• 전력전자학회:학술대회논문집
• /
• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
• /
• pp.71-75
• /
• 1996

As the Three-level ZVS PWM DC-DC converter operates likewise full-bridge ZVS PWM DC-DC converter and the blocking voltage of each switching device is a half of the DC-link voltage, it is suitable for the high imput voltage applications. However, it has some problems as follows; The blocking voltage of each devices is unbalanced and it causes the power losses of the inner switching devices to be increased. Also, it has narrow load range so that the switching losses and the efficiency are reduced as it goes to the light load. This paper presents an nove Three-level ZVS PWM DC-DC converter, which can reduce the overvoltage of the outer switches, eliminate the unbalance of the voltage sharing between the switches at turn-off due to the stray inductances, and operate from no load to full load. The characteristics and the performances of the proposed Three-level ZVS PWM DC-DC converter are verified by simulation and experimental results

• Journal of Power Electronics
• /
• 제11권4호
• /
• pp.561-567
• /
• 2011

This paper presents a high-efficiency power conditioning system (PCS) for grid-connected photovoltaic (PV) modules. The proposed PCS consists of a step-up DC-DC converter and a single-phase DC-AC inverter for the grid-connected PV modules. A soft-switching step-up DC-DC converter is proposed to generate a high DC-link voltage from the low PV module voltage with a high-efficiency. A DC-link voltage controller is presented for constant DC-link voltage regulation. A half-bridge inverter is used for the single-phase DC-AC inverter for grid connection. A grid current controller is suggested to supply PV electrical power to the power grid with a unity power factor. Experimental results are obtained from a 180 W grid-connected PV module system using the proposed PCS. The proposed PCS achieves a high power efficiency of 93.0 % with an unity power factor for a 60 Hz / 120 Vrms AC power grid.

• 전기학회논문지
• /
• 제65권9호
• /
• pp.1479-1485
• /
• 2016

This paper presents DC voltage recovery time improvement method in DC link of High Voltage Direct Current (HVDC) with offshore wind farm. The wind farm should be satisfied Low Voltage Ride Through(LVRT) control strategy when grid faults occur. The LVRT control strategy indicates actions which have to be executed according to the voltage dip ratio and the fault duration. However, The LVRT control strategy makes between wind farm and power system through DC Link voltage when grid fault occurs. The de-loading scheme is one of the method to control the DC voltage. But de-loading scheme need to long DC voltage recovery time. Thus, this paper proposes an improved de-loading scheme and we analysis DC voltage and active power reference through a simulation.

• 전기학회논문지
• /
• 제63권11호
• /
• pp.1622-1625
• /
• 2014

The main measurement uncertainty factors in DC high-voltage dividers for a national high-voltage standard are the measurement uncertainty of low-voltage arm and the stability of a high-voltage supply. In this study, the uncertainties by the two factors are greatly improved. As a result the measurement uncertainty for the DC high-voltage divider is reduced from $16{\times}10^{-6}(k=2)$ to $8{\times}10^{-6}(k=2)$ which is at international level.

• 한국산업융합학회 논문집
• /
• 제22권3호
• /
• pp.365-371
• /
• 2019

Recently, the demonstration and research on the power transmission using high voltage DC such as HVDC(High Voltage DC), Smart Grid, DC transmission and distribution have been actively conducted. In order to control the power converter in high-voltage DC power transmission system, SMPS(Switching Modulation Power Supply) for power converter control using high-voltage DC input is essential. However, the demand for high-pressure SMPS is still low, so the development is not enough. In the low-output SMPS using the high-voltage input, it is difficult to achieve high efficiency due to the switching transient loss especially at light load. In this paper, we propose a new switching scheme for high power SMPS control for low output power. The proposed method can provide better efficiency increase effect in the light load region compared to the existing PWM method. To verify the feasibility of the proposed method, a 40 W SMPS for HVDC MMC(Modulation Multi-level Converter) was designed and verified by simulation.

• 전기학회논문지P
• /
• 제66권2호
• /
• pp.63-68
• /
• 2017

This paper proposes a new non-isolated DC conversion circuit topology of the voltage source coupled inductor series resonant high-frequency PFM controlled boost chopper type DC-DC power converter using two in one IGBT power module, which can efficiently operate under a principle of zero current soft switching for wide output regulation voltage setting ranges and wide fluctuation of the input DC side voltage as well as the load variation ranges. Its steady state operating principle and the output voltage regulation characteristics in the open-loop-based output voltage control scheme without PI controller loop are described and evaluated from theoretical and experimented viewpoints. Finally, in this paper the computer-aided simulation steady-state analysis and the experimental results are presented in order to prove the effectiveness and the validity of voltage regulation characteristics of the proposed series resonant zero current soft switching boost chopper type DC-DC power converter circuit using IGBTs which is based on simple pulse frequency modulation strategy more than, 20kHz.

• 전력전자학회논문지
• /
• 제14권3호
• /
• pp.220-227
• /
• 2009

본 논문은 고전압 DC 파워 서플라이 적용을 위한 높은 전환 비의 자려발진 DC/DC 전력 변환 회로에 관한 것으로써, 하나의 스위치, 하나의 인덕터, 그리고 다수개의 캐패시터와 다이오드로 구성된다. 기존의 극성 반전 형DC/DC 컨버터 회로와 비교하여, 고압 변환 트랜스포머 대신에 인덕터를 사용할 수 있어, 자기 소자의 부피 및 크기는 물론 원가저감이 가능하다. 또한 자려 발진(Self Oscillation) 방식을 사용하여 별도의 제어 IC가 필요 없으므로, 회로구성이 대단히 간단하고, 저가격의 전원 회로를 만들 수 있다. 또한 다이오드들의 전압 스트레스가 감소하여 저가격 고성능의 고압 변환장치 구현이 가능하다. 제안된 회로의 동작원리를 설명하고, 타당성을 Simulation 및 실험을 통하여 검증한다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권4호
• /
• pp.183-190
• /
• 2003

We report the performance of an open-frame type low-voltage high-current DC-DC converter module developed using an active clamp forward converter circuit and current doubler rectifier. The converter module is designed with the specifications of an 1.8V output voltage, 25A output current, and 36-75V input voltage. The synchronous rectifier is used to reduce the conduction fuss at high current level and current-mode control is adapted to enhance the flexibility in the system configuration. A prototype converter module is successfully implemented within 10mm height and half brick size (58${\times}$61mm), and recorded an 84% efficiency and 4% voltage regulation for the entire input voltage range, thereby demonstrating its application potentials to future telecommunication electronics.

• 대한전기학회논문지:전력기술부문A
• /
• 제52권4호
• /
• pp.183-183
• /
• 2003

We report the performance of an open-frame type low-voltage high-current DC-DC converter module developed using an active clamp forward converter circuit and current doubler rectifier. The converter module is designed with the specifications of an 1.8V output voltage, 25A output current, and 36-75V input voltage. The synchronous rectifier is used to reduce the conduction fuss at high current level and current-mode control is adapted to enhance the flexibility in the system configuration. A prototype converter module is successfully implemented within 10mm height and half brick size (58×61mm), and recorded an 84% efficiency and 4% voltage regulation for the entire input voltage range, thereby demonstrating its application potentials to future telecommunication electronics.

• Journal of Power Electronics
• /
• 제19권3호
• /
• pp.676-690
• /
• 2019

This paper presents a switched capacitor (SC) based bidirectional dc-dc converter topology for high voltage gain applications. The proposed converter is able to operate with multiple integral voltage conversion ratios based on user input. The architecture of a user-friendly, inductor-less multi-voltage-gain bidirectional dc-dc converter is proposed in this study. The inductor-less or magnetic-less design of the proposed converter makes it effective in higher temperature applications. Furthermore, the proposed converter has a reduced component count and lower voltage stress across its switches and capacitors when compared to existing SC converters. An output impedance analysis of the proposed converter is presented and compared with popular existing SC converters. The proposed converter is simulated in the OrCAD PSpice environment and the obtained results are presented. A 200 W hardware prototype of the proposed SC converter has been developed. Experimental results are presented to validate the efficacy of the proposed converter.