• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.1
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• pp.29-34
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• 2005

The wound induction motor can provide high starting torque and reduced starting current simultaneously by inserting large resistor externally when starting. And this technique is one of the well known methods among the induction motor starting methods and generally used for heavy load starting such as crane and cement factories. The conventional PI controller has been widely used in industrial application due to the simple control algorithm and is generally used for control of current torque, position, and speed for the wound induction motor drive system. However, the conventional control system for wound induction motor may result in poor performance because sensors have to be used but are often limited by the environmental condition. Recently, to overcome these problems, many sensorless vector control methods for the wound induction motor have been studied. This paper presents a MRAS method for sensorless vector control of the wound induction motor drive. In the conventional MRAS method, in low frequency, the stator resistance variation may result in poor performance. Therefore, this paper presents a MRAS method with stator and rotor resistance tuning for sensorless vector control of the wound induction motor to overcome several shortages of the conventional MRAS caused by parameter variation and to enhance the robustness of the sensorless vector control. The validity and effectiveness of the proposed method is verified through digital simulation.

• 전기의세계
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• v.24 no.2
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• pp.78-83
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• 1975

There are many studies recently, on a wound rotor induction motor operation as synchronous rotating speed, and such an induction motor is so called an induction synchronous motor. In above desciption the region of pull into-step that the wound rotor induction motor as a synchronous motor has not been calculated. This paper deals with such a region. Generally, induction synchronous motor is different from a synchronous motor in many respects. In considering these respects, characteristic equations of motion for this motor are induced adoption small signal linearization, continuous quasili-nearization and state variable grouping technique. For pulling-into-step of Induction Synchronous Motor, we first analyze these equations with digital computer and compare the former with datas calculated by motor experimentation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.704-713
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• 2002

This paper describes operational characteristics of wind turbine induction generators interconnected with distribution networks using PSCAD/EMTDC. Due to the simple and durable structure, induction generators are the most common type used in wind Power generation. Generally, induction generators are classified into two groups according to the shape of rotor, one is squirrel-cage type and the other is wound-rotor type. In this study, we simulate the start-up and the output variation of generators interconnected with distribution networks and compare the operational characteristics of squirrel -cage type and wound-rotor type induction generators located in the unfaulted distribution lines about the disturbance occurred on the associated distribution feeders emanated from the substation to which wind turbine generator is connected. In order to obtain the realistic results, we use the radial distribution network of IEEE 13-bus model.

• Journal of information and communication convergence engineering
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• v.7 no.1
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• pp.46-51
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• 2009

In this paper, the two-axis theory is adopted to analyze the secondary excited induction generator applied to random wave input generation system. The analysis by the two-axis theory helps to know the transmitted power of the induction machine. The electric variables, like as primary and secondary currents, voltages, and electric output power, were able to express as equations. These equations are help to simulate the generation system numerical model and to know the transient state of the system. As it is preferred to stabilize the output voltage and frequency in the constant level, microcomputer controlled VSI connected to the secondary windings supplies the secondary current with slip frequency. For testing the appropriateness of this method, the input torque simulator in the laboratory to drive the secondary excited results show the advantage of secondary excited induction generator system for the random input wave generation system.

• Journal of the Korean Society for Railway
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• v.4 no.1
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• pp.16-22
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• 2001

This paper describes two different systems which can compensate harmonic currents generated in the power system. As non-linear loads increase gradually in industry fields, harmonic current generated in the electric power network system also increases. Harmonic current makes a power network current distorted and generates heat, vibration, noise in the power machinery. Many approaches have been applied to compensate harmonic currents generated in the power network system. Among various approaches, in this paper, two kinds of approaches are compared and evaluated. They are flywheel compensator based on secondary excitation of wounded rotor induction motor(WRIM) and primary excitation of squirrel cage induction motor(SCIM). Both systems have a common structure. They use a flywheel as a energy storage device and use PWM inverters.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.4
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• pp.27-31
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• 1999

This paper covers starting characteristics and design of wound motor induction rmtor can used to double excited induction mootor. They are employing in many electrical equiprrent system of industrial field The stator is satre as that of conventional induction motor. But rotor was rewind with new style, as result both of starting torque and operating efficiency could be high, But starting current could be small. Could obtain the satre result as that of conventional induction rmtor with external resistance on the rotor. The structure could be simple, system cost could be low and the maintanence free, Because of no slip rings, no brushes and no external resistance.stance.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.885-887
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• 2008

본 논문에서는 전원전압 불평형시 권선형 유도전동기(wound-type induction motor)에 발생하는 토크리플을 저감하는 방법을 제안한다. 전원 전압에 불평형이 발생할 경우, 전류와 전압은 정상분과 역상분으로 표현되고 역상성분에 의해 고정자에 무효 전력리플이 발생하며 이 성분에 의해 유도전동기는 토크 맥동을 발생한다. 무효전력 리플 성분을 0으로 제어함으로써 토크 리플을 저감할 수 있다. 제안된 토크리플 저감 방법은 PSCAD/EMTDC 시뮬레이션으로 알고리즘의 타당성이 검증된다.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1995.06b
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• pp.55-75
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• 1995

Induction of HMG-Co A reductase (HMGR) is essential for the biosynthesis of sesquiterpenoid phytoalexins and steroid derivatives in Solanaceous plants following wounding and pathogen infection. To better understand this complex step in stress-responsive isoprenoid synthesis, three classes of cDNAs for HMGR (hmg1, hmg2, and hmg3) were isolated from a potato tuber library. The potato cDNAs had extensive homology in open reading frames but had low homology in the 3'-untranslated regions. RNA gel blot analysis using gene-specific probes revealed that hmg1 is induced by wounding but wound induction is strongly suppressed by arachidonic acid or by inoculation with Phytophthora infestants. In contrast, hmg2 and hmg3 are slightly induced by wounding and strongly enhanced by arachidonic acid or inoculation. The induction and suppression of HMGR genes parallel the suppression of steroid and stimulation of sesquiterpenoid accumulations observed in earlier investigations. Treatment of the tuber disks with a low concentration of methyl-jasmonate doubled the wound induced accumulation of hmg1 transcripts and steroid-glycoalkaloid accumulation, but did not affect the abundance of transcripts for hmg2 or hmg3 nor induce phytoalexins. High concentration of methyl-jasmonate suppressed hmg1 mRNA and steroid-glycoalkaloid accumulation, induced hmg3 mRNA, and did not elicit phytoalexins. Lipoxygenase inhibitors suppressed the accumulation of of hmg1 transcripts and steroid-glycoalkaloids, which were restored by exogeneous methyl-jasmonate. Methyl-jasmonate applied together with arachidonic acid enhanced the elicitor induced accumulation of sesquiterpenes and sustained steroid-glycoalkaloid levels with transcript levels for the various HMGR mRNAs equal to or greater than wound-only treatment. These results domonstrate that the consequences of wound- and pathogen-responses of plants are different at the levels of gene expression and associated secondary metabolism.

• Physical Therapy Korea
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• v.10 no.2
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• pp.61-70
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• 2003

The purposes of this study was to evaluate the effect of low power GaAsAl laser on tissue contraction in a linear incision wound on rat skin. The linear incision wound was made on the midline of the backside in the experimental animals. Low power laser applications with different intensities such as 3, 6, or 10 mW were applied to the experimental animals twice a day for 10 days. On either the seventh or tenth postoperative day, the quantitative analysis of the inflammatory reaction surrounding the linear incision wounds on the rats were performed using enzymatical analysis of myeloperoxidase (MPO) activity. The number of neutrophil was $.07-1.0{\times}106/m{\ell}$ from a normal blood sample that was obtained from the normal experimental animals. Each concentration of neutrophil showed .04-.62 unit activity of MPO. Therefore, the 6 unit activity of MPO per neutrophil was $.57{\pm}.014{\times}10^{-6}$ unit. On the 7th and 10th post operative day, non treated tissues demonstrated increased MPO activity as compared to that of normal tissue. These data indicated that the inflammatory reaction of tissue was induced after wound induction and the MPO activity were increased in the inflammed tissues. While both 3 mW or 6 mW intensity of laser treatments did not affect the tissue MPO activity, 10 mW intensity of laser treatment significantly decreased the tissue MPO activity on the 7th and 10th post operative day. These data demonstrated that only 10 mW intensity of laser treatment successfully suppressed tissue inflammatory reaction after wound induction. In conclusion, these findings suggested that 10 mW of GaAIAs laser treatments effectively suppressed the inflammatory reaction of tissue that was induced during the wound healing process.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.771-774
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• 2009

In this paper, the secondary wound type induction machiner was applied to random wave input generation system. It is necessary to know the transient sate of the induction machine, for getting the stabilized power from the random wave input. Here the two-axis theory is adopted and the primary and secondary variables like as current, voltages, power were calculated. From the fluctuating natural power, we can get the CVCF output power by using microprocessor control VSI.