• 전기의세계
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• 제31권3호
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• pp.226-234
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• 1982

DC choppers are usually used to control the DC motor by varying the average value of DC input voltage to the DC motors. In this paper, a chopper circuit is suggested and reconstructed by replacing the free-wheeling diode with the parallel capacitor in the conventional ones. It is demonstrated that this chopper circuit with capacitor can reduce the ripples of the output voltage and current in contrast to those of the chopper with diode, and it can be controlled the output waveforms smoothly at high power demand.

• 마이크로전자및패키징학회지
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• 제15권1호
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• pp.59-64
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• 2008

최근 DC-DC 초퍼의 소형경량화 및 저소음화를 위해서 초퍼에 사용한 전력용 반도체 스위치의 스위칭 주파수를 증대시키고 있다. 이에 따른 스위칭 손실의 증대는 초퍼의 효율을 상당히 감소시키는 요인으로 주어진다. 이를 해결하기 위해 본 논문에서는 초퍼에 사용한 반도체 스위치의 턴-온, 턴-오프를 소프트 스위칭(영전류 또는 영전압 스위칭)으로 동작시켜 스위칭 손실을 최소화하는 새로운 고효율의 DC-DC 초퍼를 제안한다. 제안한 초퍼의 소프트 스위칭 동작은 스위치의 동작 시점에 부분공진 회로가 형성되어 인덕터의 전류와 커패시터의 전압이 영으로 될 때 스위치를 동작시키는 부분공진 기법이 적용된다. 또한 제안한 초퍼에 적용된 부분공진 회로는 승압용으로 사용한 인덕터와 스너버 커패시터에 의해 설계되어 초퍼의 회로 토폴로지가 간단하다. 컴퓨터 시뮬레이션과 실험결과를 통해 제안한 DC-DC 초퍼의 타당성이 입증된다.

• Journal of Power Electronics
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• 제4권3호
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• pp.161-168
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• 2004

This paper presents a new circuit topology of high-frequency soft switching commutation boost type PWM chopper-fed DC-DC power converter with a loadside auxiliary passive resonant snubber. In the proposed boost type chopper-fed DC-DC power converter circuit operating under a principle of ZCS turn-on and ZVS turn-off commutation, the capacitor and inductor in the auxiliary passive resonant circuit works as the lossless resonant snubber. In addition to this, the voltage and current peak stresses of the power semiconductor devices as well as their di/dt or dv/dt dynamic stress can be effectively reduced by the single passive resonant snubber treated here. Moreover, it is proved that chopper-fed DC-DC power converter circuit topology with an auxiliary passive resonant snubber could solve some problems on the conventional boost type hard switching PWM chopper-fed DC-DC power converter. The simulation results of this converter are illustrated and discussed as compared with the experimental ones. The feasible effectiveness of this soft witching DC-DC power converter with a single passive resonant snubber is verified by the 5kW, 20kHz experimental breadboard set up to be built and tested for new energy utilization such as solar photovoltaic generators and fuel sell generators.

• Journal of Power Electronics
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• 제5권2호
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• pp.99-103
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• 2005

In this paper, a novel circuit topology of a three-winding coupling inductor-assisting a high-frequency PWM boost chopper type DC-DC power converter with a high boost voltage conversion ratio and low switch voltage stress is proposed for the new energy interfaced DC power conditioner in solar photovoltaic and fuel cell generation systems. The operating principle in a steady state is described by using its equivalent circuits under the practical condition of energy processing of a lossless capacitive snubber. The newly-proposed power MOSFET boost chopper type DC-DC power converter with the three-winding coupled inductor type transformer and a single lossless capacitor snubber is built and tested for an output power of 500W. Utilizing the lower voltage and internal resistance power MOSFET switch in the proposed PWM boost chopper type DC-DC power converter can reduce the conduction losses of the active power switch compared to the conventional model. Therefore, the total actual power conversion efficiency under a condition of the nominal rated output power is estimated to be 81.1 ％, which is 3.7％ higher than the conventional PWM boost chopper DC power conversion circuit topology.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.115-117
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• 2007

This paper is analyzed for DC-DC chopper performance of high efficiency added in electric isolation. The general converters of high efficiency are made that the power loss of the used switching devices is minimized. To achieve high efficiency system, the proposed chopper is constructed by using a partial resonant circuit. The control switches using in the chopper are operated with soft switching for a partial resonant method. The control switches are operated without increasing their voltage and current stresses by the soft switching technology. The result is that the switching loss is very low and the efficiency of chopper is high. And the proposed chopper is added in a electric isolation. When the power conversion system is required to electric isolation, the proposed chopper is adopted with system development of high efficiency. The soft switching operation and the system efficiency of the proposed chopper is verified by digital simulation and experimental results.

• 대한전기학회논문지
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• 제36권3호
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• pp.171-178
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• 1987

A study of two phase chopper system with four separate groups of DC motors in powering. A novel two phase chopper system with four separate groups of DC motors which applies the principles of two phase chopper with two separate groups of DC motors is dealt with this article. The main circuit consists of eight sets of chopping parts, four diodes and four separate groups of DC motors. Four groups of DC motors are driven through the series and parallel connections to each other in accordance with the operating conditions of the choppers. Although the proposed chopper circuit requires more circuit elements than the conventional two phase chopper system with combined output or two phase chopper system with two separate groups of DC motors, it has the following advantages` (1). It is possible to drive twice as much motors as conventional system does, using esisting receiving-and equipments and motors. (2). It is possible to control load voltage continuously from 0 to source voltage by changing time-ratio from 0 to 1. (3). Load current division becomes equalized. Therefore it is possible to drive not only series motors but also shunt and separately exited motors. (4). When smoothing reactor L is small, harmonic components of the proposed circuit is not so large. Therefore, the value of L can be determined from viewpoints of allowable value of ripple-ratio and current unbalance factor.

• 전기학회논문지
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• 제66권5호
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• pp.750-756
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• 2017

This paper presents a method for DC voltage control of HVDC system connection of offshore wind farms. In the event of fault in AC grid, HVDC system need to meet LVRT regulations. When HVDC system meet LVRT regulation, unbalance is caused between power input and power output for DC link. Therefore, LVRT regulation lead to DC voltage increase of HVDC system. To control the DC voltage increase, the chopper resistor can be suggested. In this paper, DC voltage suppression is proposed using chopper resistor and de-loading. The effectiveness of the chopper resistor was verified using PSCAD/EMTDC.

• 전기전자학회논문지
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• 제13권4호
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• pp.82-88
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• 2009

본 논문에서는 새로운 고효율의 절연형 스텝 업-다운 DC/DC 초퍼에 대해 해석하였다. 일반적으로 고효율의 초퍼를 만들기 위해서는 전력변환기내에 사용된 반도체 스위칭 소자의 손실이 최소화 되어야 한다. 본 논문에서는 부분공진 회로를 초퍼에 추가하여 고효율을 실현시킨다. 제안한 초퍼에 사용된 제어용 스위칭 소자들은 부분공진기법에 의해 소프트 스위칭으로 동작하고, 이에 따른 제어용 스위칭 소자들은 전압과 전류의 스트레스 없이 동작한다. 그 결과 제안한 초퍼는 스위칭 손실의 저감에 의해 고효율로 구동한다. 그리고 제안한 초퍼는 펄스 변압기를 이용하여 입력단과 출력단을 절연시켜, 전기적 절연이 요구되는 전력변환기들에 적용되어 고효율의 전력변환시스템을 개발할 수 있는 장점이 부여된다. 제안한 절연형 스텝 업-다운 초퍼의 소프트 스위칭 동작과 시스템 효율은 다양한 시뮬레이션과 실험결과를 통해 그 타당성이 입증된다.

• 전기의세계
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• 제28권1호
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• pp.67-72
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• 1979

The most difficult problem encountered in the DC Chopper is the improvement in it's output waveforms and the commutation failure. Thus, this paper deals with the Load Insensitive DC Chopper that produces a quasi-pure square wave over the entire load range, and doesn't fail the commutation. The authors compared voltage and current waveforms from the laboratory model with those from the computer simulation, and it's characteristics is discussed.

• 제어로봇시스템학회논문지
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• 제3권6호
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• pp.576-581
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• 1997

DC-DC converter with chopper is seen to have problems, such as, loop instability and degradation of transient response, due to the interaction between input filter and switching regulator. In this paper, the switching regulator consisting of input filter and double chopper is analyzed, and the state space model at continuous current mode and the transfer function between duty ratio of switching pulse and output voltage are derived. The controller in this paper is designed as feedforward(P) and feedback(PI) control scheme to minimize the variation of output voltage, and computer simulation results are presented to show the performance of the proposed controller.