• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.83-85
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• 2019

The use of high voltage gain converters is essential for the distributed power generation systems with renewable energy sources such as the fuel cells and solar cells due to their low voltage characteristics. In this paper, a high voltage gain topology combining cascode Inverting Buck-Boost converter and voltage multiplier structure is introduced. In proposed converter, the input voltage is connected in series at the output, the portion of input power is directly delivered to the load which results in continuous input current. In addition, the voltage multiplier stage stacked in proper manner is not only enhance high step-up voltage gain ratio but also significantly reduce the voltage stress across all semiconductor devices and capacitors. As a result, the high current-low voltage switches can be employed for higher efficiency and lower cost. In order to show the feasibility of the proposed topology, the operation principle is presented and the steady-state characteristic is analyzed in detail. A 380W-40/380V prototype converter was built to validate the effectiveness of proposed converter.

• 전력전자학회논문지
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• 제23권5호
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• pp.299-304
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• 2018

An ideal circuit breaker should supply electric power to loads without losses in a conduction state and completely isolate the load from the power source by providing insulation strength in a break state. Fault current is relatively easy to break in an Alternating Current (AC) circuit breaker because the AC current becomes zero at every half cycle. However, fault current in DC circuit breaker (DCCB) should be reduced by generating a high arc voltage at the breaker contact point. Large fire may occur if the DCCB does not take sufficient arc voltage and allows the continuous flow of the arc fault current with high temperature. A semiconductor circuit breaker with a power electronic device has many advantages. These advantages include quick breaking time, lack of arc generation, and lower noise than mechanical circuit breakers. However, a large load capacity cannot be applied because of large conduction loss. An extinguishing technology of DCCB with polymeric positive temperature coefficient (PPTC) device is proposed and evaluated through experiments in this study to take advantage of low conduction loss of mechanical circuit breaker and arcless breaking characteristic of semiconductor devices.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.337-340
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• 2007

In the dissertation, a power conversion system for fuel cell is composed of a PWM inverter with LC filter in order to convert fuel cell voltage to a single phase 220[V], In addition, new insulated DC-DC converters are proposed in order that fuel cell voltage is boosted to 380[V]. In this paper, it requires smaller components than existing converters, which makes easy control. The proposed DC-DC converter controls output power by the adjustment of phase-shift width using switch S5 and S6 in the secondary switch, which provides 93-97[%] efficiency in the wide range of output voltage. Fuel cell simulator is implemented to show similar output characteristics to actual fuel cell. Appropriate dead time td enables soft switching to the range where the peak value of excitation current in a high frequency transformer is in accordance with current in the primary circuit. Moreover, appropriate setting to serial inductance La reduces communication loss arisen at light-load generator and serge voltage arisen at a secondary switch and serial diode. Finally, TMS320C31 board and EPLD using PWM switching technique to act a single phase full-bridge inverter which is planed to make alternating current suitable for household.

• 조명전기설비학회논문지
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• 제18권1호
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• pp.105-114
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• 2004

본 논문에서 반도체 소자에 대한 DC 파라미터 검사를 위한 회로를 설계하였다. DC 파라미터 검사기는 반도체 소자의 DC 특성을 검사하는 시스템 이다. 본 논문에서 설계한 회로에서는 파라미터를 검사하기 위해 전압(전류)인가 전류(전압)측정 방법을 사용하도록 회로를 설계하였다. 설계한 회로를 OR-CAD를 사용하여 실험하였으며, 설계된 회로의 실험결과를 통해 좋은 성능을 가짐을 알 수 있었다.

• 전기학회논문지
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• 제57권10호
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• pp.1796-1801
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• 2008

In this paper, a new current based maximum power point tracking (CMPPT) method is proposed for a single phase photovoltaic power conditioning system and the current based MPPT modifies incremental conductance method. The current based MPPT method makes the entire control structure of the power conditioning system simple and uses an inherent current source characteristic of solar cell array. In addition, digital phase locked loop using an all pass filter is introduced to detect phase of grid voltage as well as peak voltage. Controllers about dc/dc boost converter, dc-link voltage, dc/ac inverter is designed for a coordinated operation. Furthermore, PI current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. 3kW prototype photovoltaic power conditioning system is built and its experimental results are given to verify the effectiveness of the proposed control schemes.

• 전기전자학회논문지
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• 제25권4호
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• pp.741-749
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• 2021

본 논문에서 제안한 전류형 LLC AC to DC 고주파 공진 컨버터는 스위치 양단에 병렬로 공진 커패시터(C₁, C₂)를 연결함으로써 ZVS(Zero Voltage Switching)동작 뿐만 아니라 2차측 Diode의 ZCS(Zero Current Switching) 동작이 가능하므로 스위칭 소자의 턴-온 및 2차측 다이오드의 턴-오프 손실을 저감시킬 수 있다. 본 논문에서 제안한 LLC AC to DC 고주파 공진 컨버터의 회로 해석은 무차원화 제어 파라메타를 도입하여 범용성 있게 기술하였다. 또한 제안한 LLC AC to DC 고주파 공진 컨버터의 운전 특성은 무파원화 제어 주파수(μ), 무차원화 저항(λ) 등의 무차원화 제어 파라메타를 이용하여 특성 평가를 수행하였다. 특성 평가를 통한 특성값을 기초한 LLC AC to DC 고주파 공진 컨버터 설계 기법의 일예를 제시하였으며, 실험 및 PSIM 시뮬레이션을 통해 이론 해석의 정당성을 입증하였다.

• Journal of Power Electronics
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• 제2권3호
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• pp.199-205
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• 2002

This paper compares three kinds of soft-switching circuits from viewpoints of surge suppression, load characteristic, and power efficiency for a tapped-inductor buck converter with low voltage and high current. As a result, these soft-switching techniques have achieved much higher efficiency of 80 % when compared with a hard-switching buck converter for the output condition of 1V and 20A.

• 전기학회논문지
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• 제62권3호
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• pp.355-364
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• 2013

Respect to the input AC voltage and output DC voltage, conventional three-phase PWM rectifier is classified as the voltage type rectifier with boost capability and the current type rectifier voltage with buck capability. Conventional PWM rectifier can not at the same time the boost and buck capability and its bridge is weak in the shoot- through state. These problems can be solved by Z-source PWM rectifier which has all characteristic of voltage and current type PWM rectifier. By shoot-through duty ratio control, the Z-source PWM rectifier can buck and boost at the same time, also, there is no need to consider the dead time. This paper proposes the input AC voltage sensorless control method of a three-phase Z-source PWM rectifier in order to accomplish the unity input power factor and output DC voltage control. The proposed method is estimated the input AC voltage by using input AC current and output DC voltage, hence, the sensor for the input AC voltage detection is no needed. comparison of the estimated and detected input AC voltage, estimated phase angle of the input voltage, the output DC voltage response for reference value, unity power factor, FFT(Fast Fourier Transform) of the estimated voltage and efficiency are verified by PSIM simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1324-1326
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• 2000

This paper proposes a Current-Fed Push Pull type DC-DC converter using LCCC Resonant circuit and Zero Voltage Switching function to reduce turn on and off loss at the switching instants. This paper have the advantage which is able to operating safely in load short, because of DC reactor is connected with resonance reactor in order to supply a fixed current with low ripple from DC Power supply. The capacitor ($C_1$, $C_2$) connected in switch are common using as resonance capacitor and ZVS capacitor. The analysis of the proposed Current-Fed Push Pull type DC-DC converter is generally described by using normalized parameter, and we have evaluated characteristic values which is needed to design a circuit. We confirm a rightfulness theoretical analysis by comparing a theoretical values and experimental values obtained from experiment using MOSFET as switching devices.

• 반도체디스플레이기술학회지
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• 제21권3호
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• pp.80-86
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• 2022

In this paper, the optimal design and circuit simulation verification results of an LLC resonant half-bridge dc-dc converter using a steady-state model with internal loss resistance are reported. Above all, the input/output voltage gain and frequency characteristic equations in the steady-state were derived by reflecting the internal loss resistance in the equivalent circuit. Based on the results, an LLC resonant half-bridge dc-dc converter with an input voltage of 360-420V, an output voltage of 54V, and a maximum power of 3kW was designed, and to verify the design, the PSIM circuit simulation was executed to compare and analyze the result. In particular, the operating range of the converter could be drawn from the frequency characteristic graph of the voltage gain, and when the converter was operated under light and maximum load conditions, it was confirmed that similar results were obtained by comparing simulation results and calculation results in the switching frequency characteristic graph. In addition, the change of the switching frequency with respect to the load current at each input voltage was compared with the calculated value and the simulation result. As a result, it was possible to confirm the usefulness of the analysis result reflecting the internal loss resistance proposed in this paper and the process of the optimal design.