• 한국통신학회논문지
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• 제21권6호
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• pp.1480-1489
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• 1996

In ATM networks there are two methods in traffic control as schemes advancing the quality of service. One is reactive control after congestion and the other which is generally recommended, is preventive control before congestion, including connection admission control on call leel and usage parameter control, network parameter control, priority control and congestion control on cell level. In particular, usage parameter control is required for restricting the peak cell rate of bursy tracffic to the parameter negotiated at call set-up phase since the peak cell rate significantly influences the network quality of service. The scheme for progressing quality of service by usage parameter control is themethod using VSA(Virtual Scheduling Algorlithm) recommended ITU-T. The method using VSSA(Virtual Scheduling Suggested Algorlithm) in this paper is suggested by considering cell delay variation and token rate of leaky bucket, compared VSA and VSANT(Virtual Scheduling Algolithm with No Tolerance) with VSSA which polices violated cell probability of conformed peak cell rate and intentionally excessive peak cell rate. VSSA method using IPP(Interruped Poisson Process) model of input traffic source showed more quality of service than VSA and VSANT methods as usage parameter control because the suggested method reduced the violated cell probability of contformed peak cell rate and intentionally excessive peak cell rate.

• 대한전기학회논문지
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• 제39권10호
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• pp.1075-1085
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• 1990

This paper presents a new method for the optimal control of the distributed parameter systems by a decentralized computational procedure. Approximate lumped parameter models are derived by using the Galerkin method employing the Legendre polynomials as the basis functions. The distributed parameter systems, however, are transformed into the large scale lumped parameter models. And thus, the decentralized control scheme is introduced to determine the optimal control inputs for the obtained lumped parameter models. In addition, an approach to block pulse functions is applied to solve the optimal control problems of the obtained lumped parameter models. The proposed method is simple and efficient in computation for the optimal control of distributed paramter systems. Illustrative examples given to demonstrate the validity of the presently proposed method.

• Transactions on Control, Automation and Systems Engineering
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• 제2권2호
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• pp.130-135
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• 2000

A two parameter model of a single fictitious weak acid with unknown dissociation constant has been successfully applied to design a neutralization system for many multi-component acid streams. But there are some processes for which above two parameter model is not satisfactory due to poor approxmation of the nonlinearity of pH process. Here, for etter control of wide class of multi-component acid streams, a three parameter model of a strong acid and a weak acid with unknown dissociation constant is proposed. The model approximates effectively three types of largest gain variation nonlinearities. Based on this model a nonlinear pH control system is designed. Parameters can eeasily estimated since their combinations appear linearly in the model equations and nonlinear adaptive control system may also be constructed just as with the two parameter model.

• International Journal of Air-Conditioning and Refrigeration
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• 제6권
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• pp.136-147
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• 1998

An experimental facility consisting of two 3$\times$4.4$\times$2.8m rooms identical in construction is built. Each room has a control system and storage tank supplying hot water to the radiant floor heating system. The facility enables simultaneous comparison of two different control strategies each implemented in a separate room. The operating performance of three kinds of flow control scheme is tested and compared in this study: (ⅰ) conventional on-off control based on feedback from room air temperature (ⅱ) TPSC(two parameter switching control )(ⅲ) TPOC(two parameter on-off control). Results show that TPSC and TPOC using room air and surface temperature sequentially as feedback signal to control hot water supply is the better temperature regulation scheme than conventional control based on feedback from only room air temperature. They are good candidates for the room with radiant floor heating system under continuous and intermittent heating mode.

• 한국시뮬레이션학회논문지
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• 제16권2호
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• pp.37-44
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• 2007

EWMA(지수가중평균)을 사용한 제어 방법은 반도체 제조 공정의 런투런 제어 환경에서 사용되는 대표적인 제어 방법이다. EWMA 제어에서는 제어 모수 값의 선택이 제어 결과에 주된 영향을 미치기 때문에, 공정 상황에 적합한 제어 모수 값을 사용하는 것이 중요하다. 불안정적인 공정 상황에서는 변화하는 공정 상황에 적합한 값으로 EWMA 제어 모수를 동적으로 변경하면서 제어해 주는 것이 고정된 모수 값을 사용하는 EWMA 제어에 비해 효율적이다. 본 연구에서는 동적인 EWMA 제어 모수를 사용한 기존 연구들을 살펴보고 이들의 단점을 보완한 새로운 알고리즘을 제시하며, 시뮬레이션을 통해 우수한 수행 결과를 확인하였다.

• 전기의세계
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• 제19권2호
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• pp.21-23
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• 1970

Necessary conditions of optimal distributed parameter control systems, Hamiltons coanonical equations, welerstress condition, transversality condition and boundary condition are obtained, when the control function is constrained and the performance index takes on the general form. Also it is concluded that the lumped parameter system is the special case of the distributed parameter system.

• Journal of Electrical Engineering and Technology
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• 제11권2호
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• pp.425-436
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• 2016

In this paper, a parameter optimization based iterative learning control strategy is presented for permanent magnet synchronous motor control. This paper analyzes the mechanism of iterative learning control suppressing PMSM torque ripple and discusses the impact of controller parameters on steady-state and dynamic performance of the system. Based on the analysis, an optimization problem is constructed, and the expression of the optimal controller parameter is obtained to adjust the controller parameter online. Experimental research is carried out on a 5.2kW PMSM. The results show that the parameter optimization based iterative learning control proposed in this paper achieves lower torque ripple during steady-state operation and short regulating time of dynamic response, thus satisfying the demands for both steady state and dynamic performance of the speed regulating system.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권10호
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• pp.464-472
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• 2001

This study uses distributed parameter systems as the spatial discretization technique, modelling in lumped parameter systems, and applies fast WALSH transform and the Picard's iteration method to high order partial differential equations and matrix partial differential equations. This thesis presents a new algorithm which usefully exercises the optimal control in the distributed parameter systems. In exercising optimal control of distributed parameter systems, excellent consequences are found without using the existing decentralized control or hierarchical control method. This study will help apply to linear time-varying systems and non-linear systems. Further research on algorithm will be required to solve the problems of convergence in case of numerous applicable intervals.

• Journal of Power Electronics
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• 제17권5호
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• pp.1211-1222
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• 2017

In order to decrease the parameter sensitivity of deadbeat direct torque control (DB-DTC), an improved deadbeat direct torque control method for surface mounted permanent-magnet synchronous motor (SPMSM) drives is proposed. First, the track errors of the stator flux and torque that are caused by model parameter mismatch are analyzed. Then a sliding mode observer is designed, which is able to predict the d-q axis currents of the next control period for one-step delay compensation, and to simultaneously estimate the model parameter disturbance. The estimated disturbance of this observer is used to estimate the stator resistance offline. Then the estimated resistance is required to update the designed sliding-mode observer, which can be used to estimate the inductance and permanent-magnetic flux linkage online. In addition, the flux and torque estimation of the next control period, which is unaffected by the model parameter disturbance, is achieved by using predictive d-q axis currents and estimated parameters. Hence, a low parameter sensitivity DB-DTC method is developed. Simulation and experimental results show the validity of the proposed direct control method.

• Journal of Power Electronics
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• 제6권3호
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• pp.235-244
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• 2006

Recently, speed sensorless vector control for synchronous reluctance motors (SYRMs) has deserved attention because of its advantages. Although rotor angle calculation using flux estimation is a straightforward approach, the DC offset can cause an increasing pure integrator error in this estimator. In addition, this method is affected by parameter fluctuation. In this paper, to control the motor at the low speed region, a modified programmable cascaded low pass filter (MPCPLF) with sensorless online parameter identification based on a block pulse function is proposed. The use of the MPCLPF is suggested because in programmable, cascade low pass filters (PCLPF), which previously have been applied to induction motors, the drift increases vastly wl)en motor speed decreases. Parameter identification is also used because it does not depend on estimation accuracy and can solve parameter fluctuation effects. Thus, sensorless speed control in the low speed region is possible. The experimental system includes a PC-based control with real time Linux and an ALTERA Complex Programmable Logic Device (CPLD), to acquire data from sensors and to send commands to the system. The experimental results show the proposed method performs well, speed and angle estimation are correct. Also, parameter identification and sensorless vector control are achieved at low speed, as well as, as at high speed.