• Proceedings of the KIEE Conference
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• 1998.11a
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• pp.168-170
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• 1998

In this paper a driving method using the microcomputer in safe driving the axial type double rotor brushless DC motor without shaft position sensor is studied. The rotor position is determined from the back-EMF passed though special filter. Starting technique which uses the motor as a synchronous motor at standstill are explained. The motor speed is controlled by changing the duty cycle of PWM. The test motor has Y-connected three-phase stator and 8-pole axial type double rotor. From the experiments, we got good performences of the proposed control system.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.4
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• pp.510-519
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• 1998

Recently, computer modelling is increasingly used as a design tool, which requires more detailed data for heat transfer coefficients in various regions of the induction motor. But there are little information about those of rotor fan and endring because of difficulty in measuring signals in rotating bodies. In the present studies, the temperature signals were precisely measured with self-developed telemetry system, which had multi-channels and high rotational speed. After some losses were compensated, the heat transfer coefficients of the rotor endring and fan surfaces were measured. Minimum heat transfer region was existed with endcap plate distance and maximum heat transfer was found at some rotor fan width. It was also studied that how the guide plate and endcap inside rib effected on the rotor heat transfer. The higher heat transfer were obtained with decreasing guide plate distance, increasing the number and height of endcap inside rib. The correlation equations of the results were obtained and compared with others. Above results of the heat transfer coefficients can be used as basic data for cooling design of the various kind of motors.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.350-357
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• 2005

This paper presents a mechanical sensorless vector-controlled system with parameter identification by the aid of image processor. Based on the flux observer and the model reference adaptive system method, the proposed sensorless system includes rotor speed estimation and stator resistance identification using flux errors. Since the mathematical model of this system is constructed in a synchronously rotating reference frame, a linear model is easily derived for analyzing the system stability, including motor operating state and parameter variations. Because it is difficult to identify rotor resistance simultaneously while estimating rotor speed, a low-accuracy image processor is used to measure the mechanical axis position for calculating the rotor speed at a steady-state operation. The rotor resistance is identified by the error between the estimated speed using the estimated flux and the calculated speed using the image processor. Finally, the validity of this proposed system has been proven through experimentation.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.260-262
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• 1998

A new method of induction motor drive, which requires not shaft encoder, is presented. This system has both torque and speed controls that are performed by vector control. The scheme is on the basis of a rotor flux speed control, which is performed by torque producing current and rotor flux, derived from the stator voltages and currents. But, there is a problem with respect to the calculated rotor flux vector, which is an integrating operation by which the rotor induced voltage is converted into the rotor flux. The calculated rotor flux does not work so that it is unstable in initial operation, as motor speed approaches zero. For the proposed rotor flux estimator, a lag circuit is employed, to which both the motor-induced voltage and rotor flux command are imposed, and it is possible to calculate even a low frequency down to standstill. We show the validity of the proposed control method through several computer simulations.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.101-103
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• 2003

This paper deals with field distributions in high speed motor with two different types of diametrically magnetized PM rotor, one is that rotor is consisted of PM and shaft, the other is that rotor has only PM. In case of high speed motor with rotor consisted of PM and shaft, this paper predicts field distributions in high speed motor according to the quality of shaft. The magnetic field solutions are derived analytically in terms of vector potential and 2-D polar coordinate system. The results are shown in good conformity with those obtained from the commonly used finite element method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1882-1888
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• 2010

It is widely known that ESA(Electric Signature Analysis) method is very useful one for fault diagnosis of an induction motor. Online fault diagnosis system of induction motors using LabVIEW is proposed to detect the fault of broken rotor bars and shorted turns in stator. This system is not model-based system of induction motor but LabVIEW-based fault diagnosis system using FFT spectrum of stator current in faulty motor without estimating of motor parameters. FFT of stator current in faulty induction motor is measured and compared with various reference fault data in data base to diagnose the fault. This paper is focused on to predict and diagnose of the health state of induction motors in steady state. Also, it can be given to motor operator and maintenance team in order to enhance an availability and maintainability of induction motors. Experimental results are demonstrated that the proposed system is very useful to diagnose the fault and to implement the predictive maintenance of induction motors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.3
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• pp.238-244
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• 2004

To monitor the torque of an induction motor using current, the accurate identification of the motor parameters is very important. In this study, the motor parameters such as rotor resistance, stator and rotor leakage inductance, mutual inductance are estimated for torque monitoring and indirect vector control. Estimated parameters are used to monitor the torque of vector controlled induction motor without any speed measuring sensor. Stator current is measured to estimate the magnetizing current which is used to calculate flux linkage, rotor velocity and motor torque. From the experiments, the proposed method shows a good estimation of the motor parameters and torque under the normal rotational speed.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.374-375
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• 2019

In this paper, In the whole industry, there is a tendency to replace brushless motors with brushless motors because of the high rate of failure in DC motors with brushes. Accordingly, many methods for driving a brushless motor have been developed and studied. In order to drive the brushless motor, it is essential to know the information about the rotor position of the motor. However, it is not possible to use a position sensor for rotor disconnection due to the structure of an electric compressor brushless DC motor. In this paper, we investigate the rotor position of the motor by using the counter electromotive force included in the voltage of the terminal made by Y connection by using the resistance of each phase without using Hall sensor or encoder generally used to detect the rotor position. A sensorless drive system for a square wave brushless direct current (DC) motor is proposed. To do this, we propose a method to detect the rotor position from the analyzed terminal voltage waveform by performing terminal voltage analysis of each phase for 3-phase, 2-exciton unipolar PWM.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.162-164
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• 1997

This paper represents comparisons between induction motor and synchronous reluctance motor(SynRM), on the basis of the obtainable torque-per-volume. The Synchronous Reluctance candidate has been individuated in a motor with segmented rotor; the rotor segments have been properly designed, to avoid rotor iron losses.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.12
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• pp.1218-1229
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• 1991

The time optimal position control design can be repeatedly taken from the initial state of a dynamic system to a desired one as fast as possible in the industrial drives. In this case, an induction machine parameters will vary due to temperature, frequency, and saturation effects. In particular, the rotor resistance changes critically with temperature and frequency. These changes affect the command values of the stator current components and slip speed. There is a mismatch between the commanded variables and actual ones of the induction motor drive, and this situation leads to coupling of the vector controller from the plant, i.e. the induction motor . Consequences of such a coupling include the initiation of oscillations of the rotor flux and unsuitable switching of electromagnetic torque for the induction motor servo drive. Therefore, this paper describes a rotor resistance parameter compensating method for the induction motor, And the validity of the proposed design method is confirmed by simulation studies and experiment results.