• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부A
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• pp.117-120
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• 1998

This paper proposes a new high efficiency single-phase AC-DC boost converter for power factor correction. Lossless commutation circuit is interposed in the proposed converter for soft-switching. Due to this commutation circuit, the converter operates in 9 mode. In spite of changing input voltage and load, It attracts a constant DC output voltage because of the PWM control scheme using both the output voltage feedback and the input voltage feedforward. The converter is suitable for high power applications and operates in continuous conduction mode. In this paper, a 2.4[kW] converter is designed and simulated.

• 전력전자학회논문지
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• 제3권3호
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• pp.214-221
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• 1998

직접 구동용 브러시 없는 직류전동기(BRUSHLESS direct drive motor : BLDD motor)의 강인한 위치제어를 위해 신경망을 사용하여 접근하는 새로운 제어방식이 소개된다. 전향 신경망이 추가된 선형 2차 제어기는 AC서보의 객체지향 방법을 사용함으로서 대략적으로 선형화 되어지는 강인한 BLDD 모터 시스템을 얻기 위해 사용된다. 구동 상태의 온-라인 위상에서 학습되는 이 신경망은 전향신호와 오차 역 전파법(Back-Propagation Method)에 의해 구성된다. 총 노드의 수가 8개이기 때문에 이 시스템은 일반적인 마이크로 프로세서에 의해 쉽게 실현될 수 있다. 일반적인 작동중, 입출력 응답은 표본화되어지고 가중치는 매개변수 또는 부하 토크의 능한 변이를 적용하기 위해 각 표본주기에서 오차 역 전파법에 의해 학습된다. 그리고, 상태공간에서 시스템 분석은 상태 궤환 이득을 얻기 위해 체계적으로 실행했다. 또한, 강인성은 전반적인 시스템응답에 영향력을 주지 않고 얻어진다.

• Journal of Power Electronics
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• 제16권1호
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• pp.38-47
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• 2016

This paper presents DG based droop controlled parallel inverter systems with virtual impedance considering the unequal resistive-inductive combined line impedance condition. This causes a reactive power sharing error and dynamic performance degradation. Each of these drawbacks can be solved by adding the feedforward term of each line impedance voltage drop or injecting the virtual inductor. However, if the line impedances are high enough because of the long distance between the DG and the PCC or if the capacity of the system is large so that the output current is very large, this leads to a high virtual inductor voltage drop which causes reductions of the output voltage and power. Therefore, the line impedance voltage drops and the virtual inductor and resistor voltage drop compensation methods have been considered to solve these problems. The proposed method has been verified in comparison with the conventional droop method through PSIM simulation and low-scale experimental results.

• Journal of Electrical Engineering and Technology
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• 제13권3호
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• pp.1265-1274
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• 2018

This paper proposes a virtual flux (VF) and positive-sequence power based control strategy to improve the performance of grid-interfaced three-phase voltage source converters against unbalanced and distorted grid conditions. By using a second-order generalized integrator (SOGI) based VF observer, the proposed strategy achieves an AC voltage sensorless and grid frequency adaptive control. Aiming to realize a balanced sinusoidal line current operation, the fundamental positive-sequence component based instantaneous power is utilized as the control variable. Moreover, the fundamental negative-sequence VF feedforward and the harmonic attenuation ability of a sequence component generator are employed to further enhance the unbalance regulation ability and the harmonic tolerance of line currents, respectively. Finally, the proposed scheme is completed by combining the foregoing two elements with a predictive direct power control (PDPC). In order to verify the feasibility and validity of the proposed SOGI-VFPDPC, the scenarios of unbalanced voltage dip, higher harmonic distortion and grid frequency deviation are investigated in simulation and experimental studies. The corresponding results demonstrate that the proposed strategy ensures a balanced sinusoidal line current operation with excellent steady-state and transient behaviors under general grid conditions.

• 전력전자학회논문지
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• 제21권4호
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• pp.364-372
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• 2016

In this paper, a voltage controller for the seamless transition of a grid-connected inverter for ESS is proposed. The single-phase inverter is operated as a current controller when the grid is connected and as a voltage controller in the stand-alone mode when the grid is disconnected. Generally, in the case of grid recovery, the overcurrent may flow into the system because of the mismatch phase between the inverter output and grid voltages. The proposed controller resolves the overcurrent problem through phase delay problems with initial value feed-forward control of the integrator when the grid voltage is restored. The effects of the control method are simulated through PSIM, and the usefulness of the control method is verified through experiments.

• 전기학회논문지
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• 제58권7호
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• pp.1405-1410
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• 2009

Output voltage of a DC/DC power converter system is likely to be distorted if variable loads exist in the output terminal. This paper presents a new disturbance observer(DOB) approach to maintain a robust regulation of the output voltage of a boost type DC/DC converter. Unlike the buck-type converter case, the regulation problem of the boost converter is very complicated by the fact that, with respect to the output voltage to be regulated, the system is non-minimum phase. Owing to the non-minimum phase property the classical DOB approach has not been applied to the boost converter. Motivated by a recent result on the application of DOB to non-mimimum phase system, an output feedback control law is proposed by using a parallel feedforward compensator. Simulation results using the Simulink SimPowerSystems prove the performance of the proposed controller against load variation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.296-298
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• 2009

Ac-dc 싸이리스터 컨버터에서 전류기준값의 부호가 변화할 경우에 적분항 초기값을 통해 전류제어 과도특성을 개선하는 연구가 있었다. 이 논문에서는 전류기준값의 기울기에 변화가 있을 때 그 변화를 일으키기 위한 전압을 계산하고 그 값을 점호각 $\alpha$로 환산하여 시스템에 적용시켜 변곡점 부근에서의 전류제어 특성을 개선하는 방법을 제시하였다. 또한 전류기준값에 노이즈가 포함된 경우 LPF 유/무에 따른 특성변화와 노이즈가 포함되지 않은 경우 LPF 유/무에 따른 특성변화를 관찰하였다.

• Nuclear Engineering and Technology
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• 제26권3호
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• pp.420-424
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• 1994

가압경수로형 원자력발전소의 저출력 및 과도상태에서의 개선된 증기발생기 수위 제어 방식을 제시하였다. 수축 및 팽창 현상에 의한 수위의 요동을 줄이기 위해 기존의 비례·적분 제어기에 증기발생기 압력 및 급수온도를 고려한 앞먹임 보상부를 첨가하였다. 원전 훈련용 시뮬레이터를 이용하여 시뮬레이션을 수행한 결과 기존방식에 비해 적은 수위오차, 훨씬 빠른 진정시간을 얻을 수 있었다. 제시된 알고리즘은 구현이 용이하고 실제 적용도 가능하리라 판단된다.

• 유공압시스템학회논문집
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• 제8권2호
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• pp.23-28
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• 2011

This paper investigates the motion control of a hydraulic motor-load system using the Simple Adaptive Control (SAC) method. The plant transfer function has been modelled mathematically. The open-loop responses have been obtained experimentally in order to identify the design parameters of transfer function. The hydraulic motor-load system has been modelled using the 3D CAD and imbedded in the hydraulic circuit simulation program to verify the overall performance. The experimental results confirm that the SAC method gives a good tracking performance compared to the PID control.

• 유공압시스템학회논문집
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• 제4권2호
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• pp.21-27
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• 2007

This paper deals with the issue of trajectory tracking control of a clamping cylinder for injection moulding machine, which is directly driven by speed controlled hydraulic pump in combination with AC servomotor. As a fundamental step prior to tracking controller design, feedback control system is developed by implementing a position control loop parallel with a system pressure control loop. A sliding mode controller combining velocity feedforward scheme is developed for enhancing the tracking performance. Consequently a significant reduction in tracking error is achieved for both position and pressure control applications.