• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.888-894
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• 1986

In this paper, a phase locked loop control system is designed to have high performance and stability in a 2-phase bifilar winding PM step motor. The BODE diagram analysis method is used to improve the stability and dynamic characteristic of the closed loop control system. Also, a PLL servo is used to accomplish high-precision speed and to attain smooth ness. In applying the PLL control to the step motor, a new design method is suggested to solve the control problem which occurs as a result of the limited maximum acceleration of the step motor. A simple design method is suggested without using the complicated multi-step characteirstic of the step motor in constant voltage driving. Computer simulation results agree clorelg with experiments, indicating that the PLL servo system of the step motor designed is very useful.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_2
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• pp.1003-1008
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• 2022

This paper proposes a method related to fault tolerance operation and characteristic analysis of asymmetric 6-phase permanent magnet synchronous motor. In general, motor drive systems with multi-phase structures can be continuously operated despite a reduction of power and speed by using a phase changeover or control techniques according to the failures. As a result, it is widely used in industrial fields such as aviation and defense, which require high efficiency and high reliability. In this paper, the second order ripple of the electrical fundamental freuqnecy occurs in the dq-axis currents of the synchronous coordinate system through mathematical analysis according to the switch open of the dual 3-phase inverter. Therefore, the fault tolerant operation method is presented by applying the fault detection method with a constant cycle for continuous operations. The effectiveness of the proposed fault tolerance operation method is verified through the several experiments.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1084-1086
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• 2003

3-Phase BLDC Motor, which is generally used, has limited usage in high speed, due to pulsation torque occurring commutation and variable speed. To solve this problem, it is necessary to increase invariable, pole number, or the number of slots. Currently, due to rapid growth of semiconductor technology and trend toward smaller and cheaper production of switching device, multi-phase BLDC Motor for high speed, high output power is being actively pursued to produce. In this paper 7-Phase BLDC Motor drive system is designed and Vector modulator is studied.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.184-189
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• 2014

This paper presents a multi-objective optimization approach to design rotor slot geometry of three-phase squirrel cage induction machine to achieve NEMA design D torque-speed (T-S) characteristics with high efficiency. The multi-objective Particle Swarm Optimization (MOPSO) algorithm combined with the adaptive response surface method and Latin hypercube sampling strategy is applied to obtain the Pareto optimal designs. In order to demonstrate the validity of the suggested optimal algorithm, an application to rotor slot design of three-phase induction motor is presented.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1058-1063
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• 2004

This paper presents a new approach regarding thermal characteristics associated with a design of the high efficiency motor. Electrical conduction materials, such as coil and aluminum embedded in the core generate high heat exerting negative influence on both lifetime and performance of machine. Thus, it is necessary to design high efficiency motor considering heat transfer in order to improve motor performance and to be protected against overheating. In this paper, firstly, numerical analysis of electromagnetic field is carried out by the nonlinear transient finite element method (FEM). Secondly, the linear static FEA of magneto-thermal field is implemented by applying source current computed by the nonlinear transient analysis. FE results are validated in terms of electromagnetics and heat transfer by experiments. And then, the pseudo-transient topology optimization using a multi-objective function is performed. The proposed method is applied to a squirrel cage single-phase induction motor of the scroll compressor.

• Journal of the Korean Magnetics Society
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• v.27 no.1
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• pp.9-17
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• 2017

A multi-phase electric machine has gained distinct interest due to its high reliability compared to a three-phase structure, and in this paper, self and mutual inductances in a five-phase permanent magnet synchronous machine (PMSM) are estimated by an analytical method. Recently, most of high-performance operations are implemented by field oriented control and/or direct torque control, and inductance for those controls is one of the key parameters in the voltage equation of phase windings. Winding function theory (WFT) is employed to calculate the inductance of phase windings, and it is verified that the result of the analytical method has a deviation of approximately 3 % compared to finite element analysis. Finally, in this paper, the way to obtain direct and quadrature inductance values are introduced from the analytical inductance calculated by WFT.

• Journal of Korea Society of Industrial Information Systems
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• v.25 no.5
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• pp.49-57
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• 2020

Conventional electric motors are not suitable for aircraft because of their large size and weight. High-temperature superconducting (HTS) motors have high current density, high magnetic field density, and low loss, so they can significantly reduce the size and weight compared to general electric motors. This paper presents the conceptual design and analysis results of HTS motors for electric propulsion in future aircraft. A 2.5 MW HTS motor with a rotational speed of 7,200 RPM was designed and the specific power (kW/kg) was analyzed. The operating temperature of the field coil of the HTS motor is 20K in consideration of LH2 cooling. The stator winding were connected in a multi-phase configuration and Litz wires were used to minimize eddy current losses. As a result, it was confirmed that the specific power of the motor is about 18.67 kW/kg, which is much higher than that of the conventional electric motor.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.500-504
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• 1997

Current source inverter drives of auto sequentially commutated type are very popular in high power applications, because of simple power circuit configuration with four quadrant operation. But the six-step current output create harmonic problems and the input power factor of such a drive is not always good. In this respect pulse width modulated drives using gate turn off thyristors ( GTO ) are finding application, especially in traction drives. However the switching and snubber loses of a GTO do not permit the inverter switching frequency go beyond a few hundred hertz.This will again introduce low frequency harmonic problems. Multi level inverters of the 3-level and 5-level can be considered as an alternative to overcome the low switching frequency harmonic problem of the 2-level GTO inverters. But with multi level inverters the complexity of the power circuit increases. In this paper a combination of multi level ( 2-level and 3-level ) inverters and multi phase induction motor ( 3-phase and 6-phase) configurations are presented for high power VSI drives for traction applications with reduced inverter switching frequency requirements coupled with reduced voltage rating for the power switch.

• Journal of Electrical Engineering and Technology
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• v.7 no.6
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• pp.948-953
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• 2012

The characteristics of an induction motor vary with the number of parameters and the performance relationship between the parameters also is implicit. In case of the induction motor design, we generally should estimate many objective physical quantities in the optimization procedure. In this article, the multi objective design optimization based on genetic algorithm is applied for the three phase induction motor. The efficiency, starting torque, and material cost are selected for the objectives. The validity of the design results is also clarified by comparison between calculated results and measured ones.

• 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.