• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.998-998
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• 2008

It is difficult to find for analysis solution of the synchronous generator exciter system. Recently, it had good performance UPS converter system using CRA method. The single converter of synchronous generator excitor system under considerations : (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load condition, and (ii) the digital controller shall be employed at a fixed sampling. It is shown that the synchronous exciter system can be achieved by the proposed controller using Characteristic Ratio Assignment.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.449-450
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• 2008

It is difficult to find for analysis solution of the synchronous generator exciter system. Recently, it had good performence UPS converter system using CRA method. The single converter of synchronous generator excitor system under considerations : (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load condition, and (ii) the digital controller shall be employed at a fixed sampling. It is shown that the synchronous exciter system can be achieved by the proposed controller using Characteristic Ratio Assignment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1245-1254
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• 2004

In this paper, we deal with a precise position synchronous control of four-axes system which is working under various load disturbances. Each axis driving system is consisted of a speed controller and an acceleration controller as an inner loop instead of conventional current control scheme. The acceleration control plays an important roll to suppress load disturbances quickly. Also, each axis is coupled by a maximum position synchronous error comparison to minimize position synchronous errors according to integration of speed differency. As a result, the proposed system enables precise synchronous control with good robustness against load disturbances during transient as well as steady state. The stability and robustness of the proposed system are investigated through its frequency characteristic and numerical simulations. Finally, experimental results under load disturbances demonstrate the effectiveness of the proposed control system fur four-axes position synchronous control.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.2
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• pp.242-249
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• 2001

In this study, a methodology of synchronous control has been developed that can is applied to position synchronization of a two-axes driving system such as overhead crane. The synchronous error is caused by model uncertainties and torque load at each axis. To overcome these problems, the synchronous control system has been composed of two disturbance observers to calculate the torque disturbance and one synchronous controller to eliminate synchronous error. By considering model uncertainties of each axis, the synchronous controller has been designed using H(sub)$\infty$ control theory. The effectiveness of the proposed method has been verified through simulation.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.2078-2090
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• 2001

This paper deals with a precise position synchronous control by a cooperative control method of two axes rotating systems. First, the system's dynamics including motor drives described by a motor circuit equation and Newton's kinetic formulation about rotating system. Next, based on conventional PID(Proportional, Integral, Derivative) control law, current and speed controller are designed very simply to follow up reference speed correctly under some disturbances. Also, position synchronous controller designed to minimize position errors according to integration of speed errors between two motors. Then, the proposed control enables the distributed drives by a software control algorithm to behave in a way as if they are mechanically hard coupled in axes. Further, the stabilities and robustness or the proposed system are investigated. Finally, the proposed system presented here is shown to be more precise position synchronous motion than conventional systems through some simulations and experiments.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.405-415
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• 2016

This paper presents a model predictive control for shunt active power filters in synchronous reference frame using space vector pulse-width modulation (SVPWM). The three phase load currents are transformed into synchronous rotating reference frame in order to reduce the order of the control system. The proposed current controller calculates reference current command for harmonic current components in synchronous frame. The fundamental load current components are transformed into dc components revealing only the harmonics. The predictive current controller will add robustness and fast compensation to generate commands to the SVPWM which minimizes switching frequency while maintaining fast harmonic compensation. By using the model predictive control, the optimal switching state to be applied to the next sampling time is selected. The filter current contains only the harmonic components, which are the reference compensating currents. In this method the supply current will be equal to the fundamental component of load current and a part of the current at fundamental frequency for losses of the inverter. Mathematical analysis and the feasibility of the suggested approach are verified through simulation results under steady state and transient conditions for non-linear load. The effectiveness of the proposed controller is confirmed through experimental validation.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.189-195
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• 2005

This paper presents a new velocity estimation strategy for a non-salient permanent magnet synchronous motor drive without high frequency signal injection or special PWM pattern. This approach is based on the d-axis current regulator output voltage of the drive system, which contains the rotor position error information. The rotor velocity can be estimated through a rotor position tracking PI controller that controls the position error at zero. For zero and low speed operation, the PI gain of the rotor position tracking controller has a variable structure according to the estimated rotor velocity. Then, at zero speed, the rotor position and velocity have sluggish dynamics because the varying gains are very low in this region. In order to boost the bandwidth of the PI controller during zero speed, the loop recovery technique is applied to the control system. The PI tuning formulas are also derived by analyzing this control system by frequency domain specifications such as phase margin and bandwidth assignment.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.79-86
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• 2012

This paper proposes PID and RIC (Robust Internal-loop Compensator) based motion controller using dual learning algorithm for position control of linear synchronous motor respectively. Its gains are auto-tuned by using two learning algorithms, reinforcement learning and neural network. The feedback controller gains are tuned by reinforcement learning, and then the feedforward controller gains are tuned by neural network. Experiments prove the validity of dual learning algorithm. The RIC controller has better performance than does the PID-feedforward controller in reducing tracking error and disturbance rejection. Neural network shows its ability to decrease tracking error and to reject disturbance in the stop range of the target position and home.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1791-1797
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• 2018

Sub-Synchronous Resonance (SSR) is a phenomenon that harms turbine generator shafts because the phenomenon induces sub-synchronous wavering in the system. In the study presented in this paper, a dynamic resistance bank is used to mitigate the occurrence of sub-synchronous phenomenon. A fuzzy logic controller using rotor speed deviation and its derivative as inputs is implemented to damp sub-synchronous oscillations more efficiently. An eigenvalue technique is used to analyse the stability of the system, and a simulation in MATLAB is conducted, based on the IEEE Second Benchmark, to validate the effectiveness of the proposed method under a 3-phase fault condition at an infinite bus. The time-domain simulation and eigenvalues are used to observe the proposed method's superior ability to damp sub-synchronous oscillation.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.3
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• pp.66-73
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• 2003

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axis rotating system is developed. Based on coupling structure, the synchronous control system is composed of disturbance observer, speed and synchronous controllers. The speed controller is designed to follows speed reference. The disturbance observer is designed to restrain synchronous error. In addition, the synchronous controller is designed for a viewpoint of accurate synchronization in lead compensation law. The effectiveness of the proposed method is verified through simulation.