• Journal of Power Electronics
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• 제12권5호
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• pp.787-799
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• 2012

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.

• 조명전기설비학회논문지
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• 제23권10호
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• pp.59-68
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• 2009

유도전동기의 벡터제어는 고성능 적용에서 광범위하게 사용되고 있다. 그러나 이러한 드라이브 성능은 파라미터 변동에 의한 동조는 여전히 한계가 있다. 다양한 속도영역에서 운전하기 위하여 종래에는 PI과 같은 제어기를 보통 사용하였다. 이러한 제어기들은 이상적인 벡터제어 조건에서 광범위한 운전에 대하여 제한된 양호한 성능을 나타낸다. 본 논문은 다중 적응 제어기를 사용하여 유도전동기 드라이브의 고성능 제어를 제시한다. 이 제어기는 FAM(Fuzzy Adaptation Mechanism)에 의 해 속도제어, MFC(Model Reference Adaptive Fuzzy Control)에 의해 전류제어 그리고 ANN을 이용하여 속도추정을 수행한다. 제시한 제어 알고리즘은 FAD MFC및 ANN 제어기를 사용하여 유도전동기 드라이브 시스템에 적용한다. 제시한 제어기의 성능은 유도전동기의 파라미터를 사용하여 다양한 동작조건에서 해석으로 평가한다. 또한, 본 논문은 제어기의 효용성을 입증하기 위하여 해석결과를 제시한다.

• 한국산학기술학회논문지
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• 제17권3호
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• pp.473-479
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• 2016

본 논문은 가격이 저렴하고 친환경적이면서도 고성능, 고내구성, 구조적 단순함의 장점을 갖고 있어 최근에 폭넓은 관심을 받고 있는 스위치드 릴럭턴스 모터(SRM: Switched Reluctance Motor)의 보다 정확하고 안정적인 전류제어 방법에 대해 설명한다. 대부분의 전동기의 전류제어 방법에는 알고리즘과 제어 이득의 선정이 다른 제어기에 비해 상대적으로 간편한 PI 제어기를 이용한 방법이 주로 사용되어 왔다. 그러나 일반적인 PI 제어기는 SRM과 같이 고정자 권선의 전류 및 회전자의 위치마다 비선형적으로 파라미터가 급변하는 시스템의 경우 변하는 동작 지점마다 제어 이득을 조정해 주어야 하는 어려움이 발생한다. 본 논문에서는 비선형적으로 특성이 변하는 SRM 드라이브 시스템에 제어 성능이 우수한 자기동조 퍼지 제어기를 이용한 제어기법을 적용하여 비선형적인 파라미터의 변화에도 보다 안정적인 전류제어가 가능한 것을 보였다. 또한 Matlab/Simulink 시뮬레이션을 이용하여, SRM 드라이브의 전류제어에 PI 전류 제어기(PICC: PI Current Controller)와 자기동조 퍼지 전류 제어기(STFCC: Self-tuning Fuzzy Current Controller)를 각각 적용한 후 그 결과를 비교하였으며 제안한 자기동조 퍼지 제어기의 제어성능이 우수함을 확인하였다.

• 한국정밀공학회지
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• 제17권5호
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• pp.173-179
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• 2000

While a cutting tool is machining a workpiece at various cutting depth, the feedrate is usually selected based on the maximum depth of cut. Even if this selection can avoid power saturation or tool breakage, it is very conservative compared to the capacity of the machine tools and can reduce the productivity significantly. Many adaptive control techniques that can adjust the feedrate to maintain the constant cutting force have been reported. However, these controllers are not very widely used in manufacturing industry because of the limitations in measuring the cutting force signals. In this paper, turning force control systems based on the estimated cutting force signals are proposed. A synthesized cutting force monitor is introduced to estimate the cutting force as accurately as a dynamometer does. Three control strategies of PI, adaptive and fuzzy logic controllers are applied to investigate the feasibility of utilizing the estimated cutting force fur turning force control. The experimental results demonstrate that the proposed systems can be easily realized in CNC lathe with requiring little additional hardware.

• Journal of Electrical Engineering and information Science
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• 제1권2호
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• pp.101-108
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• 1996

A new speed controller based on the fuzzy algorithm with hierarchical structure is presented. The input variables of the controller are speed error and its derivative(change of error), where the output variable is the change of torque current command. Several comparisons were performed with conventional PI (proportional plus integral) controller and proposed controller. These controllers are applied to the laboratory model drive system with 2.2kW induction motor. Some simulation and experimental results show that the speed controller using fuzzy algorithm is more robust than the conventional PI controller.

• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.155-164
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• 2006

This paper focuses on a new optimization technique of a fuzzy logic based proportional integral (FLPI) load frequency controller by the multiple tabu search (MTS) algorithm. Conventionally, the membership functions and control rules of fuzzy logic control are obtained by trial and error method or experiences of designers. To overcome this problem, the MTS algorithm is proposed to simultaneously tune proportional integral gains, the membership functions and control rules of a FLPI load frequency controller in order to minimize the frequency deviations of the interconnected power system against load disturbances. The MTS algorithm introduces additional techniques for improvement of the search process such as initialization, adaptive search, multiple searches, crossover and restart process. Simulation results explicitly show that the performance of the proposed FLPI controller is superior to conventional PI and FLPI controllers in terms of overshoot and settling time. Furthermore, the robustness of the proposed FLPI controller under variation of system parameters and load change are higher than that of conventional PI and FLPI controllers.

• International Journal of Internet, Broadcasting and Communication
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• 제16권3호
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• pp.146-157
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• 2024

Despite numerous air mattresses marketed to prevent Pressure Ulcers (PU), none have fully succeeded due to residual pressure surpassing critical levels. We introduces an innovative medical bed system aiming at complete PU prevention. This system employs a unique 4-bar link mechanism, moving keys up and down to manage body pressure. Each of the 17 keys integrates a sensor controller, reading pressure from 10 sensors. By regulating motor input, we maintain body pressure below critical levels. Keys are equipped with a servo drive and sensor controller, linked to the main controller via two CAN series. Using fuzzy or PI/IP controllers, we adjust keys to minimize total error, dispersing body pressure and ensuring comfort. In case of controller failure, keys alternate swiftly, preventing ulcer development. Through experimental tests under varied conditions, the fuzzy controller with tailored membership functions demonstrated swift performance. PI control showed rapid convergence, while IP control exhibited slower convergence and oscillations near zero error. Our specialized medical robot bed, incorporating 4-bar links and pressure sensors, underwent testing with three controllers-fuzzy, PI, and IP-showcasing their effectiveness in keeping body pressure below critical ulcer levels. Experimental results validate the proposed approach's efficacy, indicating potential for complete PU prevention.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.177-177
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• 2000

In this paper, we propose a two-input two-output fuzzy controller to improve the performance of transient response and to eliminate the steady state error. The outputs of this controller are the control input calculated by position-type fuzzy controller and the accumulated error scaling factor. Here, the accumulated error scaling factor is adjusted on-line by fuzzy rules according to the current trend of the controlled process. To show the usefulness of the proposed controller, it is applied to several systems that are difficult to get satisfactory response by conventional PD controllers or PI controllers.

• 전자공학회논문지B
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• 제28B권11호
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• pp.941-954
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• 1991

The characteristics of a power plant changes as it operates for a long time and/or for different operating point. As a result, operators must retune gains of the controllers for better performance. In fact, skilled operators can retune the gains in reference to recorded data obtained by a test called dynamic test. The dynamic test, however, requires much time, and can be heavy burden for operators. In this paper, an expert knowledge-based auto-tuner is designed for drum-type boiler controllers of a fossil power plant using fuzzy logic. The performance of the proposed auto-tuner is shown via computer simulation and the simulation results show that the proposed auto-tuner is satisfactory for the desired performance.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2000년도 전력전자학술대회 논문집
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• pp.460-463
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• 2000

Fuzzy logic control(FLC) has been studied extensively and has been applied in various applications. The most popular control strategy takes the Fuzzy Proportional-Integral(FPI) form while systematic methods have been developed to derive the fuzzy rules and membership functions the choice of the scaling factors remains an open problem, In this paper an analytical FPI scaling factor determining method is derived based on the functional equivalence of the PI and FPI controllers. Simulation have been carried out with a brushless DC motor drive system as test-bed the obtained results drive system as test-bed the obtained results have verified that the derived method is applicable to both the initial choice and further tuning of the FPI scaling factors.