• Journal of Power Electronics
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• 제18권4호
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• pp.975-984
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• 2018

This work presents a high efficiency phase shifted full bridge (PSFB) DC-DC converter for use in the second stage of a battery charger for neighborhood electrical vehicle (EV) applications. In the design of the converter, Lithium-ion battery cells are preferred due to their high voltage and current rates, which provide a high power density. This requires wide range output voltage regulation for PSFB converter operation. In addition, the battery charger works with a light load when the battery charge voltage reaches its maximum value. The soft switching of the PSFB converter depends on the dead time optimization and load condition. As a result, the converter has to work with soft switching at a wide range output voltage and under light conditions to reach high efficiency. The operation principles of the PSFB converter for the continuous current mode (CCM) and the discontinuous current mode (DCM) are defined. The performance of the PSFB converter is analyzed in detail based on wide range output voltage and load conditions in terms of high efficiency. In order to validate performance analysis, a prototype is built with 42-54 V / 15 A output values at a 200 kHz switching frequency. The measured maximum efficiency values are obtained as 94.4% and 76.6% at full and at 2% load conditions, respectively.

• 전력전자학회논문지
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• 제10권5호
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• pp.443-449
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• 2005

본 논문에서는 연료 전지 시스템을 위한 Z-소스 인버터로 구성된 병렬 운전 시스템을 제시 하였다. PWM 방식으로는 Carrier phase shifted SPWM을 적용하였으며 이 방식은 출력 전류의 고조파 성분을 줄일 수 있는 장점을 갖는다. 그러나 이 기법을 Z-소스 인버터로 구성된 병렬 운전 시스템에 적용하는 경우 추가적으로 순환 전류를 발생한다. Z-소스 인버터로 구성된 병렬 운전 시스템이 동작 시 발생하는 순환 전류를 분석하고 순환 전류를 감소시키며, 부하전류에 낮은 고조파 성분을 가질 수 있도록 순환 전류 리액터를 사용하였다. 이에 대한 적합성을 시뮬레이션과 실험을 통해 입증하였다.

• 전력전자학회논문지
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• 제6권2호
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• pp.209-216
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• 2001

종래의 위상전이 영저낮 스위칭 풀-브리지 DC/DC 컨버터와 비슷하게 영전압 스위칭 3레벨 DC/DC 컨버터의 동작 모드 및 파형에서도 순환모드 구간동안 흐르는 순환전류에 EK라 스위칭소자 및 변압기에서의 도통손실이 증가하는 단점을 갖고 있다. 따라서, 본 논문에서는 스위칭전원의 효율개선 및 스위칭 주파수를 증가시키기 위한 보다 개선되고, 진보된 탭인덕터와 스너버 캐패시터/다이오드로 구성된 2차 측 보조회로 적용 영전압 $\cdot$영전류 스위칭 3 레벨(Level) DC/DC컨버터에 대한 주 회로특성분석 및 7kW, 30kHz DC/DC 컨버터의 시제품을 제작하여 실험한 결과에 대해 서술하고자 한다.

• Journal of Power Electronics
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• 제16권2호
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• pp.512-521
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• 2016

Cascaded H-bridge multilevel (CHBML) inverters usually include a large number of isolated dc-voltage sources. Some faults in the dc-voltage sources result in unequal cell dc voltages. Unfortunately, the conventional phase-shifted carrier (PSC) PWM method that is widely used for CHBML inverters cannot eliminate low frequency sideband harmonics when the cell dc voltages are not equal. This paper analyzes the principle of sideband harmonic elimination, and proposes an improved PSCPWM that can eliminate low frequency sideband harmonics under the condition of unequal dc voltages. In order to calculate the carrier phases, it is necessary to solve transcendental equations for low frequency sideband harmonic elimination. Therefore, an approach based on the artificial bee colony (ABC) algorithm is presented in this paper. The proposed PSCPWM method enhances the reliability of CHBML inverters. The proposed PSCPWM is not limited to CHBML inverters. It can also be applied to other types of multilevel inverters. Simulation and experimental result obtained from a prototype CHBML inverter verify the theoretical analysis and the achievements made in this paper.

• Journal of Power Electronics
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• 제16권2호
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• pp.425-435
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• 2016

This paper presents a comprehensive theoretical analysis and an accurate calculation method of the dead-time required to achieve zero-voltage-switching (ZVS) in a battery charger with the phase-shifted full-bridge (PSFB) topology. Compared to previous studies, this is the first time that the effects of nonlinear output filter inductance, varied Miller Plateau length, and blocking capacitors have been considered. It has been found that the output filter inductance and the Miller Plateau have a significant influence on the dead-time for ZVS when the load current varies a lot in battery charger applications. In addition, the blocking capacitor, which is widely used to prevent saturation, reduces the circulating current and consequently affects the setting of the dead-time. In consideration of these effects, accurate analytical equations of the dead-time range for ZVS are deduced. Experimental results from a 1.5kW PSFB battery charger prototype shows that, with the proposed analysis, an optimal dead-time can be selected to meet the specific requirements of a system while achieving ZVS over wide load range.

• Journal of Power Electronics
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• 제6권1호
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• pp.45-51
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• 2006

A new high efficiency phase shifted full bridge (PSFB) converter for the power sustaining module of a plasma display panel (PDP) is proposed in this paper. The proposed converter employs a voltage doubler rectifier without an output inductor. Since it has no output inductor, the voltage stresses of the secondary rectifier diodes can be clamped at the output voltage level. No dissipative resistor-capacitor (RC) snubber for rectifier diodes is needed. Therefore, high efficiency, as well as, a low noise output voltage can be realized. Due to the elimination of the large output inductor, it features a simple structure, lower cost, smaller mass and lighter weight. Furthermore, the proposed converter has wide zero voltage switching (ZVS) ranges with low current stresses of the primary switches. Also the resonance between the leakage inductor of the transformer and the capacitor of the voltage doubler cell reduces the current stresses of the rectifier diodes. In this paper, operational principles, an analysis of the proposed converter and experimental results are presented.

• 한국항행학회논문지
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• 제7권1호
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• pp.14-21
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• 2003

장거리 $3{\times}40$ Gbps 강도 변조 직접 검파 방식의 파장 분할 다중 시스템에서 색 분산과 자기 위상 변조에 의한 광 펄스 왜곡을 최상으로 보상할 수 있는 최적의 펌프 전력을 컴퓨터 시뮬레이션을 통해 살펴보았다. 본 논문에서 고찰한 파장 분할 다중 시스템은 전체 전송로 중간에 HNL-DSF (highly nonlinear dispersion shifted fiber)의 광 위상 공액기를 두어 광 신호 왜곡을 보상하는 경로 평균 강도 근사 (PAIA : Path-Averaged Intensity Approximation) 기법의 MSSI (Mid-Span Spectral Inversion)가 적용된 시스템이다. 우선 HNL-DSF는 광대역 파장 분할 다중 전송에서 매우 유용한 비선형 매질이라는 것을 확인할 수 있었고, 두 번째 광 전송로로 입사되는 공액파의 전력을 입력 광 신호의 전력과 같아지게 하는 HNL-DSF 광 위상 공액기의 펌프 전력에서 최상의 보상이 얻어지는 것을 확인할 수 있었다. 결과적으로 PAIA MSSI 기법에 전송 거리에 관계한 최적 펌프 전력을 갖는 HNL-DSF 광 위상 공액기를 적용하면 장거리 대용량 파장 분할 다중 시스템의 구현이 가능하다는 것을 확인할 수 있었다.

• Journal of Power Electronics
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• 제18권4호
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• pp.1154-1164
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• 2018

In single-phase magnetically coupled resonant (MCR) wireless power transfer (WPT) systems, the transfer characteristics, including the output power and transfer efficiency, are significantly influenced by the spatial scales of its coils. As a potential alternative, a three-phase MCR WPT system with cylinder-shaped coils that are excited in a voltage-fed manner has been proposed to satisfy the requirements of compact space. This system adopts a phase-shifted angle control scheme to generate a rotating magnetic field and to realize omnidirectional WPT that is immune to spatial scales. The magnetic field model and equivalent circuit models are built to holistically analyze the system characteristics under different angular misalignments. Research results show that the transfer characteristics can be improved by modulating the phase-shifted angle in each phase. Experiments have also been carried out to evaluate the accuracy of the theoretical analysis and to confirm the validity of the system modeling method.

• 한국광학회지
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• 제13권3호
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• pp.182-188
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• 2002

위상이동 간섭무늬 투영 방법을 이용한 3차원 형상측정 시스템의 위상계산오차를 분석하였다. 본 연구에서 다룬 오차의 요소에는 물체 표면의 특성에 따라 검출기에 나타나는 양자화 크기의 변이 효과, 물체 표면에 맺히는 간섭무늬 패턴의 초점 어긋남 효과, 간섭무늬의 위상이동 오차에 의한 효과, 위상 이동된 간섭무늬 패턴이 투영된 여러 개의 물체 상을 받아들이는 도중에 시스템 및 주위 환경 변화에 의한 오차, 그리고 투영되는 격자 패턴의 왜곡에 의한 효과들을 계산하고 논의하였다.

• 전기의세계
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• 제27권6호
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• pp.63-68
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• 1978

To convert into multiphase from single phase are often necessary for industry field. In oder to convert of phase, phase shifted voltages are first buileded by single phase and then must combine with these voltages adequately. This paper aims at the description of the way of phase shift by means of turning on or turning off through natural commutation and forced commutation methods with firing angle of thyristor pating a role of switching controlled adequately. Experimental result of the Phase Shift with the Thyristors Utilized has been turned out to shift the phase to 60.deg., 90.deg., 120.deg., and other angles.