• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.107.4-107
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• 2001

In this paper, the guaranteed stability margins of LQ optimal regulators for a performance index with cross-product terms are suggested in the discrete-time case. An example for the LQ optimal regulator of an inverted pendulum system is given to demonstrate the validity of the suggested stability margins.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.78-85
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• 2011

In order to design the control system of the magnetic bearing for the high speed 3 phase induction motor, the mathematical modeling was conducted and LQ regulator system was designed. When the plant is controllable and detectable, the nominal stability of LQ regulator could be guaranteed. However, LQ regulator doesn't ensure the robustness of stability and performance for the real system because LQ control is the mathematical optimal theory. In this paper to ensure the robustness of stability and performance for the real system, the control systems are designed by the simulation to the variation system parameters and this method was confirmed as an effective means.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.367-369
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• 1986

Guaranteed cost control is a method applicable to a class of systems with uncertain parameters that guarantees an upper bound of the cost functional. This paper is concerned with a matrix decomposition technique used to yield a reasonable upper bound of the cost functional for a finite-time LQ regulator problem. The uncertain linear systems dealt with in this paper are described by a set of state equations of single-input phase-variable canonical form which contain unknown but bounded uncertain parameters.

• Journal of Institute of Control, Robotics and Systems
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• v.1 no.2
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• pp.83-87
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• 1995

본 논문에서는 이산시간 LQ 조절기의 안정도 강인성을 주파수 영역및 시간영역에서 고찰하고 그 향상책을 제시하낟. 주파수영역에서 강인성 척도인 궤환차행렬(return difference matrix) 의 최소특이치가 상태가중치 행렬과 제어가중치 행렬의 비와 반비례함을 보이고, 시간영역에서 매개변수의 변화에 대한 안정도 강인성 범위들을 얻는다. 이 범위들의 점근적 성질을 밝히기 위하여 LQ 궤환이득의 특이치들이 상태가중치 행렬과 제어기중치 행렬의 비의 증가함수 임을 보인다. 몇가지 조건하에서 시스템 행렬(입력행렬)에 대한 안정도 강인성 범위가 상태 가중치 행렬과 제어가중치 행렬의 비가 증가(감소)함에 따라서 증가함을 보이고, 이러한 사실들을 예제를 통하여 검증한다.

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.401-404
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• 1989

In this paper an optimal LQ controller is designed for the output characteristic improvement of buck-type switching regulators. State-space averaging method is adopted for modelling of switching regulators. The LQ controller is derived via an unified operator form for the application to both continuous-time and discrete-time control systems. Some design parameters of the LQ controller are chosen through a computer simulation and the LQ controller is implemented by analog circuits.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.33 no.2
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• pp.141-148
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• 1997

This paper is concerned with the vibration control of multi-layer structure for ultra-tall buildings and main tower of large bridge etc. We have modeled the multi-layer structure with the distributed mass system as the lumped mass system of two-degree-of-freedom structure and made experimental equipment. The LQ optimal control theory is applied to the design of the control system. The designed control system is simulated by computer. As a result, the LQ regulator showed good vibration control performance with impact excitation.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.125-129
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• 1987

The stability margin of the LQ regulator is investigated in the time domain. it is shown that the same guaranteed gain margin as that of the frequency domain analysis can be obtained with simple assumptions for the continuous time systems. It is also shown that the allowable modelling error bound can be expressed in terms of system matrices and Riccati equation solution. Guaranteed qain. margin and the allowable modelling error bound for the discrete time systems are also obtained by the similar procedures. In this case, through the some examples, the gain margin is shown to be less conservative than the frequency domain analysis result.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1470-1473
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• 2003

In this paper the networked control systems (NCS) problem is discussed where plants and controllers are distributed and interconnected by a common network. NCS is designed with LQ regulator and applied to an inverted pendulum accounting for the multiple time delays. We are to deals with a networked control system with a single controller, multiple sensors and multiple actuators. Since these parts are distributed, they are interconnected by communication networks. An NCS with LQ regulator is designed and applied to an inverted pendulum as a benchmark plant to check its performance under time delays induced by the network. Network induced delays are composed of two parts. One is the delay from controller to plant, and another is from plant to controller. They are assumed to be constant in this paper, and the plant and controller are discretized. To apply the LQ regulator the NCS model is transformed to a standard model with delayed states as state variable. And real network induced delay is measuring in TCP/IP network assuming that two delays are constant.

• Journal of Wind Energy
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• v.2 no.1
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• pp.74-81
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• 2011

This paper deals with the application of LQ control to the power curve tracking control of wind turbine. However, two more additional tasks are required to apply the LQR theory to wind turbine control. One is the tracking problem instead of regulation, because the wind turbine is controlled as variable speed and variable pitch. The other is LQ integral control., because the rotor speed should be tightly controlled without any steady state error. Starting from the analysis of wind characteristics, design requirement of a wind turbine control system is defined. A design procedure of LQ tracking with integral control is introduced. The performance of LQ tracking system is analyzed and evaluated by numeric simulation.

• Journal of Power Electronics
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• v.1 no.2
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• pp.117-126
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• 2001

A synchronous motor(SM) with q-axis special field winding of which the q-axis field-current compensates and cancels armature reaction can be driven at unity power factor under the conditions of transient state as well as steady state. The motor operates in high efficiency in all conditions. However, in order to obtain maximum performance of the motor, it is required that the time constant of armature circuit corresponds to that of q-axis field circuit. Inverse LQ(ILQ) design method on a basis of the pole assignment is suitable for this problem:(1) The time constants of the output responses can be designed for desired specifications, (2) Relations between feedback gains and response of closed loop system are very clear and (3) Optimal solutions can be given by simple procedure of ILQ method without solving the Ricaati's equation, compared to the usual LQ design method. Accordingly, the ILQ method can make the responses of armature current and q-axis field-current correspond. In this paper, it is proved by numerical simulations and experiments that the ILQ method is very effective for optimal regulator design of this plant and realizes a high-performance motor with unity power factor and high efficiency.