• Journal of international Conference on Electrical Machines and Systems
• /
• v.3 no.2
• /
• pp.215-221
• /
• 2014

To satisfy the high voltage direct current (HVDC) grid connection demand for wind power generation system, a novel topology and control strategy of HVDC grid connection for open-winding permanent magnet synchronous generator (PMSG) based wind power generation system is proposed, in which two generator-side converter and two isolated DC/DC converters are used to transmit the wind energy captured by open winding PMSG to HVDC grid. By deducing the mathematic model of open winding PMSG, the vector control technique, position sensorless operation, and space vector modulation strategy is applied to implement the stable generation operation of PMSG. Finally, the simulation model based on MATLAB is built to validate the availability of the proposed control strategy.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.51 no.6
• /
• pp.307-312
• /
• 2002

Inter-turn short circuits can have significant effects on a generator and its performance. The Inter-turn short circuits sensor for synchronous generator's field winding has been developed. The sensor, installed in the generator air-gap, senses the slot leakage flux of field winding and produces a voltage waveform proportional to the rate of change of the flux. For identification of reliability for sensor, a shorted- turn test was performed at the Seoinchon combined cycle power plant on gas turbine generator and stim turbine generator. This sensor will be used as a detecting of Inter-turn short circuits for synchronous generator's field winding.

• Proceedings of the KIEE Conference
• /
• 1996.07a
• /
• pp.89-91
• /
• 1996

In dry-winding(unfilled) superconducting magnets, the behavior of liquid helium occupying the extremely small void space within the winding is contributed as a primary factor for transient stability of magnets. Therefore, numerical experiments have been carried out concerning the influences of transient heat transfer of liquid helium ocupying the void space in the winding and thermal properties of insulation at the conductor surface on the transient stability of magnets, by using three-dimensional finite element method(FEM). In this paper, we are going to consider three different cases for heat transfer characteristics of liquid helium to observe the influences of the rest of liquid helium in void space within the winding on the transient stability.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2001.05a
• /
• pp.193-196
• /
• 2001

The purpose of this study is the design of composite shaft which is wound by Filament Winding method. Classical laminated plate theory was used for analyzing the stress, and for structure design. The diameter and thickness of composite shaft were calculated by this theory. The result that if tensile stress was zero, torsion stress was a certain value below 0.4(diameter rate) and torsion strength was the highest value on $45^{\circ}C$(winding angle). In case of $90^{\circ}C$(winding angle), we have to consider the torsional monent when the composites shaft was load.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.10
• /
• pp.809-813
• /
• 2010

Frequency domain measurement of propagation loss for ultra high frequency (UHF) partial discharge in the winding of power transformer using a spectrum analyzer and pulse generator is presented. We compared the performance of the method using a network analyzer with and without a winding. Using a network analyzer simplifies the measurement and offers better dynamic range and frequency range. It also provides precise propagation loss within the winding in frequency domain at UHF range. We applied this method to measure UHF propagation loss of transformer mock-up, modeled 154 kV 20 MVA power in KEPCO substation.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.5
• /
• pp.730-735
• /
• 2012

This paper presents a method to design the waveform of a back electromotive force (back EMF) of an axial flux permanent magnet (AFPM) motor using printed circuit board (PCB) windings. When the magnetization distribution of permanent magnet (PM) is given, the magnetic field in the air gap region is calculated by the quasi three dimensional (3D) space harmonic analysis (SHA) method. Once the flux density distribution in the winding region is determined, the required shape of the back EMF can be obtained by adjusting the winding distribution. This can be done by modifying the distance between patterns of PCB to control the harmonics in the winding distribution. The proposed method is verified by finite element analysis (FEA) results and it shows the usefulness of the method in eliminating a specific harmonic component in the back EMF waveform of a motor.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1995.10a
• /
• pp.1165-1168
• /
• 1995

This paper describes the evaluation of a robot based filament winding cell consisting of an industrial robot (ASEA IRB 6/2) and an in-house fabricated mandrel drive mechanism, both being coordinated by a personal computer. As in many manufacturing processes, tradeoffs exist between accuracy and speed. The accuracy versus speed relationships of the robotic winding cell were experimentally determined for discrete, fine and medium movement modes while traversing a segmented delivery eye path for a cylindrical mandrel in three configurations (in-line, offset and angled with respect to the axis of rotation). the results show that the robot winding cell is appropriate for very accurate winding of fibre strands if the mandrel axis is concentric with the mandrel drive axis and the discrete mode(i.e. low speed) of the robot is used.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.5
• /
• pp.99-107
• /
• 2003

In a winding process, important control specifications include regulation of web tension and velocity. In this research, an adaptive controller has been developed for controlling web tension and velocity in winding processes. For the controller design, the linear quadratic regulator theory has been adopted and a gain-scheduling scheme has been incorporated. A prototype winding system has been constructed, and the controller has been implemented in a real-time PC-based environment. The performance of the closed loop system has been evaluated via simulation and experiments, and it was observed that both the web tension and velocity could be regulated within a small tolerance.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.4
• /
• pp.643-649
• /
• 2012

The diagnosis technique of stator winding faults based on Motor Current Signature Analysis(MCSA) was suggested. Park's vector pattern, the circle that is drawn by d-q transformed currents($i_d$, $i_q$), is widely used for stator winding faults detection. The current Distortion Ratio(DR), defined by the ratio of max axis and min axis of ellipse of Park's vector's pattern, was more simple and powerful method than the Park's vector pattern. In this study, a calculation method of distortion ratio of Park's vector pattern was suggested for auto diagnosis of stator winding short fault and usefulness of suggested calculation method of distortion ratio was verified through simulation using LabVIEW program.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.8
• /
• pp.1108-1114
• /
• 2013

This paper presents a new winding topology for MW class offshore wind generator having modular and dual 3-phase. Based on proposed simplified relationship between magnetic flux and phase current in the air gap, several new windings for modular and dual 3-phase are made. In case of one inverter operation or faulty operation, the proposed model can have balanced 3-phase induced voltage whereas the conventional generator with modular winding has unbalanced induced voltage, which can be important issue in offshore generator. The model was applied into 6MW prototype machine with dual 3-phase. Using finite element analysis, induced voltage, inductance were investigated. The results show that the proposed modular winding can be applicable to dual inverter system with electrically balanced voltage.