• Title/Summary/Keyword: K-linearization

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Optimal Linearization-Based Robust Controller Design for Underwater Glider (수중글라이더의 최적선형화 모델기반 강인제어기 설계)

  • Moon, Ji Hyun;Lee, Ho Jae
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.12
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    • pp.2023-2029
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    • 2016
  • This paper addresses a robust controller design technique for a nonlinear underwater glider with disturbances. We consider the buoyancy and pitching moment as control inputs, which generate additional nonlinearity on the plant dynamics. To deal with the nonlinearity, we utilize the optimal linearization technique. The conditions for the optimal linearization and the controller design are formulated in terms of matrix inequalities. The effectiveness of the proposed method is demonstrated through a simulation.

A Study on Linearization of Intermodulation Distortion for WCDMA

  • Jeon, Joong-Sung;Kim, Dong-il
    • Journal of Navigation and Port Research
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    • v.28 no.2
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    • pp.149-154
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    • 2004
  • A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping, because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance, a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth Experimental results are presented for IMT-2000 frequency band The center frequency of the feedforward amplifier is 2140MHz with 60MHz bandwidth When the average output power of feedforward amplifier is 20 Watt, the intermodulation cancellation performance is more than 28dB. In this case, the output power of feedforward amplifier reduced 3.5dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7% for multicarrier signals.

Advanced Control of Three-Phase Four-Wire Inverters using Feedback Linearization under Unbalanced and Nonlinear Load Conditions (불평형 비선형 부하시 궤환선형화 기법을 이용한 3상 4선식 인버터의 제어 성능 개선)

  • Vo, Nguyen Qui Tu;Lee, Dong-Choon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.18 no.4
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    • pp.333-341
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    • 2013
  • In this paper, a feedback linearization control is proposed to regulate the output voltages of a three-phase four-wire inverter under the unbalanced and nonlinear load conditions. First, the nonlinear model of system including the output LC filters is derived in the d-q-0 synchronous reference frame. Then, the system is linearized by the multi-input multi-output feedback linearization. The tracking controllers for d-q-0-components of three-phase line-to-neutral load voltages are designed by linear control theory. The experimental results have shown that the proposed control method gives the good performance in response to the load conditions.

Linearization of Nonlinear Random Vibration Beam by Equivalent Energy Method (비선형 불규칙 진동 보의 등가에너지법에 의한 선형화)

  • Lee, Sin-Young;Cai, G.Q.
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.71-76
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    • 2008
  • Nonlinear dynamic system under random excitation was analyzed by using stochastic method. A linearization method was used in order to linearize non-linear structural characteristics but the parametric excitation was used as it was given. An equivalent energy method which equalizes the expectation value of energy of the original nonlinear system and that of quasi-linearized system was proposed. Ito's differential rule was applied to obtain steady state moments. Quasi-linearization coefficients can be obtained the iterative calculation of linearization scheme and steady state moments. Monte Carlo simulation was used to verify the results of the proposed method. Nonlinear vibration of a slender beam was analyzed in this research. The analysis results were compared with Monte Carlo simulation result and showed good agreement. As the spectral density of the given excitation increased, the analysis results showed the better agreement with Monte Carlo simulation.

Periodic solutions of the Duffing equation

  • Tezcan, Jale;Hsiao, J. Kent
    • Structural Engineering and Mechanics
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    • v.30 no.5
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    • pp.593-602
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    • 2008
  • This paper presents a new linearization algorithm to find the periodic solutions of the Duffing equation, under harmonic loads. Since the Duffing equation models a single degree of freedom system with a cubic nonlinear term in the restoring force, finding its periodic solutions using classical harmonic balance (HB) approach requires numerical integration. The algorithm developed in this paper replaces the integrals appearing in the classical HB method with triangular matrices that are evaluated algebraically. The computational cost of using increased number of frequency components in the matrixbased linearization approach is much smaller than its integration-based counterpart. The algorithm is computationally efficient; it only takes a few iterations within the region of convergence. An example comparing the results of the linearization algorithm with the "exact" solutions from a 4th order Runge- Kutta method are presented. The accuracy and speed of the algorithm is compared to the classical HB method, and the limitations of the algorithm are discussed.

Stabilization of Underwater Glider by Buoyancy and Moment Control: Feedback Linearization Approach (부력 및 모멘트 제어를 이용한 수중글라이더의 안정화: 피드백 선형화 접근법)

  • Jee, Sung Chul;Lee, Ho Jae;Kim, Moon Hwan;Moon, Ji Hyun
    • Journal of Ocean Engineering and Technology
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    • v.28 no.6
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    • pp.546-551
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    • 2014
  • This paper addresses a feedback linearization control problem for the nonlinear dynamics of an underwater glider system. We consider the buoyancy and moment as control inputs, which come from the mass variation and elevator control, respectively. Moment-to-force coupling increases the nonlinearities, which make the controller design difficult. By using a feedback linearization technique, we convert the nonlinear underwater glider to an equivalent linear model and design a linear controller. The controller for the equivalent converted linear system is designed using sufficient conditions in terms of linear matrix inequalities. Then, the control input of the nonlinear model of an underwater glider is formulated from the linear control input. An experimental examination is implemented to verify the effectiveness of the proposed technique.

High-Performance Control of Three-Phase Four-Wire DVR Systems using Feedback Linearization

  • Jeong, Seon-Yeong;Nguyen, Thanh Hai;Le, Quoc Anh;Lee, Dong-Choon
    • Journal of Power Electronics
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    • v.16 no.1
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    • pp.351-361
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    • 2016
  • Power quality is a critical issue in distribution systems, where a dynamic voltage restorer (DVR) is commonly used to mitigate the voltage disturbances for loads. This paper deals with a nonlinear control for the three-phase four-wire (3P-4W) DVR under a grid voltage unbalance and nonlinear loads in the distribution system, where a novel control scheme based on the feedback linearization technique is proposed. Through feedback linearization, a nonlinear model of a DVR with a PWM voltage-source inverter (VSI) and LC filters is linearized. Then, the controller design of the linearized model is performed by applying the linear control theory, where the load voltages are kept constant by controlling the d-q-0 axis components of the DVR output voltages. To keep the load voltage unchanged, an in-phase compensation strategy is employed, where the load voltages are recovered to be the same as the previous voltage without a change in the magnitude. With this strategy, the performance of the DVR becomes faster and more stable even under unbalanced source voltages and nonlinear loads. The validity of the proposed control strategy has been verified by simulation and experimental results.

A Study on 800 MHz 1W Cartesian Feedback Linearized Power Amplifier for TETRA Signals (TETRA 신호를 위한 800 MHz 대역 1W 급 Cartesian feedback 선형 전력 증폭기에 관한 연구)

  • Oh, Duk-Soo;Kim, Ji-Yeon;Chun, Sang-Hyun;Kim, Jong-Heon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.7 no.4
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    • pp.76-85
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    • 2008
  • In this paper, a 800 MHz 1 W cartesian feedback linearized power amplifier is designed and fabricated for TETRA handset application. For amplification of TETRA signal with 200 kHz narrow bandwidth, amplifier linearization performance of more than 30 dBc is improved through the cartesian feedback linearizer at the offset Sequency of ${\pm}25$ kHz. It is clear that the linearization performance is affected by imbalance of gain and phase between I/Q signals and also DC offset. The linearization performance can be maximized by the compensation of those influences. Cartesian feedback is suitable for a liearization technique of narrow band signal with QAM and another modulation signals, as well.

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