• 대한전기학회논문지
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• 제39권5호
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• pp.478-484
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• 1990

An automatic tuning method of a PID controller which is used for single input single output processes is proposed. In the proposed tuning method, the frequency response data model is adopted along with the performance index which is an integral of time weighted square error between reference model and process frequency response data model for tuning. This method is easier to retune when either the process dynamics is changed or the reference model is changed. Finally, an example is provided to show the usefulness of the method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.678-680
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• 1998

Based on fuzzy logic algorithm this paper constructed fuzzy logic controller for automated vehicles. For passenger's convenience especially comfortability controller need to reduce the frequency of input variable's changing. So we established membership functions for comfortability as mil as speed following. It made possible to control comfortability directly. To demonstration the efficiency of fuzzy logic controller, we carried out simulation with a Automobile's transfer function. First, we designed the PID controller by using Ziegler-Nichols tunning method. Second, we calculated time response for each controller, then we compared the speed patterns of fuzzy controlled system and PID controlled system. Also we compared the difference of input variable. By comparing two controller's response, we can confirm the merit of fuzzy controller about comfortability. Fuzzy controller can reduce input changing frequency.

• 전력전자학회논문지
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• 제8권2호
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• pp.116-127
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• 2003

본 논문에서는 UPS 인버터의 성능 개선을 위하여 출력측 LC 필터의 커패시터 전압과 전류의 2중 제어루프를 구성하고, 2중 제어루프에 디지털 제어시스템을 채택하였다 또한, 디지털 제어기의 연산지연시간을 보상하기 위하여 이러한 연산지연시간을 인버터 플랜트의 고유한 파라미터로 가정하고, 플랜트 모델에 포함시켜 모델링 하였다. UPS 인버터 출련전압의 과도상태 응답특실을 개선하고, 파라미터 변동에 강인한 특성을 얻기 위하여 2중 제어루프에서 내부 전류 제어루프는 내부 모델 제어기를 제안하였다. UPS 인버터 출력전압의 0의 정상상태 오차를 얻기 위하여 외부 전압 제어루프는 비례 제어기와 공진 제어기를 병렬로 연결한 비례-공진 진압제어기를 제안하였다.

• 전자공학회논문지SC
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• 제44권1호
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• pp.1-11
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• 2007

본 논문에서는 UPS 인버터의 성능 개선을 위하여 출력측 LC 필터의 커패시터 전압과 전류의 2중 제어루프를 구성하고, 2중 제어루프에 디지털 제어시스템을 설계하였다. 또한, 디지털 제어기의 연산지연시간을 보상하기 위하여 이러한 연산지연시간을 인버터 플랜트의 고유한 파라미터로 가정하고, 플랜트 모델에 포함시켜 모델링 하였다. UPS 인버터 출력전압의 과도상태 응답특성을 개선하고, 파라미터 변동에 강인한 특성을 얻기 위하여 2중 제어루프에서 내부 전류 제어루프는 내부 모델 제어기를 제안하였다. UPS 인버터 출력전압의 0의 정상상태 오차를 얻기 위하여 외부 전압 제어루프는 비례 제어기와 공진 제어기를 병렬로 연결한 비례-공진 전압제어기를 제안하였다. 또한, 사용자에게 쉽게 UPS의 동작 상태를 표시하기 위하여 그래픽 사용자 인터페이스를 이용한 UPS의 모니터링 시스템을 구현하였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.106-108
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• 2008

This paper deals with the design for speed controller to drive PMSM by matrix converter without DC-link circuit as the power conversion system of AC servo motor drive. To design the speed controller of PMSM drive, the closed-loop transfer function of speed controller is calculated and then the frequency-domain response characteristics are analyzed by bode plot using Matlab. Based on the results by bode plot, the speed control gains are determined. As the real effects of controller designed in the frequency-domain display in the time-domain, the performance of speed controller is confirmed by the step response of speed controller. The design examples are shown and its validity of the design method mentioned in the paper is verified through PSIM simulation.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1439-1443
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• 2007

In this paper, vibration reduction techniques of a voice coil motor (VCM) actuator are presented for AFM imaging system. The damping coefficient of the actuator driven by VCM with a flexure hinge is quite low and it cause the about 30dB peak amplitude response at the resonance frequency. To decrease this peak response, we design and apply elliptical band-stop filters to xy and z axis VCM actuator. Frequency response of each actuator with filter is measured to verify the effect of the filters. As a sensor, capacitive sensor is used. Vibration reduction rate of the xy actuator with the filter is also measured while real AFM scanning condition. As another method, closed loop control with the capacitive sensor is applied to the xy axis actuator to add an electrical damping effect and vibration reduction rate measured. These vibration reduction rates with each method are compared. In the case of z axis actuator, the frequency response of force (gap) control loop is measured. For comparison, the frequency response using a conventional PID controller is also obtained. Finally, the AFM image of a standard grid sample is measured with the designed controller to analyze the effect in the AFM imaging.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 B
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• pp.728-730
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• 1998

The control valve positioner is a high gain plain proportional controller which measures the valve stem position and compares it to its setpoint which is the primary controller output. The positioner in effect is the cascade slave of the primary controller. In order for a cascade slave to be effecttive, it must be fast enough compared to the speed of its set point change. This paper describes the positioner transfer function and its effect on the entire control loop characteristic based on the simulation results. The result showed that the control valve and positioner determined the gain and phase angle in the high frequency range, while the primary controller and process determined those of the low frequency range. We can also anticipate the combined characteristics in the whole frequency range when each element's frequency response is known.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.99-104
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• 2001

Discrete-time controller design is proposed using feedback system identification in frequency domain. System Stability imposed by a new controller is checked in the function of a conventional closed-loop system, instead of a poorly modeled plant due to non-linearity and disturbance as well as unstable components, etc. The stability of the system is evaluated in view of Popov criterion. All the equations are formulated in the framework of the discrete-time system. Simulation results are shown on the plant with input saturation components, DC disturbance and a pure integration.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집B
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• pp.664-669
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• 2001

Continuous-time controller design is proposed using feedback system identification in frequency domain. System stability imposed by a new controller is checked in the function of a conventional closed-loop system, instead of a poorly modeled plant due to non-linearity and disturbance as well as unstable components, etc. The stability of the system is evaluated in view of Nyquist stability. All the equations are formulated in the framework of the discrete-time system. Simulation results are shown on the plant with input saturation and DC disturbance.

• 조명전기설비학회논문지
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• 제22권9호
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• pp.88-93
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• 2008

본 논문에서는 저차 근사모델에 대한 필터 보상형 PID 제어기의 주파수 전달함수 합성법을 제안한다. 제안된 방식은 주어진 주파수응답 경계조건에 맞는 필터 보상형 PID 제어기를 포함한 루프 주파수 전달함수의 합성에 의해 재배열된 일차연립방정식으로부터 PID 파라미터 벡터에 대한 최소 정규해를 결정하는 방식이다. 그리고 제안된 방식의 효율성을 입증하기 위한 예제로 충주 수력발전소의 수차속도제어계가 주어진다.