• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.571-577
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• 2003

This research proposes a finite element method to determine the natural vibration characteristics of the spinning disk-spindle system in a HDD including the flexibility of supporting structure. Finite element equations of each substructure are derived with the introduction of consistent variables to satisfy the geometric compatibility at the internal boundaries. The natural frequencies and modes from the global asymmetric matrix equations of motion are determined by using the implicit restarted Arnoldi iteration method. The validity of the proposed method is verified by the experimental modal testing. It also shows that the flexibility of base plate plays an important role to determine the natural frequencies of the spinning disk-spindle system in a HDD.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.171-171
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• 1999

In case of field weakening region torque is directly affected by flux. In this region the flux reference is decreased inversely proportional to the rotor speed. As the flux is decreased the magnetizing inductance is normally increased. The increased magnetizing inductance limited voltage for controlling current. In this paper, measuring q axis voltage in field weakening region magnetizing inductance in flux calculating can be readjusted. Computer simulation and experiment results demonstrate the efficacy of the proposed method. Proposed algorithm is expected to the application of the adjustable drive system in the spinning and weaving field.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.59-65
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• 2008

High-speed electrical motor has been studied for several applications, i.e. for direct-drive systems of centrifugal compressors and turbo blowers. This paper deals with a design consideration of electromagnetic, mechanical and thermal limits of high-speed induction motor for turbo blower. Basic design concept of high-speed motor was proposed. As the motor is to be operated at high speed, the losses are quite different from conventional low-speed machines. Especially, the increases of rotor eddy current and friction losses could lead to an overheated motor. So, we suggested a special cooling system to reduce temperature rise. And, based upon this design concept, the prototype induction motor(37[kW], 45,000[rpm]) for high-speed turbo blower was designed and 2-D electromagnetic field analysis was implemented. Finally, criteria to evaluate the characteristics of high-speed induction motor have been proposed and tested.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.27-29
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• 2005

This paper studies particularly applicable method for sensorless Permanent Magnet Brushless DC(PMBLDC) Motor drive system. The waveform of the motor internal voltages (or back emf) contains a fundamental and higher order frequency harmonics. Therefore the third harmonics. component is extracted from the stator phase voltage. The resulting third harmonic signal keeps a constant phase relationship with the rotor flux for any motor speed and load condition. In addition, a simple starting method and a speed estimation approach are also proposed.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.234-236
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• 2005

In this paper, an instantaneous speed observer with a reduced order is proposed to implement an indirect control for an motor with excellent dynamic stability and performance in a very low speed region. The proposed observer can estimate the instantaneous speed in very low speed region and simplify the system configuration by adopting a least order load torque-inertia observer to estimate the load torque and the rotor speed. Simulation are carried out to illustrate the performance of the proposed estimator at very low speed.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.40-42
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• 1999

High-speed brushless permanent magnet machines are good for compressor and aerospace applications, etc, since they are conductive to high efficiency, high power density, small size and low weight. This paper describes a diametrically magnetized PM motor with the rating of 4.3kW and 50000 rpm fur high-speed drive applications. To bear strong stress from high speed, rotor was designed cylindrical structure, was magnetized diametrically permanent magnet. The performance characteristic of motor was evaluated by means of FEA(Finite Element Analysis), no-load test And then, in order to find back-EMF constant, used FEA, search coil.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.978-980
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• 2000

Sensorless PMSM is much studied for the industrial applications and home appliances because, a mechanical sensor reduces reliability and increases cost. Two types of instantaneous torque controls are basically used for high performance variable-speed a.c. drive : vector control and direct torque control. This paper investigates speed sensorless control of PMSM using direct torque control. The switching of inverter is determined from SVPWM realizing the command voltage which is obtained by flux error and measured current without d-q transformation. The rotor speed is estimated through adaptive observer with feedback loop. The simulation and experimental results indicate good performances.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.385-387
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• 1999

Brushless DC Motors are widely used because of their high power ratio and easy control. But the brushless DC Motors need rotor Position- and speed- sensor such as encoder, resolver and hall sensor. The position sensor has present several disadvantages from the standpoint of drive cost, machine size and reliability. Hall sensors are used generally because of low cost but their operating temperature is limited up to $75^{\circ}C$ because of sensitivity of temperature. Now a day many research projects are on the development of sensorless brushless DC motors to correct these disadvantages. In this paper, characteristics such as starting, change of speed and load of a sensorless brushless DC motor are investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.4
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• pp.596-602
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• 2008

The cooling system is one of the most concerning factor for the reliability of the electric propulsion ship. Generally, a drive system operation in higher temperature decreases the device's reliability and power efficiency. The management of power loss and temperature of switching devices is indispensable for the reliability of the power electric system. In this paper, the switching devices are molded by IGBT, and the propulsion system is consisted of MIIR(Motor with Inverter Internal to Rotor). The system composition interacts with each other to calculate the loss and temperature of device. The calculation result is used for modeling and designing of the control and monitoring system for the electric propulsion system.

• Journal of Magnetics
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• v.22 no.1
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• pp.93-99
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• 2017

The effort attempts to investigate the influence of various non-oriented electrical steel sheets on the core loss of a switched reluctance motor (SRM). The core loss of the motor inherits a strong correlation with flux density and permeability of the material. The study involves the use of laminated 2.7 % high silicon steel suitable for the motor in view of its higher flux density and lower core loss. The accurate prediction of core loss leaves way to suggest measures for improving the performance of the SRM. The dynamic simulation measurements of a 1.5 kW, three-phase 12/8 SRM involve the finite element method (FEM) and use the data obtained experimentally from Epstein frame. The closeness of the simulated and hardware results obtained with laminations of M400-50A, DI MAX-M19 and DI MAX-M15 both for the stator and rotor, espouse a greater significance to the findings in terms of the core loss density and forge new dimensions for its use in the drive industry.