• Journal of Power Electronics
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• v.17 no.5
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• pp.1203-1210
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• 2017

This paper presents an improved switching selection method for the direct torque control (DTC) of five-phase induction motors (IMs). The proposed method is conducted using optimal switching selection. A five-phase inverter has 32 voltage vectors which are divided into 30 nonzero voltage vectors and two zero voltage vectors. The magnitudes of the voltage vectors consist of large, medium, and small voltage vectors. In addition, these vectors are related to the torque response and torque ripple. When a large voltage vector is selected in a drive system, the torque response time decreases with an increased torque ripple. On the other hand, when a small voltage vector is selected, the torque response time and torque ripple increase. As a result, this paper proposes an optimal voltage vector selection method for improved DTC of a five-phase induction machine depending on the situation. Simulation and experimental results verify the effectiveness of the proposed control algorithm.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.10
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• pp.1066-1074
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• 1990

In this paper, we attempt to control induction motors with high power efficiency as well as high dynamic performance by utilizing the recently developed theories : singular perturbation technique and noninteracting feedback control. Our controller consists of three subcontrollers` a saturation current controller, a decoupling controller, and a well-known flux simulator. The decoupling controller decouples rotor speed (or motor torque) and rotor flux linearly. Our controller does not need the rotor resistance that varies widely with the machine temperature. To illuminate the practical significance of our results, we present simulation and experimental results as well as mathematical performance analysis.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.608-616
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• 2006

Recently, a switched reluctance motor is widely used in various industries because it has many advantages such as a simple structure, robustness, less maintenance, high torque/weight ratio, and easy speed control over other types of motors. However, a switched reluctance motor inherently produces acoustic noise and vibration caused by torque ripple. Applications of these motors where silent operation is desirable have thus been limited. In this paper, a new stator pole face having a non-uniform air-gap and a pole shoe attached to the lateral face of the rotor pole are suggested in order to minimize torque ripple. The effects of each design parameter are validated using a time-stepping finite element method. The parameters are optimized by utilizing response surface method (RSM) combined with (1+1) evolution strategy. The result shows that the optimized shape gives higher average torque and drastically reduced torque ripple.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.2
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• pp.49-55
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• 1999

This paper proposes an efficient 2D Finite Element Method(FEM) taking into account the end-ring of three phase squirrel-cage induction motors. The parameters of the squirrel-cage induction motor such as conductivity of secondary conductor have an effect on the characteristics of a motor. Especially, if the characteristic analysis is done without considering the end-ring, the good results can not be obtained. Therefore, we calculated a new resistivity of the secondary conductor including the end-ring's resistance to apply the 2D FEM. Then, the performances of the motors are analyzed by using the new resistivity of secondary conductor which contains the end-ring resistivity. The validity of the proposed method is verified by comparing the numerical results with experimental ones.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.6
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• pp.484-489
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• 2003

In this paper, a single phase driven piezoelectric motor design was presented for linear motion Two metal/ceramic composite actuators, a piezoelectric ring which was bonded to a metal endcap from one side, were used as the active elements of this motor. The motor was composed of a piezoelectric ceramic, a metal ring which has 4 arms, and a guider. Motors with 30 [mm] and 35 [mm] diameter were studied by finite element analysis and experiments. As results, the maximum speed of motor was obtained at resonance frequency. When the applied voltage of the motor increased, the speed was increased. Also, bidirectional motion of the motor was achieved by combining two motors which have different resonance frequency. But the characteristics of bidirectional motion were not equaled, because of the problem of reproduction on the fabrication and the experiment. If present motor is used at the auto-zoom device of a camera, it will have much advantage. Because the direct linear motion can be achieved with a simple structure of motor and no gearbox of total system.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.334-340
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• 2002

This paper proposes a new anti-slip re-adhesion control system fur electric railway vehicle driven by inverter-fed induction motors. This paper introduces an instantaneous tangential farce coefficient estimator between driving wheel and rail, which is based on disturbance observer. The torque command of proposed system regulates to exceed this estimated tangential farce coefficient in order to avoid undesirable slip phenomenon of driving wheels. We have already proposed the anti-slip re-adhesion control system based on disturbance observer for simplified one wheel equivalent model successfully. This paper extend to this system to the actual bogie system, which has four driving wheels driven by two induction motors fed by one inverter. In order to apply anti-slip re-adhesion control to the actual bogie system a new anti-slip re-adhesion control based on both disturbance observer and speed sensor-less vector control of induction motor with quick response are combined. The experimental results and the numerical simulation results prove the validity of the proposed control system.

• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.90-92
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• 2002

This paper presents an improved C-Dump converter system for switched reluctance motors(SRM). The proposed C-Dump converter derived from the conventional converter for SRM. The proposed converter could overcome the limitation of the conventional C-Dump converter, and could reduce the whole cost of the SRM system since the voltage stress of the dump switch $T_d$ is reduced to $V_{dc}$ when compared with $2V_{dc}$ for the conventional C-Dump converter. The attractive features of the proposed converters are; high-efficient and low-cost, elimination of dump inductor, simple control strategy, smaller size arid light weight. The proposed converter is able to be fast magnetization by $2V_{dc}$, which is sum of the input voltage and charging voltage of the dump capacitor. Also, this topology has many advantages such as freewheeling of phase winding without complex control, reduction of current ripple, reduction of torque ripple, and reduction of switching frequency. Simulation demonstrates the good performance of the converter.

• Journal of Biosystems Engineering
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• v.30 no.3 s.110
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• pp.179-184
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• 2005

The purpose of this study was the development of teat-cup attachment module for robot milking system. The teat-cups attachment module was controlled on the two dimensional space independently, Each teat cup of an end effector was independently controlled via two axis control based on the position information data obtained from the image processing system. This system was developed install of all 4 teat cups at the same time after adjusting positions of each teat sequentially. The individual motion system was operated using two servo motors for the high speed of teat position adjustment. The errors fur the individual motion system of teat cups were maximum 1.0mm, minimum 0.0mm, and average 0.6mm. The operating time for adjusting the teat cups position required about 1.0 second. It is envisaged that teat cups attachment module can be applicate to milking robot being developed in consideration of the experiment results for the teat cups operation accuracy and the actuation speed of servo motors.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.203-209
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• 2014

The rear center-hinge bracket is designed for supporting and folding the rear-seat backrest. This bracket needs to be strong enough to be able to rigidly hold the rear-seat backrest and to withstand luggage loads from the car trunk that are generated when a vehicle is driving on the roads. Particularly, current accident studies report that many serious occupant injuries occurred when the rear-seat back easily folded inward toward the car interior, driven by the luggage loads in the trunk. Given this fact, the robust design of the rear center-hinge bracket that mainly supports the rear backrest has become more important for providing customer safety and preventing high warranty and durability problems. However, none of the studies have emphasized its significant role and considered its robust optimization. Therefore, this paper presents how the hinge-bracket design is optimized based on an application of the finite-element method coupled with the parameter design using Taguchi's design experiment. Finally, Taguchi method's application optimizes a robust center-hinge bracket that shows more rigid performance although it has lighter weight and thinner thickness.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.2 s.179
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• pp.43-50
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• 2006

Recently, with rapid development of semiconductor and flat panel display, the manufacturing equipments are required to have large travel range, high productivity, and high accuracy. In this paper, an ultra precision decoupled dual servo (DDS) system is proposed to meet these requirements. And a control scheme for the DDS is studied. The proposed DDS consists of a $XY{\Theta}$ fine stage for handling work-pieces precisely and a XY coarse stage for large travel range. The fine stage consists of four voice coil motors (VCM) and air bearing guides. The coarse stage consists of linear motors and air bearing guides. The DDS is mechanically decoupled between coarse stage and fine stage. Therefore, both stages must be controlled independently and the performance of the DDS is mainly determined by the fine stage. For high performance tracking, the controller of fine stage consists of time delay control (TDC) and perturbation observer while the controller of coarse stage is TDC alone. With these individual controllers, two kinds of dual-servo control strategies are suggested: master-slave type and parallel type. By simulations and experiments, the performances of two dual-servo control strategies are compared.