• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.288-294
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• 2013

This paper introduces a novel method of on-line identifying the stator resistance and leakage inductance of dual three phase induction motor (DTPIM). According to the machine mathematical model, the stator resistance and leakage inductance can be estimated using the voltage and current values in harmonic subspace. Thus a method of voltage vector injection in harmonic subspace (VVIHS) is proposed, which causes currents in harmonic space. Then the errors between command and actual harmonic currents are utilized to regulate the machine parameters, including stator resistance and leakage inductance. The principle is presented and analyzed in detail. Experimental results prove the feasibility and validity of proposed method.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2072-2074
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• 2005

This test was performed to assess the insulation condition of the stator winding of 3.45kV hydro generator in insulation deterioration condition which was due to long service period(30years) since installed We extracted 12 stator wingdings from the hydro generator core, cut the stator windings into three parts(Middle winding part, slot winding part, end wingding part), and evaluated the insulation condition to know the deterioration condition of each parts. This insulation diagnostic tests include AC current, dissipation factor, and partial discharg test.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.222-223
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• 2007

In 6.6kV Rotary Machine Stator Windings, Corona Discharge, Discharge at Conductor Surface, Slot Discharge and Endwinding Discharge is happended by electronic degradation. Also, if Partial Discharge cause in inner-part of Rotary Machine Stator Windings, it will be happended voltage and current pulse. In case of discharge spark, RF electromagnetic wave, which tranmits at discharge position, can happen. To detect this kind of RF electromagnetic wave efficiently, we have designed Planar Antenna Sensor with the CST MWS simulation program. Also we have confined the application possibility, which can analize the partial discharge in Rotary Machine Stator Windings. In the Future, sample of planar antenna sensor will be able to compare with the data of simulation by CST MWS program.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.5
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• pp.427-436
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• 2002

This paper presents an implementation of high-dynamic performance of position sensorless motion control system of Reluctance Synchronous Motor(RSM) drives for an industrial servo system with direct torque control(DTC). The problems of high-dynamic performance and maximum efficiency RSM drives controlled by DTC are saturation of stator linkage flux and nonlinear inductance characteristics with various load currents. The accurate estimation of the stator flux and torque are obtained using stator flux observer of which a saturated inductance $L_d$ and $L_q$ can be compensated by adapting from measurable the modulus of the stator current and rotor position. To obtain fast torque response and maximum torque/current with varying load current, the reference command flux is ensured by imposing $I_{ds} = I_{qs}$. This control strategy is proposed to achieve fast response and optimal efficiency for RSM drive. In order to prove rightness of the suggested control algorithm, the actual experiment carried out at $\pm$20 and $\pm$1500 rpm. The developed digitally high-performance motion control system shown good response characteristic of control results and high performance features using 1.0kW RSM which has 2.57 Ld/Lq salient ratio.

• Journal of Power Electronics
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• v.16 no.2
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• pp.542-552
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• 2016

Central 60° synchronous modulation is an easy pulse-width modulation (PWM) method to implement for the traction inverters of urban rail trains at a very low switching frequency. Unfortunately, its switching patterns are determined by a Fourier analysis of assumed steady-state voltages. As a result, its transient responses are not very good with over-currents and high instantaneous torque pulses. In the proposed solution, the switching patterns of the conventional central 60° modulation are modified according to the dynamic error between the target and actual stator flux. Then, the specific trajectory of the stator flux and current vector can be guaranteed, which leads to better system transients. In addition, stator flux control is introduced to get smooth mode switching between the central 60° modulation and the other PWMs in this paper. A detailed flow chart of the control signal transmission is given. The target flux is obtained by an integral of the target voltage. The actual PMSM flux is estimated by a minimum order flux state observer based on the extended flux model. Based on a two-level inverter model, improved rules in the α-β stationary coordinate system and equations of the switching patterns amendment are proposed. The proposed method is verified by simulation and experimental results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.11
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• pp.1067-1071
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• 2006

Prior to destructive testing, diagnostic tests were performed in ten high voltage motors. Diagnostic tests included polarization infer, ac current, dissipation factor$(tan{\delta})$ and partial discharge magnitude. The rewind of motet slater insulation at rated voltage is assessed by the results of these tests. After completing the diagnostic tests, the stator windings of motors were subjected to gradually increasing ac voltage, until the insulation punctured. No. 8 motor failed near rated voltage of 19.0 kV. The breakdown voltage of No. 4 motet was 7.0 kV which is lower that expected for good quality coils in 6.6 kV class motors. The failure was located in a line-end coil at the exit from the core slot. These two motors began operation in 1994. While testing No. 7 motor, flashover occurred between the stator winding and the stator frame at 15 kV. The relationship between the diagnostic test and the drop in insulation breakdown voltage was analyzed.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2002-2004
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• 1998

In this paper, the compensation algorithm of the stator resistance which is essential to improving the performance of the direct vector control system is proposed. This paper focuses on the improvement in the torque response of the direct vector control in a constant speed region. The conventional compensation algorithms are analyzed and a new method is developed to compensate the stator resistance in the direct vector control system. In addition, the effect of the variation of the stator resistance on the drive performance is analyzed for the vector control. The proposed algorithm is very simple to implement that does not require the modifications on the motor model or additional interrupts of the controller. Also, the value of the stator resistance can be obtained in real-time through the measurement of the terminal voltage and current. From the simulation and experimental results, the validity of the proposed scheme is confirmed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.3
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• pp.524-530
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• 2011

This paper analyzes fault tolerance under a stator turn fault, according to the winding configuration. Improvement of torque characteristics and fault tolerance can be achieved by winding configuration without additional methods. And, torque characteristics and fault tolerance according to the winding configuration can be usually analyzed by analytical method. But, when the stator turn fault generates, compare to the steady-state, analysis of torque characteristics and fault tolerance using the analytical method is not accurate because it does not reflect influence in mutual inductance and magnetic non-linearity. Therefore, analysis of torque characteristics and fault tolerance has to be performed by using the numerical method under fault condition. This paper develops fault characteristics according to the winding configuration using the FEM-base model considered magnetic non-linearity. And, this paper suggests fault tolerance improvement according to the winding configuration, by the comparison of 8/12 and 10/12 models, under fault condition.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.906-908
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• 2002

The technical improvement of servo system, it is required to study on robust control method in company. It needs to study on brake system that has constant torque-speed performance as load variation. In this paper, braking torque characteristics of eddy current braker between electromagnet stator and rotating disk are analyzed. The torque-speed characteristics and proper disk construction are presented. From the computer simulation results, it was found that eddy current braking torque is linear or approximately constant over the desired speed range depending on the rotor material, disk construction, pole number and pole displacement of stator. The relationship of these parameters are confirmed by experimental result.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.583-586
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• 1991

This paper presents a comprehensive study on the stability of several control schemes for the induction motor driven by current source inverters. A stator voltage-controlled current source inverter drive system without a speed sensor is investigated in order to find appropriate control schemes, which are primarily based on direct or, alternatively, indirect frequency control scheme. The overall control systems with either voltage control loop or current and voltage control loops provided in addition to each frequency control scheme are analyzed by utilizing the root locus method and simulated by computer to illustrate the validity of this analysis.