• Title, Summary, Keyword: Time constant

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A robust indirect vector control for the rotor time constant variation of induction motors (유도전동기 회전자 시정수 변동에 강인한 간접 벡터제어)

  • 강현수;조순봉;현동석
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.45 no.3
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    • pp.365-373
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    • 1996
  • This paper presents the effects of rotor time constant variation and the on-line tuning algorithm of the rotor time constant. If the value of the rotor time constant is set incorrectly, the IFOC (Indirect Field Oriented Control)scheme exhibits deteriorated performance according to the wrong slip command. These variation effects of the rotor time constant are caused by the slip calculator where it is known that the rotor time constant play an important role in the aligned rotor flux. Using the two torque angles (stationary torque angle, rotating torque angle), the variation of the rotor time constant is identified, and the rotor time constant of the controller is tuned to the proper value of the machine. As the result, with the proposed algorithm, the dynamics of the deteriorated IFOC system, where the rotor time constant is varied, is improved. For the purpose of the validity of this proposed algorithm, the computer simulations and the experiments have been performed and the explanation of the results is presented. (author). refs., figs., tab.

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A Study on the Real Time Digital Field Time-Constant Regulator for Micro-Synchronous Machine (축소형 동기발전기 실시간 디지털 계자시정수 보상장치에 관한 연구)

  • Kim, Dong-Joon;Moon, Young-Hwan;Hwang, Chi-U
    • Proceedings of the KIEE Conference
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    • pp.253-256
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    • 1997
  • This paper describes a novel design method for compensating field time-constant of micro-synchronous machine so that its terminal flux can show the same characteristics as large-scale synchronous machine's. In addition to it, the suggested design method can determine the field time-constant regulator's parameters considered the nonlinearities of micro-synchronous machine such as saturation and loading effect. This method applied to 5kVA micro-synchronous machine, and the digital time-constant regulator with digital AVR were designed such that the short field time-constant, $T_{do}'=1.12\;sec$, can take on the large-scale synchronous machine time constant, $T_{do}'=1.47\;sec$. After determining the parameters of controllers, the real time digital time-constant regulator and digital AVR algorithm were implemented by using the PC with Penumum processor, and the usefulness of suggested real time digital time-constant regulator was verified by observing its good performance on the excitation of micro-synchronous machine.

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Characteristics variation of thermal time constant of thermocouples by the structure changes (열전대 구조변화에 의한 열시정수 특성 변화)

  • Gam, Kee-Sool
    • Journal of Sensor Science and Technology
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    • v.18 no.2
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    • pp.103-109
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    • 2009
  • Thermal time constant measurement system was designed and fabricated to measure the thermal time constant, which shows a dynamic property of the thermocouple. Type K thermocouple samples were fabricated with variable shape each other and the thermal time constants of thermocouples were measured using the home-made thermal time constant measurement system. Thermal time constants of 12 type K thermocouple samples were distributed from 0.03 s to 8.2 s. It showed experimentally that the thermal time constant of thermocouple was increased linearly for the increase of the sheath diameter of thermocouple.

Rotor Time Constant Compensation of Vector Controlled Induction Motor Using Stator Current and Flux Error (고정자 전류와 자속의 오차를 이용한 벡터제어 유도전동기의 회전자 시정수 보상)

  • 김우현;박철우;임성운;권우현
    • Journal of Institute of Control, Robotics and Systems
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    • v.6 no.5
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    • pp.367-375
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    • 2000
  • It is proposed that the rotor time constant and inductance are compensated at the same time in the indirect vector control method of an induction motor. The proposed scheme compensates the rotor time constant using the difference between the Q-axis real stator current and estimated current that is calculated from the terminal voltage and current, and compensates inductance by using the difference between the D-axis real stator flux and estimated stator flux in the synchronous rotating reference frame. Although the rotor time constant and inductance vary at once, the proposed method compensates the rotor time constant and inductance with accuracy. In addition to, two variables can be compensated not only at the steady state condition, but also at the transient state, where the torque varies in a rectangular pulse waveform. Therefore, the performance of vector control is greatly improved as verified by experiment.

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Constant-level luffing and time optimal control of a JIB crane (JIB크레인의 Constant-level luffing과 시간최적제어)

  • 최경배;홍금식;이만형
    • 제어로봇시스템학회:학술대회논문집
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    • pp.1788-1791
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    • 1997
  • In this paper constant-level luffing and time optimal control of a JIB crane is investigated. The crane is assumed to have only the derricking motion. the analysis of plance kinematics provides the relationship between the boom angle and the main hosit motor angle for constant-level luffing. The dynamic equations for the crane are very nonlimear, and therefore they are linearized for the application of the linear control theory. The time optimal control in the perspective of no-sway at the end of boom stroke is investigated.

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Simple analysis on induction motor dynamic performances by time constant parameter (유도전동기의 동특성해석에 있어서의 Time constant parameter에 의한 간이해석법)

  • 황영문
    • 전기의세계
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    • v.31 no.2
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    • pp.126-131
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    • 1982
  • Induction motors are known to cause voltage dip, oscillating torque and inrush current on the dynamic period. To compensate for these undesirable effects, the prediction of dynamic performances is required. The dynamic performances are determinated by circuit time constants. From this point of view, in this paper, the dynamic equivalent circuit included only three time-constant parameters are presented. To predict more simply dynamic performances, the new characteristics time constant parameters are analyzed, and now these parameters are described as the function of circuit time constants. This paper reviews and analyzes the use of series capacitance compensations, and the use of this analysis can make simply a prediction about oscillating conditions.

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Compensation of the rotor time constant of induction motor using current error feedback (전류오차 궤환을 이용한 유도전동기 회전자 시정수 보상)

  • 김승민;이무영;권우현
    • 제어로봇시스템학회:학술대회논문집
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    • pp.195-198
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    • 1997
  • This paper proposes the effective compensation method of the rotor time constant of induction motor. An indirect vector control method is highly dependent on the motor parameters. To solve the problem of performance degradation due to parameter variation in an indirect vector control of induction motor, we compensate the rotor time constant by current error feedback. The proposed method is a simple on-line rotor time constant compensation method using the information from terminal voltages and currents. As the current error, difference between current command and estimated current, approaches to zero, the value of rotor time constant in an indirect vector controller follows the real value of induction motor. This scheme is valid transient region as well as steady state region regardless of low or high speed. This method is verified by computer simulation. For this, we constructed the simulation model of induction motor, indirect vector controller and current regulated PWM (CRPWM) voltage source inverter (VSI) using SIMULINK in MATLAB.

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Time Constant Estimation of Induction Motor rotor using MRAS Fuzzy Control (MRAS 퍼지제어를 이용한 유도전동기 회전자의 시정수 추정)

  • Lee Jung-Chul;Lee Hong-Gyun;Chung Dong-Hwa;Cha Young-Doo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.2
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    • pp.155-161
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    • 2005
  • This paper presents time a constant estimation of induction motor using MRAS(model reference adaptive system) fuzzy control. The rotor time constant is enabled from the estimation of rotor flux, which has two methods. One is to estimate it based on the stator current and the other is to integrate motor terminal voltage. If the parameters are correct, these two methods must yield the same results. But, for the case where the rotor time constant is over or under estimated, the two rotor nut estimation have different angles. Furthermore their angular positions are related to the polarity of rotor time constant estimation error. Based on these observation, this paper develops a rotor time constant update algorithm using fuzzy control. This paper shows the theoretical analysis as well as the simulation results to verify the effectiveness of the new method.

Simulated Distribution Characteristics of Surface Temperature on Irradiating of a Laser

  • Lee, Young-Wook;Yeon, Sang-Ho
    • International Journal of Contents
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    • v.5 no.2
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    • pp.16-19
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    • 2009
  • In this paper, we concern about the distribution characteristics of surface temperature by the increment of time, diffusivity and heat flux on irradiating of a laser. The penetration depth corresponding to the induced constant heat flux or irradiated laser, is simulated by a computer algorithm. The distribution of temperature versus penetration depth for the variation of time and diffusivity is characterized at the constant heat flux and on irradiating of a laser. The temperature of constant heat flux at the fixed diffusivity or time, is decreased by the pattern of exponential function as the time t or diffusivity a is increased (a=10, 100, 1000). The temperature of constant heat flux is not changed but exponentially fixed with the increasing diffusivity and the fixed time. On the other hand, the temperature of laser at the fixed diffusivity or time is decreased linearly. Our results show that the characteristics of the simulated surface temperature in a semi-infinite solid are similar to the graphs on theoretical consideration.

Compensation of the Rotor Time Constant using Fuzzy Controller in Induction Motor Vector Control (유도전동기 벡터제어에서 퍼지제어기에 의한 시정수 보상)

  • Cha Duck-Gun;Park Jae-Sung;Park Gun-Tae
    • Proceedings of the KIPE Conference
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    • pp.21-24
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    • 2002
  • The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

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