• 전자공학회논문지
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• 제49권10호
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• pp.142-147
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• 2012

본 논문에서는 다이나믹 주파수 스케일링 (DFS) 카운터를 사용하여 코오스, 파인 조정 기능을 갖는 CMOS 듀티 사이클 보정회로를 제시한다. DFS 카운터는 디지털-아날로그 컨버터의 비트 스위칭 글리치를 감소시키기 때문에 제안하는 CMOS 듀티 사이클 보정회로의 듀티 보정 범위를 증가시키고 지터 특성을 개선한다. 제안하는 회로는 0.18-${\mu}m$ CMOS 공정을 이용하여 설계되었다. 0.5-1.5GHz의 넓은 동작 주파수와 25-75%의 넓은 듀티 사이클 보정 범위 내에서 측정된 최대 출력 듀티 사이클 에러는 ${\pm}1.1%$이다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권1호
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• pp.38-52
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• 2016

This paper describes the nonlinear dynamic motion behavior of a ship equipped with a portable dynamic positioning (DP) control system, under external forces. The waves, current, wind, and drifting forces were considered in the calculations. A self-tuning controller based on a neuro-fuzzy algorithm was used to control the rotation speed of the outboard thrusters for the optimal adjustment of the ship position and heading and for path tracking. Time-domain simulations for ship motion with six degrees of freedom with the DP system were performed using the fourth-order RungeeKutta method. The results showed that the path and heading deviations were within acceptable ranges for the control method used. The portable DP system is a practical alternative for ships lacking professional DP facilities.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2188-2190
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• 2004

This paper presents an implementation of power system stabilizer using inverse dynamic neuro controller. Traditionally, mutilayer neural network is used for a universal approximator and applied to a system as a neuro-controller. In this case, at least two neural networks are used and continuous tuning of neuro-controller is required. Moreover, training of neural network is required considering all possible disturbances, which is impractical in real situation. In this paper, Taylor Model Based Inverse Dynamic Neuro Model (TMBIDNM) is introduced to avoid this problem. Inverse Dynamic Neuro Controller (IDNC) consists of TMBIDNM and Error Reduction Neuro Model (ERNM). Once the TMBIDNM is trained, it does not require retuning for cases with other types of disturbances. The controller is tested for one machine and infinite-bus power system for various operating conditions.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2000년도 춘계학술대회논문집 - 한국공작기계학회
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• pp.629-634
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• 2000

Generally, the accuracy of motion control systems is strongly influenced by both the mechanical characteristics and servo characteristics of feed drive systems. In the fed drive systems of machine tools that consist of mechanical parts and electrical parts, a torsional vibration is often generated because of its elastic elements in torque transmission. Especially, a torsional vibration caused by the elasticity of mechanical elements might deteriorate the quick movement of system and lead to shorten the life time of the mechanical transmission elements. So it is necessary to analyze the electromechanical system mathematically to optimize the dynamic characteristics of the feed drive system. In this paper, based on the simplifies feed drive system model, radius errors due to position gain mismatch and servo response characteristic have been developed and an optimal criterion for tuning the gain of speed controller is discussed. The proportional and integral parameter gain of the feed drive controller are optimal design variables for the gain tuning of PI speed controller. Through the optimization problem formulation, both proportional and integral parameter are optimally tuned so as to compensate the radius errors by using the genetic algorithm. As a result, higher performance on circular profile tests has been achieved than the one with standard parameters.

• Journal of Power Electronics
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• 제14권5호
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• pp.980-988
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• 2014

This paper proposes an online gain tuning algorithm for a robust sliding mode speed controller of surface-mounted permanent magnet synchronous motor (SPMSM) drives. The proposed controller is constructed by a fuzzy neural network control (FNNC) term and a sliding mode control (SMC) term. Based on a fuzzy neural network, the first term is designed to approximate the nonlinear factors while the second term is used to stabilize the system dynamics by employing an online tuning rule. Therefore, unlike conventional speed controllers, the proposed control scheme does not require any knowledge of the system parameters. As a result, it is very robust to system parameter variations. The stability evaluation of the proposed control system is fully described based on the Lyapunov theory and related lemmas. For comparison purposes, a conventional sliding mode control (SMC) scheme is also tested under the same conditions as the proposed control method. It can be seen from the experimental results that the proposed SMC scheme exhibits better control performance (i.e., faster and more robust dynamic behavior, and a smaller steady-state error) than the conventional SMC method.

• 한국지능시스템학회논문지
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• 제8권5호
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• pp.29-38
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• 1998

본 논문에서는 부하외란이 발생할 경우 2지역 전력계통의 부하주파수 제어 즉, 각 지역내의 주파수 및 연계선 조류편차가 허용치 내로 신속히 수렴하도록 하기 위하여 신경회로망 자기동조 PID 제어기를 제안하였다. 시뮬레이션에 사용된 신경회로망은 입력층에 2개, 중간층에 10개, 출력층에 3개의 뉴런으로 구성하였다. 2개의 입력층 뉴런은 시스템의 오차와 오차 변화율이 입력되게 하였고 출력층은 PID 제어기의 파라미터에 해당하는 3개의 뉴런으로 구성하였다.시뮬레이션 결과 본 논문에서 제안한 신경회로망 자기동조 PID 제어기는 종래의 제어기법(Optimal, PID)보다 동특성 응답과 제어 성능이 우수한 제어기임을 알 수 있었다.

• Smart Structures and Systems
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• 제20권4호
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• pp.499-508
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• 2017

The ionic polymer-metal composite (IPMC) is an electroactive polymer material and has a promising potential as actuators for propulsion and locomotion in underwater systems. In this paper a physics based model is used to analyse the actuation dynamics of the IPMC propulsor. Moreover, proportional-integral (PI) controller is used for position control of the tip displacement of IPMC propulsor. PI parameter tuning is performed using particle swarm optimization (PSO) algorithm. Several performance indices have been used as an objective function to optimize the error of the system. Finally, the best tuning method is found out by comparing the results under various performance indices.

• 전자공학회논문지B
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• 제30B권9호
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• pp.122-132
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• 1993

In this paper, a self tuning control algorithm is proposed for the high performance drive of DC servo motor, which is adequate to the servo system having frequent load variation. In order to realization of the algorithm, the control system is developed using a fixed point high speed digital signal processor. TMS320C25. Control algorithm is composed of two parts. One is estimation law part using recursive least mean square method, the other is control law part using minimum variance control method. For the purpose of easiness of applying adaptive algorithm, developed control system is based o PC-DSP structure which can develop, debug programs and monitor the dynamic behaviors,etc. Through computer simulation and experimental results, it was verified that proposed control system could estimate system parameters and was robust to the variation of the load and as a result, was adequate to the servo motor drives.

• 전자공학회논문지S
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• 제34S권5호
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• pp.25-34
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• 1997

Relatively slow tuning speed of optical device causes the unwanted delay in high speed single-hop multiwavelength networks. To lessen the overhead, we present a channel access protocol with dynamjic message scheduling. Th eframe structure of proposed protocol adopts hybrid multiaccess scheme in which WDMA is used as a basic multiaccess technique and TDMA is used to provide subchannels within a wavelength band. This architecture has two merits : the network extention is not limited by available number of wavelengths, and the transmission delay caused by optical device tuning time can to minimize the number of tunings. It schedules messages that require same wavelength channels sequencely, so the total transmission delay is reduced by decreasement of wavelength changes. The performance of proposed protocol is evaluated through numerical analysis based on probability and queueing theory. The peformance of proposed protocol is evaluated through numerical analysis based on probability and queueing theory. The numeric results show that the peformance of proposed protocol is better than that of previous one.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.375-378
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• 1991

This paper presents a design method of synchronous generator excitation controller using self-tuning PID algorithm. Controller parameter is determined by using adaptive control theory in order to maintain optimal operation of generator under the various operating conditions. To determine the optimal parameter of controller. minimum variance algorithm using the recursive leastsquare(RLS) indentification method is adopted and the difference between the speed deviation with weighted factor and voltage deviation is used as the input signal of adaptive controller, which provides good damping and conversion characteristics. The results tested on a single machine infinite bus system verify that the proposed controller has better dynamic performances than conventional controller.