• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.7-10
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• 1987

• Journal of Drive and Control
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• v.1 no.3
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• pp.32-38
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• 2004

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.212.2-212.2
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• 2008

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.226-232
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• 2006

This paper presents the parameter measurement methods for high performance drive of induction motors, which are suitable for the self-commissioning function of commercial inverters. In this study, some factors that affect the accuracy of parameter measurement are examined. Measuring methods and conditions that are best fit to each parameter measurement procedure are then proposed. All the measurement procedures can be done without any auxiliary equipment, so that those can be easily adopted as self-commissioning functions of commercial inverters. To improve the measuring accuracy, least square approximation methods are adopted during the measurement procedure. The validity of the proposed methods are confirmed through experiments.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.7 no.2
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• pp.102-108
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• 2007

The issues of preventive and condition-based maintenance, online monitoring, system fault detection, diagnosis, and prognosis are of increasing importance. This study introduces a technique to detect and identify faults in induction motors. Stator currents were measured and stored by time domain. The time domain is not suitable for representing current signals, so wavelet transform is used to convert the signal; onto frequency domain. The raw signals can not show the significant feature, therefore difference values are applied. The difference values were transformed by wavelet transform and the features are extracted from the transformed signals. The dynamic time warping method was used to identify the four fault types. This study describes the results of detecting fault using wavelet analysis.

• Journal of Power Electronics
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• v.6 no.4
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• pp.340-346
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• 2006

A high efficiency drive technique for synchronous reluctance motors (SynRM) using a neural network (NN) is presented in this paper. High efficiency drive condition depends on the mathematical model of SynRM. A NN is employed as an adaptive model of SynRM. The proposed high efficiency drive technique does not require an accurate mathematical model of SynRM. Moreover, the proposed method shows robustness against machine parameter variations because the training algorithm of the NN is executed on-line. The usefulness of the proposed method is confirmed through experimentation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.10
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• pp.1065-1072
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• 2008

A HDD adopts a sensorless brushless DC (BLDC) motor as a spindle motor. Because there is no direct sensor measuring rotor position. open loop commutations with inductive sensing are used to increase the rotor speed up to a certain speed where the zero crossings of the back electromotive force (EMF) voltage are measurable. Therefore, successful open loop commutations are necessary for the stable start-up control of the spindle motors. In this paper, the time scale and the number of the open loop commutations are employed for design parameters to guarantee robustness to torque constant variation and initial rotor position. The design results are verified by experiments on a very low current start-up of the spindle motor with various environment. The experimental results show that the design results can decrease the start-up failure rate considerably.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.225-228
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• 2009

The simulated indoor pass-by noise measurement system is the tool to measure and evaluate the pass-by noise at the test laboratory, without doing measurement at the field. This measurement system can realize the precision measurement under the specific condition and overcome the limitations of the field measurement, i.e. weather conditions, repeatability, .. This measurement system is done in time domain process using the array techniques, which synchronizes the time signals. The reliability of the obtained result depends on the array shapes, which can generate the moving source effect. In this paper, the validations are checked focusing the time domain synchronization of the signals with the optimum microphone array shape.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.135-136
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• 2002

Molybdenum Nitrided (MoNx) films were deposited by DC planar magnetron sputtering. Silicon wafers and real nitrided stainless steel piston rings are employed as substrates. 12 different combinations of nitrogen and argon partial pressure, from 1:7 to 7:1, were applied to deposit MoNx films. X-ray diffraction (XRD) was used to determine the phase structures of films. When nitrogen vs. argon partial pressure is 1:7, the film is mainly $Mo_2N$ phase. With increase of nitrogen partial pressure, MoN phase emerges, but $Mo_2N$ phase still exists. Composition analysis with atomic emission spectrometry (AES) also agreed with this. The films have very high nanohardness (max 2400Hv) and good adhesion to the substrates.

• Journal of National Security and Military Science
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• s.1
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• pp.311-343
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• 2003

In this paper, we propose a generalized disturbance torque suppression control scheme of servo motors for missile fin actuators. Our controller consists of both a model based feed-forward controller and a stabilizing feedback controller. The feed-forward controller is designed such that the output of nominal plant tracks perfectly the reference position command with a desired dynamic characteristics. The feedback controller stabilizes the overall closed loop system. Furthermore, the feedback controller contains a free function that can be chosen arbitrary. The free function can be designed so as to achieve both the suppression of disturbances and the robustness to model uncertainties. In order to illuminate the superior performance of our control scheme to the conventional ones, we present some simulation results.