• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.597-605
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• 2010

This paper presents a contribution to parameter identification of a non-linear system using a new strategy to improve the genetic algorithm (GA) method. Since cost function plays an important role in GA-based parameter identification, we propose to improve the simple version of GA, where weights of the cost function are not taken as constant values, but varying along the procedure of parameter identification. This modified version of GA is applied to the induction motor (IM) as an example of nonlinear system. The GA cost function is the weighted sum of stator current and rotor speed errors between the plant and the model of induction motor. Simulation results show that the identification method based on improved GA is feasible and gives high precision.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1810-1812
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• 2002

This test was performed to assess the insulation deterioration condition of the stator winding of Chung-Ju hydrogenerator #4 and Dae-Cheong hydrogenerator #2 which had been in service after being constructed 1980. The insulation diagnostic tests 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 factory test measurements.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2006.06a
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• pp.77-80
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• 2006

This paper based on spiral vector, three phase induction motor is described a detailed modeling by a phase segment methode. Based on this model, A torque control and the equation of regenerative power for the induction motor drive, based on the field acceleration method(FAM), is presented. The speed control system is designed to be applied voltage source inverters that is easy the current type feedback of power regeneration for motor drive. The ability of shaving power to be measured power regeneration has been investigated in speed acceleration and reduction. And it is change of stator resistance that the voltage commands include error, the ripple of exited voltage and torque occur from the results. The experimental tests verify the performance of the proposed regenerative drive for FAM, proving that good behavior of the drive is achieved in the transient and steady-state operating conditions.

• Progress in Superconductivity and Cryogenics
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• v.15 no.1
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• pp.35-39
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• 2013

The superconducting Homopolar motor is manufactured and tested. Homopolar motor system is simple and solid as the field coil of the motor is fixed near the stator coil without rotating system. In this paper, a 5 kW fully superconducting homopolar motor which has high temperature superconducting armature and field coils is manufactured and tested in liquid nitrogen. The critical current test results of the used 2G superconducting wire, pancake coil for rotor winding and race-track coils for armature winding are reported. Also, the test result of rotating and operating performance is presented. The operating frequency is to be 5 Hz for low-speed rotating. The developed fully superconducting Homopolar motor is the world's first.

• 전기의세계
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• v.21 no.1
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• pp.7-12
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• 1972

General steady state equivalent circuits are derived for the family of single phase motor having two windings with non-quadrature. First, the fundamental voltage equations of motor are derived by Faraday-Krichhoff's low in the fiew of the flux distribution in the modified motor with Kron primitive machine. Those equations are arranged in to f-b equations by transformation matrix. To using the above equations for circuit; 1) The concept of current-source was much help to sove the realtions between matrix impedance equation and circuit analysis 2) The simplification of the circuit to the mutual impedance matrix elements is easy to considerations of motor characteristics in the case of inserted external auxiliary winding impedance. Finally, this equivalent circuit showing as a single phase induction motor with quadrature winding is described by each conditions.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.8
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• pp.363-368
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• 2006

This paper presents a new method on reducing commutation torque ripples generated in brushless dc motor drives. In such drives the current ripples are generated by motor inductance in stator windings and the back EMF. The ripples suppression techniques that are practically effective in high speed as well as in low speed regions are rarely found. The proposed method here is based on a strategy that the commutation intervals of the incoming ang the outgoing phases can be equalized by a proper PWM control. The controller is implemented by a 16-bit microprocessor and effectiveness of the proposed control method is verified through experiments.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.482-489
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• 2006

This paper presents the generalized dynamic modeling of self-excited induction generator (SEIG) using state-space approach. The proposed dynamic model consists of induction generator; self-excitation capacitance and load model are expressed in stationary d-q reference frame with the actual saturation curve of the machine. An artificial neural network model is implemented to estimate the machine magnetizing inductance based on the knowledge of magnetizing current. The dynamic performance of SEIG is investigated under no load, with the load, perturbation of load, short circuit at stator terminals, and variation of prime mover speed, variation of capacitance value by considering the effect of main and cross-flux saturation. During voltage buildup the variation in magnetizing inductance is taken into consideration. The performance of SEIG system under various conditions as mentioned above is simulated using MATLAB/SIMULINK and the simulation results demonstrates the feasibility of the proposed system.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.10
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• pp.522-527
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• 2003

This paper proposes a new speed and flux estimation method which has the robustness against the variation of the electrical parameters of the motor and the superiority in the dynamic characteristics. In the proposed method, the stator currents and the rotor fluxes are observed on the stationary reference frame using the sliding mode concept. And the rotor speed is estimated using the current estimation errors and the observed rotor fluxes based on the Lyapunov stability theory. Also a design method of the observer gain is proposed to minimize the effect of the speed estimation error on the rotor flux observation. The experimental results are shown to verify that the proposed method shows the excellent performances under the variations of motor resistance and inductance.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2136-2138
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• 1998

In this study, the speed sensorless vector control system with the magnetizing inductance compensation structure is presented. The estimations of the rotor speed and the magnetizing inductance using the terminal voltages and currents are performed with the reduced order Gopinath flux observer. The rotor speed is estimated by the torque producing current which is derived from the estimated value of the rotor flux and the measured stator currents. In order to compensate the variation of the magnetizing inductance under the saturated conditions, we also established the compensation scheme which is made with the instantaneous reactive power. The validity of the proposed method is verified by simulation results.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.865-866
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• 2006

Bearingless Switched Reluctance Motor(SRM) have combined characteristics of SRM and magnetic bearing. Production of radial force for rotor shaft magnetic suspension is explained with differential stator windings. Bearingless SRM is simple structurally because the permanent magnet does not exist and bearing does not take the influence at the environment because it does not exist and has strong torque, and loss of bearing by bearing current has the advantage not to exist. In this paper, a design method of bearingless SRM for suspension power and starting torque is proposed. The design model is implement by maxwell.