• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.27-29
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• 2001

In this paper, we study in magnetizing the NdFeB magnet which is inserted in a squirrel cage rotor. The inserted NdFeB magnet need much more magnetizing flux than that of ferrite magnet. Also the eddy current flowing in rotor bar disturbs the magnetizer in magnetizing the NdFeB magnet. The existing magnetizing yoke is designed by increasing the coil turn. But we recognize that only by increasing the coil turn it is impossible to make NdFeB magnet magnetized fully. Hence, in this paper we propose the method of increasing magnetizing flux by reducing the rotor bar area.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.239-243
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• 2010

This paper deals with the optimum design criteria for the premium efficiency of 250 kW traction induction motor, using response surface methodology (RSM) and finite element method (FEM). The focus of this paper is found firstly a design solution through the comparison of torque according to rotor bar shape, rotor dimensions variations. And secondly a mixed resolution with central composite design (CCD) is introduced and analysis of variance (ANOVA) is conducted to determine the significance of the fitted regression model. The proposed procedure allows to be optimized the rotor copper bar shape, rotor slot, rotor dimensions starting from an existing motor or a preliminary design.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.8
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• pp.370-376
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• 2005

The single-phase induction motor is simple and durable, but the efficiency is low. Therefore, electric motors like HLDC and LSPM(line-start permanent magnet motor) that use the permanent magnet have been studied. The most advantages of single-phase LSPM is having the same stator as the stator of the single-phase induction motor and permanent magnets are just inserted in the squirrel cage rotor of the single-phase induction motor. But the characteristics of single-phase LSPM synchronous motor has very complex characteristics until the synchronization and if the design is not suitable, the single-phase LSPM synchronous motor cannot be synchronized. We designed a single-phase LSPM using the same stator and winding as the conventional single-phase induction motor, but newly designed the permanent magnets considering air gap magnetic flux density. The transient characteristics of the single-phase LSPM is not good because of a magnetic breaking torque, however, it can be improved by redesigning the rotor bars. We are proposed the design method of rotor bar for the single-phase LSPM to start softly and to make synchronization easily.

• Journal of Mechanical Science and Technology
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• v.20 no.7
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• pp.972-980
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• 2006

In general, to send out natural gas via a pipeline network across the nation in LNG terminal, high-pressure cryogenic pump supply highly compressed LNG to high-pressure vaporization facilities. The Number of cryogenic pumps determined the send-out amount in LNG receiving terminal. So it is main equipment at LNG production process and should be maintained on best conditions. In this paper, to find out the cause of high vibration at cryogenic pumps-motor system in LNG terminal, vibration spectrum analysis and motor current signature analysis have been performed together. Through the analysis, motor rotor bar problems are estimated by the vibration analysis and confirmed by the current analysis. So, it is demonstrated through the case study in this paper, how performing vibration analysis and current signature analysis together can reliable diagnosis rotor bar problems in pump-motor system.

• Journal of Electrical Engineering and Technology
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• v.8 no.2
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• pp.288-294
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• 2013

The diagnosis of motor failures using an on-line method has been the aim of many researchers and studies. Several spectral analysis techniques have been developed and are used to facilitate on-line diagnosis methods in industry. This paper discusses the first application of a motor flux spectral analysis to the identification of broken rotor bar (BRB) faults in induction motors using a multiple signal classification (MUSIC) technique as an on-line diagnosis method. The proposed method measures the leakage flux in the radial direction using a radial flux sensor which is designed as a search coil and is installed between stator slots. The MUSIC technique, which requires fewer number of data samples and has a higher detection accuracy than the traditional fast Fourier transform (FFT) method, then calculates the motor load condition and extracts any abnormal signals related to motor failures in order to identify BRB faults. Experimental results clearly demonstrate that the proposed method is a promising candidate for an on-line diagnosis method to detect motor failures.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.331-338
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• 2002

An inverter-fed induction is driven by a harmonic voltage source so that it is necessary to be analysed by time-stepping F.E.M. But it takes so long time that disadvantageous to design. This paper presents a simple analysis method for inverter-fed induction motor using FEM and harmonic equivalent circuit. First, the rotor bar resistance and the leakage reactance are determinated by FEA for 1 slot region in rotor to consider the skin effect and the saturation. Secondly, the characteristic of the motor is analyzed by the harmonic equivalent circuits consisting of the obtained parameters from the FEA. This method is carried out to analyze an induction motor driven by the sinusoidal voltage and the inverter. The results are verified by comparing with those of the time-step F.E.A and the experiment.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.37-44
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• 2014

This paper proposes a new diagnosis algorithm to detect broken rotor bars (BRBs) faults in induction motors. The proposed algorithm is composed of a frequency signal dimension order (FSDO) estimator and a fault decision module. The FSDO estimator finds a number of fault-related frequencies in the stator current signature. In the fault decision module, the fault diagnostic index from the FSDO estimator is used depending on the load conditions of the induction motors. Experimental results obtained in a 75 kW three-phase squirrel-cage induction motor show that the proposed diagnosis algorithm is capable of detecting BRB faults with an accuracy that is superior to a zoom multiple signal classification (ZMUSIC) and a zoom estimation of signal parameters via rotational invariance techniques (ZESPRIT).

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.3-5
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• 1999

This paper deals with the effect on the stress and deformation of the rotor bar of a cage induction motor by the thermal stress, centrifugal force and electromagnetic force. We use both the thermal network method(TNM) and the finite element method(FEM) to analyze the temperature and stress of the rotor.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.631-632
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• 2006

This paper is written by research for the transient characteristics of the Single-phase Line-start permanent Magnet. The Single-phase Line-start permanent Magnet is most likely to substitute for Single-phase Induction Motor which is used about many appliance currently, because that has good points. For example, It has a Line-start of ability and a High-efficiency. And it need not power convergence device. The rotor of The Single-phase Line-start permanent Magnet has cage-bar with permanent magnet. This motor is started by cage-bar. When it entered synchronous condition, the rotor is rotated by the permanent magnet. But the design of the permanent magnet is very important, because the breaking torque of the permanent magnet interrupt to start a rotor. Finally, if Flux Barrier is not concerned, we do not get result of our object. Therefore this thesis is concerned about Flux Barrier.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.3-5
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• 2003

This paper deals with the characteristics of a capacitor-run single-phase induction motor by changing of conductor bar numbers. The Finite Element Method (FEM) is used to analyze the starting characteristics according to the rotor initial starting point about conduction bar and the characteristic analysis at the rated condition is calculated by equivalent circuit based on symmetry coordinate theory Finally, the analysis results of the analysis models have different conductor bars in their rotor are compared.