• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.983-985
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• 2001

Sensorless induction motor drive is much studied due to the cost and reliability of speed and position sensors. Most sensorless algorithms are based on the mathematical modeling of induction motor including electrical variables such as phase current and voltage. Therefore, the accuracy of such variables largely affects the performance of sensorless induction motor drive. However, the phase voltage does not have to be directly monitored because of switching noise, and they may be reconstructed by using the command voltage. The output voltage of SVPWM-VSI supplying the motor has a considerable error, especially in a low speed range because SVPWM-VSI has a poor resolution in a low command voltage. Such a voltage information effect in speed sensorless control of induction motor has been investigated in this paper.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.1
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• pp.7-11
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• 2014

Induction motor is the most widely used to obtain the driving force in the industrial site. Induction motor is generally applied to the constant speed operation. Induction motor generates a high current at startup. So analysis for both steady state operation and start-up transient is required. In most cases, an equivalent circuit is used for the characteristics analysis of the induction motor. In this study, the two programs are applied to analyze for the rated speed as well as entire speed range. We confirmed that calculation results of the two programs are similar to each other.

• Journal of Advanced Marine Engineering and Technology
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• v.17 no.5
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• pp.86-98
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• 1993

The application of A.C. motor for servo system is rapidly increased according to the recent advance of power electronics and digital control techniques. The induction motor which has a simple structure and needs less maintenance has become to be used widely in the industrial field for the speed and position control recently. In this paper, the full-bridge resonant inverter is applied to the speed control of single phase inducting motor. The digital PID control algorithm is used and the control parameter is determined by the Zigler-Nichols transient response method. The speed control is carried out by the one chip micro-processor(intel EV 8097BH) and control program is developed by the assembly language. By the experimental result, it is confirmed that the speed of single phase induction motor driven by full bridge series inverter can be smoothly controlled by a digital PID controller.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.879-885
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• 2000

This study is carried out to make clear the reason of occurrence of sudden acceleration incident of AT vehicle. The stepping motor is used to control the engine speed at idle by compensating the volume of air. By the way it's valve is contaminated by blow-by gas, deposit and back fire etc. This contamination could occur the load of motor at low temperature. This plays an important role in damaging the motor's coil with the motor's performance interfered. If it's coil is damaged the ISC could malfunction. If these phenomena occur, the speed of engine may increase or the engine may stall with hunting.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.4
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• pp.219-221
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• 2002

This paper presents an electric scooter development using blushless DC motor. In recent scooters was to develop for sport leisure and short transportation. Most of scooter are used petroleum gas. This gas scooter has disadvantage to pollute the air. Some of scooters have developed by DC motor which require a brush. However brushless motors have higher maximum speed and greater capacity, save maintenance labour and produce less noise. There is also greater freedom in planing the usage of brushless motors. In this paper we develop an electric scooter driving BLDC motor for design smart system and control speed of scooter with current reference signal to apply voltage to motor by means of three phase inverter. Using accelerator device we generate current reference to control speed and send the current to a MICOM by A/D converter. This MICOM produces the voltage signal and hall sensors signal and PWM controller drive three phase inverter to minimize error between the reference and an actual current.

• Design & Manufacturing
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• v.16 no.4
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• pp.40-45
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• 2022

The EV electric vehicle market is growing rapidly worldwide. An electric vehicle means a vehicle that uses energy charged through an electricity source as power. The precision of the press is important to mass-produce the drive motor, which is a key component of the electric vehicle. The size of the driving motor is increasing, and The size of the mold is also growing. In this study, the precision of large high-speed presses for mass production of driving motors was measured. A study was conducted on the measurement method of press and the analysis of measurement data. A drive motor is a component that transmits power by converting electrical energy into kinetic energy. EV driven motors have key material properties to improve efficiency. The material properties are the thickness of the material. As a method for improving performance, use a 0.2mm thin steel sheet. Mold is also becoming larger. As the mold grows, the size of the high-speed press for mass production of the driving motor is also increasing. Also, the precision of the press is the most important because it uses a thin iron plate material. So the importance of large press precision is being emphasized. In this study, the effect of large high-speed press structure on precision was verified

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.857_858
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• 2009

On account of small size and light weight, a high-speed machine is regarded as a key technology for many future applications of drive systems. In high-speed applications, permanent magnet (PM) synchronous motors have a number of merits such as high efficiency and high power density. Accordingly, they are suitable for driving the air-blower of a fuel cell electric vehicle (FCEV) where space and energy savings are critical. Particularly, a surface-mounted PM motor of them is mainly used as a high-speed machine. However, the motor has a fatal flaw owing to a retaining can to maintain the mechanical integrity of a rotor assembly. The can results in the increase of magnetic air-gap length in the surface-mounted PM motor. Thus, in this paper, an interior PM motor is designed in order to drive the air-blower of FCEV instead of the surface-mounted PM motor, and the experimental results of two models are compared to verify the capability of the interior PM motor for a high-speed machine.

• Journal of The Korean Society of Integrative Medicine
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• v.3 no.1
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• pp.1-10
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• 2015

Purpose: This study investigated the relationships of handwriting legibility and perceptual-motor skills, and handwriting speed and perceptual-motor skills. And identified the predictors that most affect the handwriting of preschool children. Methods: Twenty-three typically developing preschool aged children (mean age: 68.61 months, SD=2.04) were selected through the Korean-Denver Developmental Screening Test-2(K-DDST-2). The children were tested with regard to handwriting legibility, visual perception, visual-motor integration and fine-motor coordination. Results: First, a significant relationship was not found among handwriting legibility, visual perception, visual-motor integration and fine-motor coordination. Second, a significant relationship was found among handwriting speed, visual perception and fine-motor coordination. Third, stepwise multiple regression analyses showed that general visual perception were significant predictors for handwriting speed. Conclusion: Occupational therapists should evaluate children's visual perception levels utilizing a standardized test, and focus on general visual perception in order to improve handwriting skill(speed). Also, occupational therapists are expected to play an important role in the management and treatment of children's handwriting skills.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.8 s.185
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• pp.64-71
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• 2006

In this paper, a uniform speed controller for an ultrasonic rotary motor is developed using the phase-difference method. The phase difference method uses traveling waves to drive the ultrasonic motor. The traveling waves are obtained by adding two standing waves that have a different phase to each other. A compact phase-difference driver system is designed and integrated by combining VCO(Voltage Controlled Oscillator) and phase shifter. Theoretically the relationship between the phase difference in time and the rotational speed of the ultrasonic motor is sine function, which is verified by experiments. Then a series of experiments under various loading conditions are conducted to characterize the motor's performance that is the relationship between the speed and torque. Proportional-integral control is adopted for the uniform speed control. The proportional control unit calculates the compensating phase-difference using the rotating speed which is measured by an encoder and fed back. Integral control is used to eliminate steady-state errors. Differential control for reducing overshoot is not used since the response of ultrasonic motor is prompt due to its low inertia and friction-driving characteristics. The developed controller demonstrates reasonable performance overcoming disturbing torque and the changes in material properties due to continuous usage.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.1
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• pp.61-73
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• 1985

The induction motor is widely used in the power equipments of the ship and the various industrial drive applications because it is robust and relatively simple and cheap to manufacture, but it has a disadvantage that the speed of induction motor is not controlled in wide range such as d.c motor. In this paper, the characteristics relating to the Kramer system that the speed of three phase wound type induction motor is controlled by changing the exciting e.m.f. of the secondary circuit is described. In order to analyze the characteristics, a new simplified and approximated T-type equivalent circuit from the Kramer circuit with three phase graetz connection and d.c machine is proposed. The stator current, motor torque and mechanical output power are computed by the current, torque and power equations derived by its equivalent circuit. Through the experiments, the $I_f-N$, torque-slip and current-slip characteristic curves of the tested motor are obtained and the various needed constants are determined. The numerical values obtained from the above method are compared with experimental values under the same conditions. As a result of the above investigation, it is found that the induction motor speed by the Kramer system is controlled by 28 per cent under the rated speed by changing the field current of d.c motor and the values computed by the current and torque equations derived by the simplified and approximated T-type equivalent circuit generally come to approach the experimental values.