는 위상제어방식 풀브릿지 컨버터의 회로방식에 대한 전력손실과 전력변환 효율특성을 빠르고 효과적인 분석 방법에 대해 보고한 것이다. 위상제어방식 풀브릿지 컨버터의 회로 구성 소자 중에서 내부 기생저항만을 고려한 등가회로를 유도하고 이상적인 동작 파형을 이용하여 전류의 실효값과 전도손실을 유도하였다. 해석을 간단하게 하기 위해서 정상상태 결과로부터 코어 손실은 무시하였으며, 동기정류기 손실과 전도손실 만을 고려하였다. 해석결과의 타당성을 검토하기 위해서 시험용 위상제어방식 풀브릿지 컨버터를 구성하여 검증하였다. 입력전압 400V, 출력전압 12V, 최대전력 720W의 조건에서 실험결과와 해석결과와 비교적 잘 일치한다는 것을 본 논문에서 확인 하였다.