• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.10
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• pp.27-33
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• 2016

This paper proposes a Low Noise Amplifier (LNA) with chopper stabilization technique with a sample-hold circuit. Chopper stabilization technique is effective in terms of reducing low frequency offset and flicker noise. Conventional chopper amplifier has a disadvantage in area because of using Low Pass Filter (LPF) for remove chopping spike. The proposed chopper amplifier employed sample and hold technique to decrease chopping spike instead of LPF that improves 36% in voltage damping and 11% in area.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.323-329
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• 1998

In this paper, we compose of the utility interactive photovoltaic(PV) generation system with a PWM stepdown chopper and a current source inverter. The stepdown chopper is controlled by the several gate pulses (twice frequency of utility voltage, square pulse and without the chopper) of chopper part to reduce pulsation of DC current and size of DC reactor. PV current only is measured for maximum power point tracking without any influence on the variation of insolation and temperature. Therefore, we can control modulation factor of the chopper to operate at maximum power point of solar cell. And, the utility interactive photovoltaic generation system supplies an AC power to the load and the utility power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.9
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• pp.1584-1588
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• 2007

This paper proposed the voltage compulsion method that used chopper for light dimming control of fluorescent lamp. During the dimming period, electronic ballasts have the bad characteristics such as low power factor, high THD(Total Harmonic Distortion) and etc. The proposed dimmer improves power factor, THD of electronic ballast and has benefit such as low cost, simple build up.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.370-373
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• 1997

In this paper, we compose of the stepdown chopper and the current source inverter. Because dc side current of the current source inverter pulse with twice frequency of utility, we control that modulation factor of chopper is pulsed twice frequency. Therefore if voltage across the dc reactor equal to zero, it tis decreased. And we control modulation factor of the chopper to operate at maximum power point around of solar cell.

• Journal of Biomedical Engineering Research
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• v.2 no.1
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• pp.55-64
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• 1981

The important parameters of DC amplifier, which is widely use4 for the medical and engineering fields, are input offset voltage and temperature drift. Chopping amplifier reduces approximately 10% the parameters changing than monolithic operational amplifier. In this study, a chopping amplifier with semiconductor chopper is designed and tested, this chopper is realized by CMOS analog switch and timing circuits. The test results approve that designed amplifier is suitable for precision instrument DC amplifier.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.4
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• pp.349-356
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• 1990

In order to control DC motors for electric cars by chopper system, four quadrant operations - forward powering, forward regenerative braking, reverse powering, reverse regenerative braking - are needed. For the four quadrant operations, the separately - excited DC motors are used in this study. The conversion of each quadrant operation has been obtained by 1) adopting the two phase chopper system with combined output for the armature control, and 2) the single phase chopper system for the field control.

• 전기의세계
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• v.25 no.4
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• pp.28-31
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• 1976

Thyristor는 많은 전력기기와 결합되어 전기기기 전반의 양상을 크게 변화시키고 있다. 예를 들면 변압기의 불꽃없는 탭이나 회전기의 정류자에 대치되는 무정류자전동기와 그리고 개폐기, 차단기의 대용등을 생각할 수 있다. 전력변환장치로서는 (1)직류전력을 조정하는 목적으로 Thyristor를 일종의 스위치로써 직류전압을 단속시켜 직류평균전력을 제어하는 DC Chopper (2)교류전원에 두개의 Thyristor를 역병렬접속하여 교류전류의 통전기간을 위상제어에 의하여 교류를 제어하는 AC Chopper (3)직류를 교류로 변환하는 자여식 inverter등이 있다. 본 해설에서는 지면관계상 D.C Chopper방식에 대한 기본회로와 그의 이용만을 취급한다.

• 전기의세계
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• v.28 no.1
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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.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.3
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• pp.19-25
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• 2008

In this paper, author proposes a novel step-up AC-DC chopper operated with power factor correction(PFC) and with high efficiency. The proposed chopper behaves with discontinuous current control(DCC) of input current. The input current waveform in the proposed chopper is got to be a discontinuous sinusoid form in proportion to magnitude of ac input voltage under the constant duty cycle switching. Therefore, the input power factor is nearly unity and the control method is simple. In the general DCC chopper, the switching devices are turned-on with the zero current switching, but turn-off of the switching devices is switched at current maximum value. To achieve a soft switching of the switching rum-off, the proposed chopper is used a new partial resonant circuit. The result is that the switching loss is very low and the efficiency of chopper is high.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.1
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• pp.59-64
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• 2008

Recently, DC-DC choppers must be increased switching frequency in order to achieve a small size, a light weight and a low noise. However, the switches of chopper are subjected to high switching power losses and switching stresses. As a result of these, the chopper system bring on a low power efficiency. To improved these, this paper is studied on a new DC-DC chopper of high efficiency operated with soft switching(that is, zero current switching and zero voltage switching, ZVCS), of semiconductor switches using in chopper. The soft switching operation is applied to a partial resonant method that the switches operate at zero current of inductor and zero voltage of capacitor in resonant circuit. And the partial resonant circuit makes use of a inductor using step-up and a snubber capacitor, the circuit topology of chopper is simple. Some simulative results on computer and experimental results confirm the validity of analytical results of the DC-DC chopper.