• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.9
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• pp.427-433
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• 2001

A linear ultrasonic motor was designed by a combination of the first longitudinal and fourth bending mode, and the motor consisted of a straight aluminum alloys bar bonded with a piezoelectric ceramic element as a driving element. That is,$L_1-B_4$ linear ultrasonic motor can be constructed by a multi-mode vibrator of longitudinal and bending modes. Linear ultrasonic motors are based on an elliptical motion on the surface elastic body, such as bar or plates. In general, the natural resonance frequency of the stator is used as a driving frequency of the motor which provides a large elliptical motion. The corresponding eigenmode of one resonance frequency can be excited twice at the same time with a Phase shift of 90 degrees in space and time. And the rotation can be reversed by changing the phase between the two signals from sin$\omega$t to cos$\omega$t. Moreover, the tangential force pushes the slider(rotor) and, therefore, determines the thrust and speed of the motor. The experimental results of fabrication motors, bimorph-tyPe motor showed more excellent than unimorph-type. The maximum speed of TBL-200, TBL-300, TBL-400, TBL -220, TBL-310 and TBL-420 motors were 0.12, 0.37, 0.39, 0.14, 0.55 and $0.60ms6{-1}$, respectively. And the efficiency were reported 1.15, 7.9, 6.6, 2.36, 10.1 and 16.5%, respectively. That time, output thrust of the motor was a strong(1~2N) and the weight of stator was a lightness(5~7g).

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.650-654
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• 2007

Induction motors are widely used as a source of driving force in electric vehicles and pulse width modulation (PWM) inverters are applied to their operation. The issue is that insulation of inverter-fed induction motors (IFMs) are more stressed than in line-powered motors by transient voltages. This paper dealt with experimental results on transient voltage produced by the PWM operation of an induction motor. The peak and the dv/dt of transient voltage depending on the length of power feeding cable and operating frequency were investigated. In the experiment, transient voltages up to 3.3PU of the rated-inverter voltage were recorded for the cable length of 50m. As the cable length is increased, the peak voltage appeared at the motor terminals increases. This phenomenon can be explained by the reflection and the transmission of travelling wave. Consequently, special care for the cable length between the motor and the inverter should be taken in the use of IFM to ensure the full life of insulation system.

• Elastomers and Composites
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• v.46 no.4
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• pp.311-317
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• 2011

The neodymium magnet inserted mold was proposed to orient magneto-responsible particles efficiently. The anisotropic magneto-rheological elastomer(MRE) was prepared using the new mold and the optimum amounts of the particles was 30 vol.%. As the orientation of particles was increased, the tensile strength of MRE was decreased, while the hardness of MRE was increased. It was found that the MRE containing 30 vol.% of magneto-responsible particles showed the maximum magneto-rheological effect. The ratio of shear modulus shift was 59% at the input current of 3 A. The transmissibility of MRE was decreased with increasing the input current and loading amounts of magneto-responsible particles. Therefore, the damping property of MRE could be improved by preparing the anisotropic MRE.

• International Journal of Control, Automation, and Systems
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• v.4 no.4
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• pp.414-427
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• 2006

This paper presents an adaptive feedback linearization control scheme for induction motors with simultaneous variation of rotor and stator resistances. Two typical modeling techniques, rotor flux model and stator flux model, have been developed and successfully applied to the controller design and adaptive observer design, respectively. By using stator fluxes as states, over-parametrization in adaptive control can be prevented and control strategy can be developed without the need of nonlinear transformation. It also decrease the relative degree for the flux modulus by one, thereby, yielding, a simple control algorithm. However, when this method is used for flux observer, it cannot guarantee the convergence of flux. Similarly, the rotor flux model may be appropriate for observers, but it is not so for adaptive controllers. In addition, if these two existing methods are merged into overall adaptive control system, it brings about structural complexies. In this paper, we did not use these two modeling methods, and opted for the airgap flux model which takes on only the positive aspects of the existing rotor flux model and stator flux model and prevents structural complexity from occuring. Through theoretical analysis by using Lyapunov's direct method, simulations, and actual experiments, it is shown that stator and rotor resistances converge to their actual values, flux is well estimated, and torque and flux are controlled independently with the measurements of rotor speed, stator currents, and stator voltages. These results were achieved under the persistent excitation condition, which is shown to hold in the simulation.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.9
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• pp.1146-1149
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• 2014

To discriminate polarities of stator windings for 3 phase induction motors terminal tags of which are not readable, it is possible to utilize the residual magnetic flux present at their rotors as well as to use the way based on external exciting current. The induced voltages are basically decided by parameters such as the quantity of residual flux, the rotator speed by hand force and the phase properties between stator windings. To adopt induced voltages by residual flux for polarity discrimination at sites, the measured voltages by multi-testers need to be readable in magnitude enough to discriminate winding condition with reasonable phase characteristics. This study focuses on the analysis of various connection cases in the expectation that the summing voltages induced by residual flux shall show zero in case of normal connections while the sum becomes greater indication if the connection is in wrong condition. The proposed method is applied to actual motors to disclose how effective it is for polarity discrimination at sites through comparison of output signals between normal and fault connections.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.172-178
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• 2012

Packaged power systems are very convenient for transferring and installing, and can supply electric power steadily for the areas which have a great difficulty in drawing power line from the outside. Then, the equipments have been widely used in such mountain areas and the back of beyond. Generally, compressed air has been employed to start the dynamo-engines for P.P.S. However, these systems necessitate air compressors, air tanks, air starting motors and pipe lines for transferring compressed air etc. Recently, starting systems which have only batteries and series DC motors as whole automobiles have been applied due to their simplicity and economy. In this paper, developed new starting motor for the P.P.S. And we achieved the better results from performance tests.: Output power, torque and speed.

• Journal of IKEEE
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• v.15 no.3
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• pp.227-234
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• 2011

The Interest in robotics has been steadily increasing in recent times both in Korea as well as abroad. Research on robots for new and diverse fields is ongoing. This study discusses the current research and development on robot actuator, which are used to control the joints of robots, and focuses on developing more efficient technology for joint control, as compared with the current technologies. It also aims to find means to apply the abovementioned technology to diverse industrial fields. We found that easy and effective control of actuators could be achieved by using ZigBee sensor networks, which were widely being used on wireless communications. Throughout the experiments it is proved that the developed wireless actuator could be used for easy control of various robot joints. This technology can be effectively applied to develop two-legged robots that will be able to walk like human, or even quadruped and hexapod robots. It can also be applied to motors used in industry. In this study, we develop an extremely minimized ZigBee sensor network module that can be used to control various servo motors with low power consumption even if it is long distances. We realized effective wireless control by optimizing the ZigBee antenna, and were able to quickly check the status of relevant Tree node through mutual communication between the servo motors composing the ZigBee sensor network and the main server control modules. The developed Servo Motor with ZigBee sensor network modules can be applied in both robotics as well as for home or factory automation.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.8
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• pp.1195-1202
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• 2010

When modelling lots of induction motors to design and configure an engine room simulator, the 2 parameters equivalent circuit has many practical benefits as it reduces working hours considerably without requiring complicated technical data from makers except the ratings of motors. The basic properties such as torque and load current are shown well matched with real cases by this method, but almost the only drawback of 2 parameters circuit is that it reveals inherently higher power factor in the whole operation range due to disregarding the exciting current of the induction motor to maximize the simplification. This paper suggests a modelling module as a practical tool to compensate the power factor by inserting a virtual compensation current into the load current from 2 parameters equivalent circuit, and the simulated results show satisfactory outputs and the improved power factor indication by performance curves when compared to the cases of 2 parameters-equivalent circuit.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.1-8
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• 2017

This paper presents the development of an adaptive cruise control (ACC) system, which is one of the typical advanced driver assist systems, for 4-wheel drive hybrid in-wheel electric vehicles. The front wheels of the vehicle are driven by a combustion engine, while its rear wheels are driven by in-wheel motors. This paper proposes an adaptive cruise control system which takes advantage of the unique driveline configuration presented herein, while the proposed power distribution algorithm guarantees its tracking performance and fuel efficiency at the same time. With the proposed algorithm, the vehicle is driven only by the engine in normal situations, while the in-wheel motors are used to distribute the power to the rear wheels if the tracking performance decreases. This paper also presents the modeling of the in-wheel motors, hybrid in-wheel driveline, and integrated ACC control system based on a commercial high-precision vehicle dynamics model. The simulation results obtained with the model are presented to confirm the performance of the proposed algorithm.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1042-1048
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• 2012

A 2-axis gimbal system is one of main disturbance sources affecting image jitter response of a satellite. The gimbal system comprises azimuth stage and elevation stage, and these pointing mechanism can be rotated by stepping motors about its azimuth and elevation axes simultaneously. Because of the complex and coupled dynamic motion of the gimbal system, its moment of inertia and structural modes can be changed according to the system configuration, and thus the gimbal system generates complicated and non-linear disturbance characteristics. In order to improve the jitter response of a spacecraft, it is an indispensable process to reduce the micro-vibration disturbance level of the antenna system. In the present research, a 2-axis gimbal system was manufactured and then its micro-vibration test was performed in terms of two types of stepping motors(2-phase and 5-phase). The test results show that the disturbance level of the gimbal system can be reduced by replacing the 2-phase stepping motor with the 5-phase one, and the average disturbance attenuation ratio is 56 % in peak level and 48 % in standard deviation level. The experimental results confirm that it is an efficient jitter reduction method to adopt a high-phase stepping motor.