• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.795-797
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• 2001

Voltage varing Fate dv/dt which is applied to induction motor usually makes unnegligible leakage current and it flows through stator winding and motor frame. This kind of harmonic leakage current makes effect on power source and cuases electromagnetic trouble because the motor frame has earth. Therefore in this study, a high frequency induction motor model is developed and analyze the motor performance to explain the phenomena. Inverter model is also developed and is combined with the motel model to prepare the basis of the high frequency effects on inverter fed induction motor.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.1
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• pp.50-56
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• 2012

The Multi D.O.F spherical motor can drive rotating as well as tilting three degree of freedom with one motor. Existing three degree of freedom to drive with three motors that are connected by gears and belts, that will be too large size and big loss at gears and belts. So Reducing system size and improving efficient is using the Multi D.O.F spherical motor in three degree of freedom systems. For this reason, efficiency of Multi D.O.F spherical motor is one of the important performance indiccators. In this paper presented that how to improve the efficiency of the Multi D.O.F spherical motor. The fist of method is using the stator iron core's material with high permeability and resistivity for reducing the eddy current loss. However, it was the disadvatages of motor-making and economic. So author propose the resonable method of reducing the eddy current loss in the stator iron core. That is using the rotor with double-air gap.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.177-180
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• 2000

The accurate values of parameters of an induction motor are required for its high performance control. So far many methods using current sensors voltage sensors and speed sensor have been developed. This paper proposes an identification method of parameters of induction motor only using current sensors.

• Journal of Electrical Engineering and Technology
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• v.2 no.4
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• pp.500-504
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• 2007

In this paper, the induction motor rotor fault diagnosis system using current signals, which are measured using axis-transformation method, and speed, which is estimated using current information, are presented. In inverter-fed motor drives unlike line-driven motor drives the stator currents have numerous harmonics components and therefore fault diagnosis using stator currents is very difficult. The current and speed signal for rotor fault diagnosis needs to be precise. Also, high resolution information, which means the diagnosis system, demands additional hardware such as low pass filter, high resolution ADC, encoder and etc. Therefore, the proposed axis-transformation and speed estimation method are expected to contribute to low cost fault diagnosis systems in inverter-fed motor drives without the need for an encoder and any additional hardware. In order to confirm validity of the developed algorithms, various experiments for rotor faults are tested and the line current spectrum of each faulty situation using Park transformation and speed estimation method are compared with the results obtained from fast Fourier transforms.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.299-304
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• 2003

This paper proposes an algorithm to estimate the screw torque from parameters of induction motor and current of DC motor without strain gage and torque cell. The parameters of friction torque search for damping ratio and electromotive force constant use the motor torque and angula speed signals be generated in the induction motor, make use of oscilloscope and stroboscope for precise measured of experimental data, measured physical parameters through experimental. In addition the screw torque estimated use of measured current signals from induction moor. The results, theory and simulation recognized well coincidence.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.4
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• pp.259-266
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• 1987

In order to drive motor control system precisely, the motor is to be controlled by mmfs and current with sinusoidal waveforms. In this paper the Delta Modulation (DM) Technique is used for generating PWM pulse with sinusoidal waveform. However the motor currents yet contain odd harmonics due to leakage inductances, speed and exitation. To reduce harmonics, the parameter adaptive control method is introduced. That is, Req.C parameter of Delta Modulator is controlled adaptively by parameter adaptor. The adaptive signal is achieved by the difference between motor current and reference waveform, and this signal is converted to the voltage commend signal by adaptive mechanism. The test reslts show that this system is operated smoothly over a wide range of motor speed and motor current is controlled to be sinusoidal waveform adaptively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1142-1147
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• 2002

For the evaluation of the DC motor noise and vibration, usually it is rely on human feeling because some kinds of noise are not definitely represented by measurement Instrument such as sound meter. But when we consider time signal of the noise and vibration. It is possible to represent them. And in this paper. it is suggested to study output current shape of the motor because it Is the source to make speed and torque variation of the motor. If the current shape is not stable. it makes operating state of the motor unstable and produces noise and vibration. By analyzing signal at time and frequency of noise and vibration and current shape. it is possible to automation of the noise and vibration measurement in the Production line.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.6
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• pp.292-297
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• 2002

This paper proposes a sensorless drive of a permanent magnet synchronous motor. In general EMF is used to calculate the current of Permanet Magnet Synchronous Motor(PMSM). However the current has a lag component by a time constant. So it is difficult to directly calculate a position angle. To estimate the position using the current without a lag component in this paper, the controller calculates the motor current by using a superposition principle in the equivalent circuit and then compensates lag component with a time constant of the motor. Therefore the estimated motor current without a lag compoent can be obtained and it is used to calculate the rotor position indirectly. In order to confirm the effectiveness of the proposed algorithm, experimental results are shown in detail.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.507-512
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• 1999

In modern engineering practice, the grinding process is one of the most important and widely used operations for the precision finishing of components. In this paper, machining characteristics of external plunge grinding were investigated by using spindle motor current signal through hall sensor. Grinding experiments were performed in terms of various grinding conditions such as wheel speed, workpiece speed, infeed rate and spark-out time with conventional vitrified bonded WA wheel. The relationship between spindle motor current signal and metal removal rate in terms of infeed rate was induced the by analyzing spindle motor current signal.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.8
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• pp.675-683
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• 2004

The motor current signature provides an important source of the information for the faults diagnosis of three-phase induction motor. The theoretical principles behind the generation of unique signal characteristics, which are indicative of failure mechanisms, are Presented. The fault detection techniques that can be used to diagnose mechanical Problems, stator and rotor winding failure mechanisms, and air-gap eccentricity are described. A theoretical analysis is presented which predicts the presence of unique signature patterns in the current that are only characteristics of the fault. The predictions are verified by experimental results from a special fault Producing test rig and on-site tests in a steel company. And this study have made new diagnostic algorithm for the operating induction motors with the test results. These developments are including the use of monitoring and analysis of electric current to diagnose mechanical and electrical problems and gave the precise test results automatically.