• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.2
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• pp.134-141
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• 2004

This paper presents a method of synchronous rectifier(SR) for improving the efficiency in DC/DC converter. The proposed method is used push-pull topology on primary as a single winding self driven synchronous rectification(SWSDSR). Specially, this method can improve efficiency to turn on SR switch during dead time. Finally, the simulation and experimental results will be given to show comparison and analysis on the efficiency between self driven synchronous rectification(SDSR) and SWSDSR method.

• 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.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.192-198
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• 2001

In this study, a methodology of synchronous control which can be applied to position synchronization of a two-axes driving system has been developed. The synchronous error is caused by model uncertainties and torque disturbance of each axis. To overcome these problems, the proposed synchronous control system has been composed of two speed controllers and one synchronous controller. The speed controllers based on PID control law are aimed at the following to speed reference. And the parameters of speed controllers have been designed in order that speed response of the second axis corresponds with one of first axis. Especially, considering to model uncertainties of each axis, the synchronous controller has been designed using H$\infty$ control theory. The controller eliminates the synchronous error by controlling speed of the second axis. The effectiveness of the proposed method has been verified through simulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.461-463
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• 2018

In this paper, we have studied the devices needed for long distance wireless transmission of SDH network. This devices propose wireless transmission and measurement method of STM-1(basic transmission unit of SDH method) signal and 200Mbps synchronous ethernet. The synchronous clock recovery function is provided for STM-N transmission and synchronous ethernet transmission, and spare clock switching function is designed for stable synchronization. In addition, we discussed the measurement method of STM-N and synchronous Etherent communication method in wireless transmission section.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.166-170
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• 2003

This paper presents the TTFC(Two Transistor Forward Converter) using Synchronous Rectifier of Compulsory Control-driver. The two transistor forward circuit is used to decrease voltage stress of primary side and the synchronous rectifier is used to reduce current stress of secondary side. Previous synchronous rectifier's MOSFET of TTFC have long dead time This paper presents synchronous rectifier of compulsory control-driver for minimized dead time. This paper compared with diode rectifier, self-driven synchronous rectifier and compulsory control-driver synchronous rectifier of TTFC. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 200W 100kHz MOSFET based experimental circuit.

• 전기의세계
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• v.24 no.2
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• pp.78-83
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• 1975

There are many studies recently, on a wound rotor induction motor operation as synchronous rotating speed, and such an induction motor is so called an induction synchronous motor. In above desciption the region of pull into-step that the wound rotor induction motor as a synchronous motor has not been calculated. This paper deals with such a region. Generally, induction synchronous motor is different from a synchronous motor in many respects. In considering these respects, characteristic equations of motion for this motor are induced adoption small signal linearization, continuous quasili-nearization and state variable grouping technique. For pulling-into-step of Induction Synchronous Motor, we first analyze these equations with digital computer and compare the former with datas calculated by motor experimentation.

• 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.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.178-181
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• 2005

This paper presents a synchronous rectifier in a LLC half bridge topology. The proposed synchronous rectifier is used to a current driven synchronous rectifier(SR). If FET is driven without dead times. Voltage driven synchronous rectifier may introduce voltage and current surge during the zero dead times. To solve this problem, we propose to use modified current driven synchronous rectifier. Finally, the prototype is built and comparison on the current and voltage driven synchronous rectifier(SR).

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.248-252
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• 2002

In this study, a synchronous controller which can be applied to two-axes position synchronization has been developed. The synchronous control system based on coupling structure has been composed of speed and synchronous controller. The speed controller has been designed to fellow speed reference. And the synchronous controller has been designed in the view point of accurate synchronization and robust stability by $H_{\infty}$ approach. The effectiveness of the designed synchronous controller has been demonstrated by experiment.