• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.252-255
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• 2001

In this paper, a mathematical model of permanent magnet synchronous motor (PMSM) fed by inverter with Direct Torque Control (DTC) Dynamic and steady state characteristics of PMSM is simulated and analyzed: electro-magnetic torque response, speed response, locus of the stator flux linkage. It is mathematically proven that the increase of electromagnetic torque in a permanent magnet motor is proportional the increase of the angle between the stator and rotor flux linkages, and, therefore, the fast torque response can be obtained by adjusting the rotating speed of the stator flux linkage as fast as possible. The simulation results verify the proposed control and also show that the torque response under DTC is much faster than the PWM current controlled drive.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.39-41
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• 2004

The measurements were performed to assess the insulation deterioration condition of the stator winding of Dae-Cheong hydro-generator #2 which had been in service after being constructed 1980. After repair of the stator winding insulation, we conducted insulation diagnostic tests which include resistance, polarization index(P.I), AC current, dissipation factor($Tan\delta$) and partial discharges ($Q_{max}$). The results of diagnostic tests were compared to the previous records. On the basis of these test results, this paper tried to present the importance of insulation repair for the generator stator winding.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.397-400
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• 2001

This paper presents a implementation of digital sensorless position control system of surface permanent-magnet synchronous motor (SPMSM) drive with a direct torque control (DTC). The system are stator flux and torque observer of stator flux feedback control model that inputs are current and voltage sensing of motor terminal with estimated rotor angle for a low speed operating area, two hysteresis band controllers, an optimal switching look-up table, rotor speed estimator, and IGBT voltage source inverter by using fully integrated control software. The developed sensorless control system are shown a good motion control response characteristic results and high performance features using 1.0 (kW) purposed servo drive SPMSM.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.23-24
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• 2007

Most of modern wind turbines employs a doubly-fed induction generator (DFIG) system because it has many advantages due to variable-speed operation, relatively high efficiency and it small converter size. The DFIG system uses a wound rotor induction machine so that the magnetizing current of the generator can be fed from both the stator and the rotor. This paper presents a protection relaying algorism for DFIG using the DQ equivalent circuits. The induced voltages calculated from the stator and rotor sides are nearly the same in the steady state. They become different in the DQ equivalent circuits during an internal fault. The proposed algorithm compares the inducted voltages estimated from the stator and the rotor circuit converted into the stationary reference frame. If the difference between the induced voltages exceeds the threshold, the proposed algorithm detects an turn-to-turn fault.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.74-76
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• 2005

The SRG(Switched Reluctance Generator) consists of simple stator and rotor. The advantage of SRG is very endurance and low cost. Because of SRG have no magnetic, So we should obtain current of magnetic to stator. But in this step SRG have disadvantage. Disadvantage of SRG is more torque ripple, vibration and noise than other machines. This paper shows the simulation of SRG with 3phases, 6 stator poles and 4 rotor poles. We intpret the characteristics of SRG's constant voltage and torque ripple according to change switching angle.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1137-1140
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• 2014

Faulty electric motors onboard vessels with anomalies in windings or poor insulation are usually repaired at land based workshops and reinstalled in place by crew hands after receiving the repaired motors. Especially for 3 phase induction motors which need Y-${\delta}$ starters with 6 lead wires, it would happen that the polarities of stator windings cannot be well distinguished if the original tags of these wires are erased or not visible clearly, resulting in subsequent damage to the repaired motor due to extreme current flow when the power is given to the motor the stator windings of which are wrongly connected in the polarity. This study proposes an easy way to make correct connection in winding polarities without failures based on the electro-magnetically induced voltages on windings when a slight DC current is supplied to a winding coil by using an analog multi-tester. The proposed method is applied to actual motors and delves into the applicability for polarity discrimination through a few measurements onboard vessels.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.180-184
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• 2007

For driving a sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, a $120^0$ delayed three phase sinusoidal current input which matched with the absolute rotor position is needed at a stator coil. So, the detection of absolute rotor position is required inevitably. Thus the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. This study purposes to design signal processing logic circuits which can detect the absolute position of motor with a modem encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1018-1024
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• 2011

For the driving of the sinusoidal type permanent magnet synchronous motor with a maximum continuous torque, the 1200 delayed three phase sinusoidal current inputs which matched with the absolute rotor position are needed at the stator coil. Therefore, the detection of a absolute rotor position is required inevitably. And the right angle relationship between stator magnetic field and rotor magnetic field has to be preserved at a stator by this commutation action. The detection of a absolute position for the commutation can be made generally by the output signal analysis of the encoder attached at a motor shaft. The purposes of this study are to design signal processing logic circuits which could detect the absolute position of motor with a modern encoder system and generate the three reference wave for making sinusoidal current input at a stator coil.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.1
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• pp.81-90
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• 2002

This paper presents an Implementation of digital high-performance position sensorless control system of Reluctance Synchronous Motor(RSM) drives with Direct Torque Control(DTC). The system consists of stator flux observer, speed and torque estimator, two digital hysteresis controllers, an optimal switching look-up table, Insulated Gate Bipolar Transistor(IGBT) voltage source inverter, and TMS320C31 DSP board. The stator flux observer Is based on the combined voltage and current model with stator flux feedback adaptive control of which inputs are current and voltage sensed on motor terminal for wide speed range. In order to prove the suggested sensorless control algorithm for industrial field application, we have some simulation and actual experiment at low and high speed range. The developed high-performance speed control by fully digital system are shown a good response characteristic of control results and high performance features using 1.0[kW] RSM having 2.57 reluctance ratio of $L_d/L_q$.

• Journal of Power Electronics
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• v.13 no.3
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• pp.369-380
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• 2013

Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.