• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.212-215
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• 2004

• Journal of Industrial Technology
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• v.20 no.B
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• pp.175-182
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• 2000

In this paper, a novel speed control strategy using an acceleration feedforward compensation by the estimation of the system inertia is proposed. With the proposed method, the enhanced speed control performance can be achieved and the speed response against the disturbance torque can be improved for the vector-controller induction motor drive systems in which the bandwidth of the speed controller cannot be made large enough. The experimental results confirm the validity of the proposed strategy.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.135-146
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• 2013

This paper presents a feedforward control algorithm for the EGR and VGT systems of passenger car diesel engines. The air-to-fuel ratio and boost pressure are selected as control indicators and the positions of EGR valve and VGT vane are used as control inputs of the EGR and VGT controller. In order to compensate the non-linearity and coupled dynamics of the EGR and VGT systems, we have proposed a non-linear model-based feedforward control algorithm which is obtained from static model inversion approach. It is observed that the average modeling errors of the feedforward algorithm is about 2% using stationary engine experiment data of 225 operating conditions. Using a feedback controller including proportional-integral, the modeling error is compensated. Furthermore, it is validated that the proposed feedforward algorithm generates physically acceptable trajectories of the actuator and successfully tracks the desired values through engine experiments.

• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.215-220
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• 1999

In fabricated linear power amplifier(LPA), the third-order inter-modulation distortion(IMD) for main amplifier alone is 10.61dBc, and the IMD for LPA with predistorter and feedforward loop combined is 32.50dBc. Therefore, the IMD characteristic results an improvement of approximately 22dB. The main amplifier efficiency with single tone input is close to 30%, and the efficiency of the overall LPA with predistorter is 27.4% and predicted feedforward loop efficiency without predistorter is about 20%. Therefore, LPA with predistorter and feedforward loop combined is improved by 7.4%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.99-106
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• 2001

In this paper, an 1-Watt amplifier for IMT-2000 was designed and fabricated using feedfarward method which has the highest linearity and wide bandwidth. Since feedforward is sensitive to surroundings for example heat, input power level, time and so on, adaptive controller using micro controller is adopted. We fabricated a HPA with 35 dB gain, 40 dBm of 1-dB compression point, and utilized variable attenuator and variable phase shifter using reflection type to cancel loop signal. From the measured results, the fo11owing facts were obtained, in signal loop, main carrier over 35 dB was suppressed and error signal over 30 dB is cancelled in error loop, IMD characteristics above 60 dBc were obtained.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.84-91
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• 2003

This paper concerns on one-DOF non-rotating active magnetic bearing (AMB) system subject to base motion. In such a system, it is desirable to retain the axis within the predetermined air-gap while the base motion forces the axis to deviate from the desired air-gap. Motivated from this, an optimal acceleration feedforward control is proposed to reduce the base motion response without deteriorating other feedback control performances. Experimental results demonstrate that the proposed optimal feedforward control reduces the standard deviation of the air-gap to 29％ that by feedback control alone.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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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.

• Journal of KSNVE
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• v.4 no.4
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• pp.497-505
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• 1994

This paper presents a design scheme of the active noise absorber that consists of the feedforward and feedback controller. The feedback controller aims to increase damping for the specific acoustic mode. The feedforward controller synthesizes the input signal coherent with the primary noise source in order to attenuate the noise field in the broad frequency range. The feedforward controller is adapted to the variation of acoustic plants using the proposed algorithm which compensates the effect of feedback link. Experimental results demonstrate that the proposed method is effective for the active control of band-limited noise fields in the enclosure.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.8
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• pp.835-841
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• 2014

In this paper we propose a swing-up strategy for a single inverted pendulum. The proposed method has a feature whereby can handle the input and output constraint of a pendulum in a systematic way. For the swing-up of a pendulum, we adopt a 2-DOF control structure that combines the feedforward and feedback control. In order to generate the swing-up feedforward trajectories that satisfy the input and output constraint, we formulate the problem of generating feedforward trajectories as a nonlinear optimal control problem subject to constraints. We illustrate that the proposed method is more flexible than the existing method and provides great freedom in choosing the actuator of the inverted pendulum. Through an experiment, we show that the proposed method can swing a pendulum upward effectively while satisfying all the imposed constraints.

• Journal of Power Electronics
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• v.15 no.3
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• pp.577-586
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• 2015

The combination of voltage feedforward and feedback control is a conventional approach for correcting the power factor in single-phase ac-dc boost converters. The feedback duty ratio increases significantly with an increase of the line frequency and input inductance. Therefore, the performance of the conventional approach is highly dependent on the bandwidth of the feedback controller. As a result, the input power quality can be significantly exacerbated due to uncompensated duty ratios if the feedback controller is limited. This paper proposes an input impedance and current feedforward control method to reduce the control portion of the feedback controller. The findings in this paper are 1) the theoretical derivation and analysis of variations of line frequency and input inductance on a power factor correction approach, 2) guaranteed consistent performance in a wide range of conditions, and 3) that a low switching frequency can be utilized by the proposed method. A MATLAB/Simulink model and a 1.2kW dual boost converter are built to demonstrate the effectiveness of the proposed method.