• Title, Summary, Keyword: feedforward method

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The Study on the Linearizer Using Feedforward Method (Feedforward 방식을 이용한 선형화기에 관한 연구)

  • 정종한;박천석
    • Proceedings of the IEEK Conference
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    • pp.337-340
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    • 2000
  • In this paper, I compared some characteristics between HPA and LPA using Feedforward method. Feedforward method is known for best IMD correction. HPA generated 46.5㏈c at 45.5㏈m output power. But, using feedforward linearing method, I could improve IMD to 67.17㏈c at the same output power. IMD could be improved 20.67㏈ at 45.5㏈m output power. I measured average power, IMD, total current, and efficiency of two amplifier at many different power levels. I could get about 70d3c IMD using feedforward method.

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Adaptive Control Method for a Feedforward Amplifier

  • Kang, Sang-Gee;Yi, Hui-Min;Hong, Sung-Yong
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • pp.108-112
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    • 2003
  • A feedforward amplifier, which is composed of several components, is an open loop system. Therefore, feedforward amplifiers are apt to deteriorate the performance according to the environmental changes even though the cancellation performance and the linearization bandwidth of feedforward systems are superior to other linearization methods. A control method is needed for maintaining the original performance of feedforward amplifiers or to keep the performance within a little error bounds. In this paper, an adaptive control method, which has a good convergence characteristic and is easy to implement, is suggested. The characteristics of the suggested control method compare with the characteristics of other control methods and the simulation results are presented.

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A Design of Sliding Mode Observer for SISO Linear Systems (단일 입.출력 선형시스템에 대한 슬라이딩 모드 관측기 설계)

  • 문형장;권성하;박승규;정은태
    • 제어로봇시스템학회:학술대회논문집
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    • pp.24-24
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    • 2000
  • This paper proposes a design method of sliding mode observer for SISO linear systems with a disturbance input. We first construct an observer with a constant gain matrix, a feedforward injection map and an external feedforward compensation signal input. Using the second Lyapunov method, we present a sufficient condition for the existence of sliding mode observer. The proposed observer guarantees that the state error trajectories enter a certain region in finite time and remain inside thereafter.

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Feedforward Compensation Method of Output Voltage with 3Phase AC/DC PWM Converter on DC Distribution System for Improved Response (응답성 향상을 위한 직류배전용 3상 AC/DC PWM 컨버터 출력전압 전향보상 기법)

  • Choi, Hyeong-Jun;Lee, Chun-Bok;Hong, Seok-Jin;Hyun, Seung-Wook;Won, Chung-Yuen
    • Proceedings of the KIPE Conference
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    • pp.516-517
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    • 2015
  • This paper proposes the feedforward compensation method of output voltage with 3phase AC/DC PWM converter on DC distribution system for improved response. AC/DC PWM converter on DC distribution is required power supply of high quality because of renewable energy sources and load links. In general, Feedforward compensation method of 3phase AC/DC PWM converter receives the sensor input to the output current, load power. Resulting, error of the sensing values and communication cause time delay. Therefore, Feedforward compensation method through only the output voltage is proposed in this paper. The feedforward compensation method through only the output voltage can be applied to the two-level AC/DC PWM converters, as well as multi-level converter or inverter.

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Improvement of Transient Performance of Synchronous Generator using Feedforward Controller (피드포워드 제어기를 사용한 동기발전기의 과도특성 개선)

  • An, Young-Joo
    • The Transactions of the Korean Institute of Electrical Engineers P
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    • v.67 no.2
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    • pp.57-62
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    • 2018
  • A brush-less type synchronous generator driven by an internal-combustion engine is used for emergency electric source. These types of generators have to maintain a certain range of output voltage even under the sudden load change conditions such as full load application and removal. This paper describes a method for suppressing the output voltage of a synchronous generator that operates excessively when the load fluctuates. The method used in this paper is a feedforward control method in which the main voltage control consists of a feedback loop using a typical PID controller and the load current is detected as a disturbance element and compensated directly. A feedforward system is constructed in which the load current is regarded as disturbance, and the appropriate feedforward controller configuration and parameters are found through simulation. Finally, it can be seen through the experiment that the feedforward control is performed properly. It can be seen that the generator terminal voltage is recovered to the steady state in a short period of time as compared with the existing PID control method even when the entire load of the generator is changed.

Adaptive Control Method for a Feedforward Amplifier (피드포워드 증폭기의 적응형 제어 방법)

  • Kang, Sang-Gee;Yi, Hui-Min;Hong, Sung-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.2
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    • pp.127-133
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    • 2004
  • A feedforward amplifier, which is composed of several components, is an open loop system. Therefore, feedforward amplifiers are apt to deteriorate its performance according to the environmental changes even though the cancellation performance and the linearization bandwidth of feedforward systems are superior to other linearization methods. A control method is needed for maintaining the original performance of feedforward amplifiers or to keep the desired performance within a little error bounds. In this paper, an adaptive control method using the steepest descent algorithm, which has a good convergence characteristic and is easy to implement, is suggested. The characteristics of the suggested control method compare with the characteristics of other control methods and the simulation results are presented.

A Simultaneous Experimental Disturbances Identification of Gyro Stabilized 2-Axes Gimbal System for Disturbance Feedforward Compensation Control (2-축 자이로 안정화 김발 시스템의 외란보상 앞먹임 제어를 위한 실험적 2-축 외란 동시 식별)

  • Yeo, Sung Min;Kang, Min Sig
    • Journal of the Korea Institute of Military Science and Technology
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    • v.21 no.4
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    • pp.508-519
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    • 2018
  • This paper concerns on stabilization control of a gyro-stabilized 2-axes gimbal system which is mounted on a moving vehicles such as automobiles, armored vehicles, ships, flying vehicles, etc. A target image acquisition system is attached on the inner gimbal, and the gimbal systems are required to retain high stabilization accuracy in the absolute coordinate in order to provide fine target image while vehicle is moving. The stabilization control performance is hardly depended upon disturbance rejection ability of control, and disturbance feedforward compensation is effective because feedforward compensation reduce the amount of disturbance before the disturbance disturbs the systems. This paper suggests an experimental method which can estimate system parameters and disturbance torques by using 3-axes accelerometer mounted on the inner gimbal. Furthermore, a simple disturbance identification method which can be applied to any slanted base conditions has been suggested to identify mass unbalance vector and friction torques of each gimbal simultaneously. By using the estimated parameters, a feedforward compensation has been applied to the gyro-stabilized 2-axes gimbal system. The experimental results showed that the feedforward compensation based on the identification method suggested is effective to improve stabilization performances.

Decoupling Control of Three-tank Liquid Level Systems Based on Feedforward Compensation (Feedforward 보상에 근거한 3개의 탱크 액체 레벨 시스템의 통제 분리)

  • Shi, Xue-Wen
    • 전자공학회논문지 IE
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    • v.45 no.3
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    • pp.36-41
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    • 2008
  • By considering decoupling between loops as a kind of measurable disturbance, a steady-state decoupling method based on feedforward compensation is proposed for a three-tank liquid level system often encountered in practical process control. In addition, the three-tank liquid level system's dynamic model with structure of two-input and two-output is presented according to its working principle. Finally simulation experiments given in C++Builder language demonstrate the effectiveness of the proposed method.

Voltage Feedforward Control with Time-Delay Compensation for Grid-Connected Converters

  • Yang, Shude;Tong, Xiangqian
    • Journal of Power Electronics
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    • v.16 no.5
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    • pp.1833-1842
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    • 2016
  • In grid-connected converter control, grid voltage feedforward is usually introduced to suppress the influence of grid voltage distortion on the converter's grid-side AC current. However, owing to the time-delay in control systems, the suppression effect of the grid voltage distortion is seriously affected. In this paper, the positive effects of the grid voltage feedforward control are analyzed in detail, and the time-delay caused by the low-pass filter (LPF) in the voltage filtering circuits and digital control are summarized. In order to reduce the time-delay effect on the performance of the feedforward control, a voltage feedforward control strategy with time-delay compensation is proposed, in which, a leading correction of the feedforward voltage is used. The optimal leading step used in this strategy is derived from analyzing the phase-frequency characteristics of a LPF and the implementation of digital control. By using the optimal leading step, the delay in the feedforward path can be further counteracted so that the performance of the feedforward control in terms of suppressing the influence of grid voltage distortion on the converter output current can be improved. The validity of the proposed method is verified through simulation and experiment results.

Automatic adjustment of feedforward signal in boiler controllers of thermal power plants

  • Egashira, Katsuya;Nakamura, Masatoshi;Eki, Yurio;Nomura, Masahide
    • 제어로봇시스템학회:학술대회논문집
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    • pp.83-86
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    • 1995
  • This paper proposes an auto-tuning method of feedforward signal in boiler control of thermal power plants by using the neural network. The neural network produces an optimal feedforward signal by tuning the weights of the network. The weights are adapted effectively by using the teaching signal of PI control output. The proposed method was evaluated based on a detailed simulator which expressed non-linear characteristics of the 600 MW actual thermal power plant at load chaning operations, showed effectiveness in the learning of the weights of the neural network, and gave an accurate control performance in the temperature control of the system. Through the evaluation, the proposed method was proved to be effectively applicable to the actual thermal plants as the automatic adjustment tool.

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