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Improved Deadbeat Current Controller with a Repetitive-Control-Based Observer for PWM Rectifiers

  • Gao, Jilei;Zheng, Trillion Q.;Lin, Fei
    • Journal of Power Electronics
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    • 제11권1호
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    • pp.64-73
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    • 2011
  • The stability of PWM rectifiers with a deadbeat current controller is seriously influenced by computation time delays and low-pass filters inserted into the current-sampling circuit. Predictive current control is often adopted to solve this problem. However, grid current predictive precision is affected by many factors such as grid voltage estimated errors, plant model mismatches, dead time and so on. In addition, the predictive current error aggravates the grid current distortion. To improve the grid current predictive precision, an improved deadbeat current controller with a repetitive-control-based observer to predict the grid current is proposed in this paper. The design principle of the proposed observer is given and its stability is discussed. The predictive performance of the observer is also analyzed in the frequency domain. It is shown that the grid predictive error can be decreased with the proposed method in the related bode diagrams. Experimental results show that the proposed method can minimize the current predictive error, improve the current loop robustness and reduce the grid current THD of PWM rectifiers.

실시간 공정신호를 통한 용접공정 알고리즘에 관한 연구 (A Study on Welding Process Algorithm through Real-time Current Waveform Analysis)

  • 윤진영;이영민;신순철;최해운
    • Journal of Welding and Joining
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    • 제33권4호
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    • pp.24-29
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    • 2015
  • The current waveform was analysed to monitor the weld quality in real time process. The acquired current waveform was discretely analysed for the top and bottom limits of peaks as well as the pulse frequency measurement. Fast Fourier Transform was implemented in the program to monitor the pulse frequency in real time. The developed algorithm or program was tested for the validation purpose. The cross-section of weld profile was compared to the current waveform profile to correlate the monitored signal and the actual parts. Pulse frequency was also used as auxiliary tool for the quality monitoring. Based on the results, it was possible to evaluate the quality of welding by measure the current waveform profile and frequency measurement.

전류모드제어를 위한 연속시간모델의 새로운 유도 방법 (Alternative Derivation of Continuous-Time Model for Current-Mode Control)

  • 정동열;홍성수;최병조;안현식;사공석진
    • 전력전자학회논문지
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    • 제8권2호
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    • pp.137-142
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    • 2003
  • 전류모드제어의 널리 알려진 두가지 연속시간모델이 소신호 예측에서 현저한 차이점을 보인다 따라서, 소신호에서의 불일치의 원인을 명백하게 하려고 한다. 본 논문에서는 전류모드제어를 위한 연속시간모델을 유도하는 다른 방안을 제시한다. 본 논문에서 제안한 전류모드제어모델과 기존의 전류모드제어모델과 모델링 방법의 차이점을 제시하고, 제안된 연속시간모델에 대한 타당성을 검증하기 위해 하드웨어실험과 PWM 블록의 모델에 샘플링효과를 포함하는 알고리즘을 제안하고, 전류루프이득을 시뮬레이션과 하드웨어 실험 결과와 비교, 검토하였다.

고온 초전도 한류퓨즈의 전압별 동작특성 (Operating characteristics of high Tc superconducting current limiting fuse at various voltages)

  • 최효상;현옥배;김혜림;황시돌;박권배
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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    • pp.161-163
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    • 2001
  • We present the basic properties of a superconducting current limiting fuse (SCLF) based on YBCO/Au films. The SCLFs consists of YBCO stripes covered with Au layers for current shunt. Under the source voltage of 100 $V_{rms}$, the longer the duration time of fault current was, the shorter its discharge time was. The duration time of fault current and its discharge time were reduced by increased voltages in the range of 200 - 300 $V_{rms}$. We thought that this was because the quench propagation was limited by local melting generated with higher voltage.

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아크지속시간 측정을 통한 나선형 VI 전극의 전극배치에 따른 아크제어 성능비교 (Comparison of Arc Control Ability as a Function of Configuration of Spiral Type VI Contacts by Measuring Arcing Time)

  • 김병철;박홍태;오일성;임기조
    • 한국전기전자재료학회논문지
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    • 제22권2호
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    • pp.184-190
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    • 2009
  • One of the purposes of arc control is to change its state to the diffuse state before current zero as soon as possible. This can provide optimal conditions for full extinction of arc by minimizing the quantity of residual plasma between contacts near current zero. TRV(transient recovery voltage) occurs at current zero at the same time with current interruption. If there is substantial residual plasma near current zero it can cause 'post arc current' by the interaction of its conductance with TRV. In this paper, arc control ability as a function of configuration of spiral type VI contacts was compared on the criteria of the time taken for arc to reach to the diffuse state.

전자교반을 이용한 A356 합금의 결정립제어 (The grain size control of A356 alloy by electromagnetic stirring)

  • 배정운;강충길
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2006년도 춘계학술대회 논문집
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    • pp.247-248
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    • 2006
  • In this study, the morphology of the change of primary Al phase in A356 alloy by two kinds of electromagnetic stirrers(vertical and horizontal) were investigated to obtain the globular structure. The effects of the stirring current, the stirring time and the pouring temperature were determined. The greater stirring current and longer stirring time were to get the finer the Al phase. However, over a certain stirring current and stirring time, the primary Al was merged together and was increased. The reason is the degree of breakdown of initial dendrites has been decreased by the collision and coalescence of particles with increasing stirring current and stirring time. The optimum conditions and difference of the two kinds of electromagnetic stirrers have been investigated for rheology forming with controlled solid fraction.

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평균전류모드제어의 전류응답예측을 위한 새로운 이산시간 소신호 모델 (New Discrete-time Small Signal Model of Average Current Mode Control for Current Response Prediction)

  • 정영석
    • 전력전자학회논문지
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    • 제10권3호
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    • pp.219-225
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    • 2005
  • 본 논문에서는 평균전류모드제어를 이용하는 컨버터의 전류응답을 예측할 수 있는 새로운 이산시간 소신호 모델을 구한다. 평균전류모드제어는 최대전류모드제어와 달리 전류제어를 위해 복잡한 보상기 회로를 사용하므로 컨버터의 동작 특성 해석이 어렵다. 평균전류모드제어를 사용하는 컨버터의 소신호 전류응답을 예측하기 위해 샘플러모델을 제안하고, 이 모델로부터 새로운 이산시간 소신호 모델을 구한다. 제안된 방식은 기존 방식과 달리 복잡한 형태의 보상기를 사용하는 컨버터에도 적용 가능하다. 제안한 새로운 이산시간 소신호 모델을 이용한 예측 결과를 스위칭 모델 시뮬레이션 프로그램인 PSIM을 이용한 시뮬레이션 결과 및 실험결과와 비교하여 제안한 새로운 이산시간 소신호 모델의 우수성을 보인다.

전압증가 시 재폐로 동작에 따른 변압기형 초전도 한류기의 특성 분석 (Characteristics on the Transformer-Type SFCL According to Reclosing Operation the Voltage Increase)

  • 최수근;최효상
    • 전기학회논문지P
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    • 제59권4호
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    • pp.477-480
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    • 2010
  • Fault current in power system is expected to increase by demand of power capacity. Therefore, when the fault occurred, fault current was increased in the power system. Many studies have been progressed to limit the fault current. Superconducting fault current limiter (SFCL) is one of them which has been studied in worldwide. In this paper, we will analyze characteristics of a transformer-type SFCL by reclosing operation when the voltage increases. Twice opening times in the reclosing of circuit breaker were set as the 0.5 and 15 seconds, respectively. Turn's number of primary and secondary coils set 4:2 and we increased voltages from 120V to 280V for each experiment. By the current waveform, maximum fault current in second and third cycles was lowered when the voltage was increased. In the recovery waveform, recovery time was increased as the voltage was increased. The reason was that power burden of the SFCL increased when consumption power was increased, so the time to get back to SFCL took longer. We compared the characteristics of a resistive-type and transformer-type SFCL. As a result, we found that the fault current of a transformer-type was lower than resistive-type and recovery time of the SFCL was shorter. Consequently, transformer-type SFCL was more profitable for limitation of fault current and recovery time under the same condition for reclosing operation.

Time-Delay Effects on DC Characteristics of Peak Current Controlled Power LED Drivers

  • Kim, Marn-Go;Jung, Young-Seok
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2011년도 전력전자학술대회
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    • pp.481-482
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    • 2011
  • New discrete time domain models for the peak current controlled (PCC) power LED drivers in continuous conduction mode include for the first time the effects of time delay in the pulse-width-modulator. Realistic amounts of time delay are found to have significant effects on the average output LED current and on the critical inductor value at the boundary between two conduction modes. Especially, the time delay can provide an accurate LED current for the PCC buck converter with a wide input voltage. The models can also predict the critical inductor values at the mode boundary as functions of the input voltage and the time delay.

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

  • 김우현;박철우;임성운;권우현
    • 제어로봇시스템학회논문지
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    • 제6권5호
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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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