• Journal of Advanced Marine Engineering and Technology
• /
• v.31 no.8
• /
• pp.983-989
• /
• 2007

This paper decribes multi-phase BLDC motor with a minimum torque pulsation among BLDC motor used for electric propulsion system. Multi-phase BLDC motor has characteristic that phase of stator has more than 3-phase. This paper is modeling two type of BLDC motor, one has 3-phase and the other has 7-phase, and it shows simulation of them comparing its characteristics. As a result of simulation, the 7-phase BLDC motor shows better performance in terms of torque pulsation. It is also found that the torque pulsation is reduced further by increasing the number of phase.

• Proceedings of the KIEE Conference
• /
• 1989.11a
• /
• pp.33-36
• /
• 1989

In designing reluctance motor, it is important to know the flux distribution of the inside of the motor. The reluctance motor which has axially laminated anisotropic(a.l.a.) rotor was proved to have high efficiency. To analyze this motor, it needs to consider the anisotropic characteristic of the rotor. This paper shows the flux distribution of the a.l.a. reluctance motor by finite element method (FEM) considering the anisotropic characteristic and the saturation of the core. And this paper shows the static torque for the variation of the stator dimension. This will be helpful to design the a.l.a. switched reluctance motor.

• Journal of Korean Society for Quality Management
• /
• v.42 no.1
• /
• pp.91-109
• /
• 2014

Purpose: This study compares quality crisis and management at Hyundai Motor in the late 1990s and Toyota Motor in the late 2000s. We can expect to induce more meaningful policy implications in quality management from this in-depth comparative case study. Methods: This study compares two cases at Hyundai and Toyota Motor how to overcome quality crisis based on the OESP (Organization-Environments-Strategy- Performance) model. Results: Hyundai Motor shows centralized approach based on the asymmetric organizational culture and the entrepreneurial leadership but Toyota shows decentralized, systematic approach based on the steady state leadership and symmetric organizational culture. The CEO's leadership have proved to be one of the important factors at both companies. Conclusion: The effective quality management in global contexts has become more and more difficult for the 'complexity explosions' in automobile industry. As a consequence, the future competitive edge of world automobile industry will come from the effective quality management of products in global contexts.

• Proceedings of the KIEE Conference
• /
• 2006.10c
• /
• pp.312-314
• /
• 2006

This paper describes performance of the modified gain scheduling controller by speed control of a DC motor. The modified gain scheduling controller can perform tracking at more than one equilibrium points. The modified gain scheduling controller which considers transient response according to added zero shows better result of tracking performance than the unmodified gain scheduling controller shows.

• Annals of Clinical Neurophysiology
• /
• v.13 no.1
• /
• pp.38-43
• /
• 2011

Background: In the brain, the dominant primary motor cortex (M1) has a greater hand representation area, shows more profuse horizontal connections, and shows a greater reduction in intracortical inhibition after hand exercise than does the non-dominant M1, suggesting a hemispheric asymmetry in M1 plasticity. Methods: We performed a transcranial magnetic stimulation (TMS) study to investigate the hemispheric asymmetry of paired associative stimulation (PAS)-induced M1 plasticity in 9 right-handed volunteers. Motor evoked potentials (MEPs) were measured in the abductor pollicis brevis (APB) muscles of both hands, and MEP recruitment curves were measured at different stimulation intensities, before and after PAS. Results: MEP recruitment curves were significantly enhanced in the dominant, but not the non-dominant M1. Conclusions: These results demonstrate that the dominant M1 has greater PAS-induced plasticity than does the non-dominant M1. This provides neurophysiological evidence for the asymmetrical performance of motor tasks related to handedness.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.7
• /
• pp.163-170
• /
• 2002

This paper presents some measures far the optimization of the thermal behavior of linear motors, which are used as a high speed feed mechanism in machine tools. Thermo-Sandwich-Construction using two cooling circuits and an insulation layer shows an effective cooling system for linear motors. Conducting sheet can be also used to reduce heat flow from linear motor to machine table. Cooling pipe is a simple and effective cooling system for the secondary part of synchronous linear motor. Through the combination of the Thermo-Sandwich-Construction, conducting sheet and cooling pipe the thermally optimized linear motor shows a well improved thermal behavior in comparison with the prototype motor.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.49 no.11
• /
• pp.742-748
• /
• 2000

This paper presents a numerical method to analyze the electromechanical-coupled field in the spindle motor of a computer hard drive and investigates dynamic response due to the electromechanical excitation, i.e. unbalanced magnetic force and centrifugal force for the rotational asymmetric motor. Magnetic field is calculated from Maxwells equation and voltage equation by introducing nonlinear time-dependent finite element analysis. Mechanical motion of rotor is calculated by solving Newton-Euler equation. Electromechanical excitation and dynamic response are characterized by analyzing the free response of a rotating rotor and Fourier analysis of the excitation force and resulting vibration of a rotor. It shows that centrifugal force produces the unbalanced magnetic force even in the rotational symmetric motor. It also shows that resonance produces quite considerable vibration even when the high excitation frequency with small amplitude matches with the natural frequency of the spindle motor.

• 전기의세계
• /
• v.21 no.2
• /
• pp.20-24
• /
• 1972

The transient stability of the synchronous motor is generally improved by damper winding or flywheel. However the synchronous motor at full load will be pulled out from normal operation state when the period of power failure exceeds approximately ten cycle per second. This paper studies the method of improving the stability of synchronous motor by equipping the phase slipping switch between the motor and power source. This paper shows the motor does not pull out, which results from the decrease of power angle to about 30 electrical degrees by means of the switch even when the relatively long period of power failure brings the power angle to some 150 electrical degrees.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.804-805
• /
• 2006

Electric scroll-compressor drives are commonly used for e.g. home appliance cooling units. The recent development of hybrid cars with internal combustion engine in combination with electrical propulsion requires new solutions to be able to cool the passenger compartment of cars at stand-still. Both application areas demand efficient motor drives to reach good economy and efficient use of limited battery power as well as competitive volume/weight for a given output. The BLDC motor is a controllable and efficient solution. A major part of the motor is the soft-magnetic core. The powder based $Somaloy^{(R)}$ material shows high resistivity and induction as the result of engineered iron particles with in-organic coating. The unique features of compacted $Somaloy^{(R)}$ components can be utilized to enhance the shape and total volume of the BLDC motor with at least maintained efficiency compared to the use of traditional laminated steel sheet cores. A careful design of the $Somaloy^{(R)}$ components can also simplify assembly and positively influence the coil configuration. This study shows a comparison between a typical laminated BLDC motor and a redesigned, $Somaloy^{(R)}$ based version adapted for a scroll-compressor application.

• Proceedings of the KIEE Conference
• /
• 2004.05a
• /
• pp.19-21
• /
• 2004

This paper considers pulse width modulation (PWM) methods which are used in 3-phase brushless DC motor controller. Due to many disadvantages of bipolar PWM method, unipolar PWM method is mostly used in industrial field. In constant speed control application, the unipolar PWM method shows a good performance of speed control. But in the wide range of speed control application, it shows a poor performance especially when deceleration is needed. So we propose hybrid PWM method that utilizes two PWM methods according to the sign of speed controller output. The simulation and experimental result shows that the proposed method improves a speed control performance of the brushless DC motor which is applied to industrial sewing machines.