• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.983-984
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• 2011

An effective estimation method of equivalent circuit parameters of three-phase induction motor by using FEM is presented in this paper. Arbitrary three torque-speed points at asynchronous speed on the torque-speed curve are required by using time-stepping FEM, then the equivalent circuit parameters of IM can be calculated rapidly with presented method. After obtaining the equivalent circuit parameters, the general analysis method based on equivalent circuit can be used to get entire torque-speed curve very quickly. Although the purely numerical method such as FEM also can estimate torque-speed curve directly and accurately, however, usually this process is time consuming.

• 전기의세계
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• v.21 no.4
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• pp.15-21
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• 1972

For the conventional DC machine, the armature MMF is negligible compared with field MMF except when the machine is under heavy load or transient conditions. During the motor starting or reversal, the transient armature current and corresponding MMF effect the flux density of each pole in the machine magnetic circuit. However, the circuit flux density is restored to normal values by the field winding MMF after the transient armature current dies in an electromagnetic DC motor. Permanent magnet servomotor have no field windings about the circuit poles to restore circuit flux density through the demagnetized part of each pole after the transient armature MMF dies, and portions of the magnetic circuit stay permanently demagnetized. Thus the problem of stabilizing a magnet pole piece under the influence of the transient armature current need attentions. This work present the recoil operation of the servomotor with PM poles in conjunctions with the influence of the armature reaction effect. The development of an analytical and quantatative study is presented for predicting the regime of the recoil operation under this condition.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.8
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• pp.455-460
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• 1999

A novel zero-voltage-transition (ZVT) PWM converter for switched reluctance motor (SRM) drives is proposed. A simple auxiliary circuit which consists of one active switch, one resonant inductor, and three diodes provides ZVS condition to all main switches and diodes allowing high frequency operation of the converter with high efficiency. The auxiliary circuit is placed in parallel with the main power flow path and thus it handles only a small fraction of the main power. So, the power rating of the auxiliary circuit can be very small (about 30% of main power). So, the auxiliary circuit can be realized with small power rating and low cost. Operation, features and characteristics of the proposed converter are illustrated and verified on a 1.5 kW, 50 kHz IGBT based (a MOSFET for the auxiliary with) experimental circuit.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.325-327
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• 1995

A new gate drive circuit of classic converter for a switched reluctance motor is presented. Conventional gate drive circuit usually consists of the isolated power supplies and signal transferring devices for isolation, such as photo coupler, pulse transformer, and gate drive chips. The proposed gate drive circuit consists of resistors, capacitors, and zenor diodes without isolated power supplies, that make the drive circuit simple and reduce the material cost. The operational modes are classified and analyzed. The characteristics of the phase current and the gate signal of upper switches is investigated with the variation of duty ratio through the experiments.

• Journal of Mechanical Science and Technology
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• v.20 no.12
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• pp.2087-2093
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• 2006

In this paper, auto focus actuator, which is used to move a lens module in the mobile phone having a camera module, is developed. Camera module containing auto focus actuator requires to minimize total size because of characteristics of the application area such as mobile phone, digital camera, and personal digital assistant. There are stepping motor, voice coil motor, and piezoelectric motor as auto focus actuator. In this paper, voice coil motor having new electromagnetic configuration is proposed. And actuator using proposed voice coil motor is developed by optimal design method using magnetic circuit analysis. The sectional area of the developed actuator is reduced to 32.4% compared with actuator using general electromagnetic configuration. From the performance test, the developed actuator has moving stroke of 0.64 mm for 2.1 volt, hysteresis of 40 $\mu$m, full stroke current of 54 mA, and unit step motion of 3 $\mu$m.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.2
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• pp.190-196
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• 2007

This paper presents the 3D finite element analysis of the Contact-less Power Supply(CPS) with linear servo motor. The primary, secondary self and leakage inductances of the contact-less power supply and the capacitances of a resonant circuit are calculated by the finite element analysis using current source. The voltage source is used to do accurate analysis of the characteristics of the contact-less power supply. The CPS with the linear servo motor is proposed. The characteristics analysis of the contact-less power supply considering the linear servo motor is done.

• Journal of the Korean Society of Safety
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• v.9 no.4
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• pp.49-57
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• 1994

In this paper, a speed controller using a controller is implemented and applied to a DC motor for FA ( Factory Automation ). The objective of this paper treats the analytical and experimental studies on the improvement of control circuit and control method using a SCR-LEONARD circuit for the speed control of DC motor. This system is concerned with stabilization of single input or single output systems, so the plant (SCR-LEONARD+DC motor) is simplified to the first order system. The parameters for the PID controller are obtained by the transient-response tunning method, and this control scheme has a backward-shift operator. The control algorithms (Chopper＋transient response tunning) is used to check the performance of PID Controller through Computer simulations and experiments. The good experiment results show that the direct control of the DC motor applied to industrial field such oi factory automation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1231-1235
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• 2007

This paper presents the dynamic characteristics of a linear brushless dc (BLDC) motor with permanent magnet excitation for the precision conveyor according to the load condition. Dynamic performance of the linear BLDC motor driven with 6 step inverter such as thrust force and speed is simulated by finite element method coupling with external circuit and measured for the prototype motor. The results of finite element analysis are compared to the experimental results and verify reliability.

• Proceedings of the KIPE Conference
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• 1998.11a
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• pp.18-22
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• 1998

A PWM inverter with an induction motor often has a problem with a high frequency leakage current that flows through stray capacitor between stator windings and a motor frame to ground. This paper presents an equivalent circuit for high frequency leakage currents in PWM inverter feeding an induction motor, which forms an LCR series resonant circuit. A conventional common mode ckoke or reactor in series between the ac terminals of a PWM inverter and those of an ac motor is not effective to reduce the rms and average values of the leakage current, but effective to reduce the peak value. Furthermore, this paper proposes a leakage current damper which is different in damping principle from the conventional common mode choke. It is shown theoretically and experimentally that the leakage current damper is able to reduce the rms value of the leakage current to 25%, where the core used in the leakage current damper is smaller than that of the conventional common-mode choke

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.563-566
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• 1989

Drive malfunction take many forms and every possible one must be protected against. Until recently a separate analog device was needed for each type of malfunction. In this approach to simplified, more reliable motor-circuit protection and control, a microprocessor's digital controller for motor control center simultaneously examine most of the possible sources of circuit trouble and has more efficent functions (sequence control,display) than the conventional motor control center. The result of standard surge tests provided a realistic evaluation of the surge withstand capability of equipment.