• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권5호
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• pp.230-237
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• 2003

Current mode control has been used for DC to DC converters for over twenty years. There are many different control schemes which use the inductor current signal in one way or another to control the DC to DC converter. In this paper, the state space averaging technique is applied for the analysis of flyback type current mode control circuit. We made real converter for the guarantee of stable output characteristic and proper design of feedback circuit. The validity of proposed method is verified from test result. The improvement of stability is confirmed by sinusoidal signal injection method with isolated transformer. It is known that phase margin is sufficient and gain crossover frequency fc is early 1/5 of switching frequency, fs, from the experimental result with frequency response analyzer.

• 대한전기학회논문지
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• 제40권1호
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• pp.58-66
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• 1991

In inverters, time delays are inserted in the switching signals to prevent the dc lind shortage. This causes detrimental effects on the performance of the inverters, that is, the fundamental voltage drop and the generation of low order harmonics. This paper derives simple formula to describe the time delay effects in PWM inverters, where the effects may become significant because of relatively high switching frequencies. To compensate the tice delay effects, this paper presents two methods which are suitable for sinusoidal PWM and memory-based PWM respectively. Both are simple, easy to implement, and are shown to be effective, through the experiments, in improving the output waveform of PWM inverters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2259-2261
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• 1997

In this paper, control scheme of the three phase VSI(Voltage Source Inverter) for 200KVA UPS is described. The proposed controller is designed to robust against parameter variations, disturbances and load change using PI controller. The switching pattern is determined to Ramp Comparison Method. The inverter provides pure sinusoidal output voltage with very low THD (Total Harmonic Distortion). Finally, the performance of the proposed inverter is shown by experimental result.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.543-545
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• 1996

In this paper, a voltage and current control scheme of a three-phase voltage source inverter for UPS is described. The inverter provides pure sinusoidal output voltage with very low THD(Total Harmonic Distortion). The proposed controller is designed to robust against the load change, parameter variations, and disturbances using PI controller. The switching pattern is determined to Space Vector Modulation. Finally, the performance of the proposed inverter is shown and discussed by simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.501-503
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• 1996

In this paper, a novel control strategy for PWM current source converter and inverter is proposed, applying a multivariable state feedback control. The PWM converter controls line current to be sinusoidal and make input power factor unity. In addition, the modulation index control of dc link current is carried out, which produces lower loss of switching devices. Since the voltage control of inverter output filter capacitor is performed a decoupling of the d-q current of the induction motor is well retained. With the proposed algorithm, both high dynamic responses and satisfactory static performance can obtained.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.318-320
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• 1996

This paper describes a new dc/ac inverter system, which makes use of parallel loaded high frequency resonant inverter consisting of full bridge, for achieving sinusoidal ac waveform. Because current throughout switch at turn-on is always zero in proposed inverter, low stress and low switching loss is achieved. Operating characteristic of proposed system is analyzed in per unit system using computer simulation. Output voltage of it include low harmonics and almost close tn sine wave.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.291-293
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• 2003

A semiconductor switch-based fast hi-polar high voltage pulse generator is proposed in this paper The proposed pulse system is made of a thyristor based-rectifier, DC link capacitor, a push-pull resonant inverter, a high voltage transformer. secondary capacitor, a high voltage IGBT & diode stacks, and a variable capacitor. The proposed system makes hi-polar high voltage sinusoidal waveform using resonance between leakage inductance of the transformer and secondary capacitor and transfers energy to output load at maximum of the secondary capacitor voltage. Compared to previous hi-polar high voltage pulse power supply using nonlinear transmission line, the proposed pulse power system using only semiconductor switches has simple structure and gives high efficiency

• 전자공학회논문지C
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• 제34C권4호
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• pp.26-35
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• 1997

This paper proposes a multi-bit $\Sigma\Delta$ modulator arcitecture which eliminates signal clipping problem. To avoid signal clipping, the output values of intgrators are monitored and modified by a reference value. This oepration is recorded as a digital code to restore actual signal value. Due to the digital code, the substraction of feedback value from the multi-bit quantizer can be calculated by a digital adder and this simplifies dAC operation making the accurate DAC of conventional multi-bit $\Sigma\Delta$ modulator scheme unnecessary. These features make N-th modulator can be implemented by sharing an integrator among N stages to decrease the required chip area. As an experimental example, a 4th order .sum..DELTA. modulator with oversampling ratio of 64 was simulated to show over 130 DB SNR at rail-to-rail input sinusoidal signal.

• 센서학회지
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• 제3권1호
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• pp.46-53
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• 1994

본 논문에서는 FA용 센서 중의 하나인 고주파 발진형 근접 센서 시스템을 CMOS를 이용하여 설계하였다. 금속 물체의 원근에 따라 발생되는 크기가 다른 두 정현파를 전파정류부와 평활회로부를 통하여 DC 전압으로 전환하여 정전류회로의 출력단에 전류를 흐르게 한다. 슈미트 트리거를 사용하여 전압 레벨의 노이즈를 제거한다. 이를 통하여 고주파 발진형 근접 센서 시스템이 소형, 경량화, 저 소비 전력의 이점을 갖도록 하였다.

• 한국산업융합학회 논문집
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• 제6권1호
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• pp.3-10
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• 2003

Application of matrix converter to vector control of induction motor using simplified Venturini algorithm which is capable of achieving the maximum output voltage is developed. This algorithm simplifies the control algorithm and therefor reduces the digital implementation time. Matrix converter is used as voltage-referenced voltage fed vector controlled induction motor drive. This paper describes the performance of vector controlled induction motor with four quadrant capability employing a matrix converter power circuit. The advantage of this system over the conventional rectifier-inverter arrangement are capability for regeneration into the utility, sinusoidal supply currents and minimum passive components. The steady-state and transient performance of the induction motor drive under the vector control technique is demonstrate with simulation and experiment results.