• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.527-530
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• 1989

In order to reduce harmonic contents in the inverter output, various PWM ( pulse with modulation ) techniques have been utilized. This paper suggests a single phase inverter with 4-level output and its PWM control scheme. The proposed 4-level output inverter shows better performence than the 3-level output one in respects of the current error and the switching frequency.

• Journal of Power Electronics
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• 제16권2호
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• pp.675-684
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• 2016

This paper presents a new stand-alone wind-based induction generator system with constant frequency and adjustable output voltage. The proposed generator consists of a six-phase cage-rotor induction machine with two separate three-phase balanced stator windings and a three-phase space vector pulse width modulation inverter that operates as a static synchronous compensator (STATCOM). The first stator winding is fed by the STATCOM and used to excite the machine while the second stator winding is connected to the generator external load. The main frequency of the STATCOM is determined to be constant and equal to the load-requested frequency. The generator output frequency is independent of the load power demand and its prime mover speed because the frequency of the induced emf in the second stator winding is the same as this constant frequency. A sliding mode control (SMC) is developed to regulate the generator output voltage. A second SMC is used to force the zero active power exchanged between the machine and the STATCOM. Some simulation and experimental results are presented to prove the validity and effectiveness of the proposed generator system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.269-275
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• 1997

This paper presents real time digital signal processor(DSP) control of UPS system feeding processor(DSP) control of UPS system feeding nonlinear loads to provide sinusoidal inverter output voltage. The control scheme is composed of an rms voltage compensator, the load current harmonics feed-forward loop for the cancellation of output voltage harmonics, and the output voltage harmonics feedback loop for system stability. The controller employs a Texas Instruments TMS320C40GFL50 DSP.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 추계학술대회 논문집
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• pp.279-285
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• 2007

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.288-291
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• 2007

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.110-112
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• 2007

Output voltage waves of a DC/AC inverter system are likely to be distorted if variable loads e.g. motors or rectifiers exist in the output terminal. This paper designs a disturbance observer-based PI controller for a single-phase inverter system that is robust against load changes. In this paper, we regard the output voltage changes due to various loads as disturbances of the control system, Then we design a disturbance observer for estimation of the disturbances caused by the load current and any other error sources (such as parameter uncertainties and model mismatches etc.). In order to test the performance of the proposed control law, simulation studies are carried out for a single-phase inverter system using SimPowerSystems of Matlab Simulink. Compared to a simple PI control, the disturbance observer-based controller shows enhanced performance in transient responses for step load changes.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.280-281
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• 2018

The methods for adjusting the output voltage as well as the heater temperature of a single-phase inverter for the heat treatment are proposed. The output voltage of the single-phase inverter is limited to 60 V for safety. The time constant of heater temperature is much higher than that of the output voltage. The stability may be deteriorated due to such large time constant difference. In order to ensure the stability, a hysteresis on/off control method for the heater temperature control is used. The performances for the proposed methods are verified with the experiments.

• Transactions on Control, Automation and Systems Engineering
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• 제3권1호
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• pp.21-26
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• 2001

In this study, we propose a two degree of freedom robust output tracking control method for a class of nonlinear system. We consider hyperbolically nonminimum phase single-input single-output uncertain nonlinear systems. We also consider the case that the nominal input-state equation is differentially flat. Nominal stable state trajectory is obtained in the flat output space via the flat output. Nominal feedforward control input is also computed from the nominal state trajectory. Due to the nature of the method, the generated flat output trajectory and control input are noncausal. Robust feedback control is designed to stabilize the systems around the nominal trajectory. A numerical example is given is given to demonstrate that robust tracking is achieved.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 F
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• pp.1931-1933
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• 1998

In this paper, single-phase PWM AC to AC converter that operates with unit power factor and sinusoidal input line currents is presented. The output voltage of this converter is able to be obtain step up voltage as well as step down voltage. because the converter applies to operating method of buck-boost converter. The control of this converter is performed with PI control method. By using this control method low lipples in the output current and the voltage as well as fast dynamic response are achieved.

• 전력전자학회논문지
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• 제7권2호
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• pp.158-164
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• 2002

본 논문은 기존의 1차 예측 기법과 반복 제어기법을 이용하여 LC 필터와 정류 부하 등의 비선형 부하를 가지는 UPS 인버터의 출력전압 파형의 개선에 관한 연구이다. 기존의 1차 예측 기법은 정류부하에 대하여 우수한 특성을 가지므로 출력전류의 예측에 적합하나 정류 부하와 같은 비선형적인 부하의 정상 상태 오차를 보상하기에는 충분하지 못한 단점을 가진다. 따라서, 정상상태 오차를 최소화 할 수 있는 반복제어 기법을 적용하여 UPS 출력전압을 개선시키고자 한다. 제안된 제어기법에 대한 타당성을 시뮬레이션으로 검증하고, 이를 바탕으로 LC 필터를 가지는 3 kVA, 60 Hz UPS시스템을 제작하여 실험으로 검증한다