• 제목/요약/키워드: Impedance Parameter

검색결과 283건 처리시간 0.022초

G-parameter를 이용한 직류 마이크로그리드의 컨버터 상호 안정도 분석 및 가상 임피던스를 이용한 안정도 향상 (Stability Analysis Using G-Parameters of Converters Constituting DC Microgrid and Stability Enhancement Through Virtual Impedance)

  • 이재석;이기영;김래영
    • 전력전자학회논문지
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    • 제23권5호
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    • pp.321-327
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    • 2018
  • DC microgrid system composed of multiple converters has a tendency to make the system unstable due to the interaction of converters. To solve this problem, in this paper, the interaction between cascaded converters with LC input filter is analyzed with impedance modeling using g-parameter. The input impedance and the output impedance of the system can be obtained through this technique. The stability of the system can be determined by applying Middlebrook's stability criterion to the impedance. Virtual impedance is added to the controller to enhance stability. The validity of the analysis is verified by the result of several simulations and experiments.

매설지선의 임펄스임피던스의 해석 (Analysis for the impulsive impedance of counterpoise)

  • 조정현;김종호;백영환;김동성;이강수;김기복;이복희
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2009년도 춘계학술대회 논문집
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    • pp.88-91
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    • 2009
  • For lightning currents, a grounding system shows the transient grounding impedance characteristics. A grounding system for protection against lightning should be evaluated by the transient grounding impedance, not it's ground resistance. The transient grounding impedance varies with the shape of ground electrode and earth characteristics as well as the waveform of lightning surge current. For the analysis and practical use of transient grounding impedance, the characteristics of transient grounding impedance should be analyzed theoretically and this paper suggests the theoretical analysis for the transient grounding impedance of counterpoise by using the distributed parameter circuit model. EMTP and Matlab are used to simulate the distributed parameter circuit model of counterpoise and the adequacy of the distributed parameter model of counterpoise is examined by comparing the simulated results with the measured results.

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조작자 근육 활성도 기반 양팔 로봇의 임피던스 제어 파라미터 갱신 방법 (Impedance Parameter Update Method for Dual-arm Manipulator based on Operator's Muscle Activation)

  • 백찬렬;차광열;김준식;최영진
    • 로봇학회논문지
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    • 제17권3호
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    • pp.347-352
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    • 2022
  • The paper presents how to update impedance control parameters for dual-arm manipulators using EMG signals and motions of the operator. Since the hand motions of the dual-arm are modeled to be the mass-spring-damper system in this paper, the impedance parameter update method is an important issue to reflect the operator's force. However, task space inertia to be used as the mass parameter goes to infinity if the manipulator approaches a kinematic singularity. To alleviate this issue, the impedance (stiffness and damping) parameters are divided with a diagonal element of the task space inertia. Also, the stiffness and damping matrices are updated using the normalized EMG signals captured from the operator's forearm. Through this process, the motion of the dual-arm manipulator is more stabilized even though it approaches the kinematic singularity.

분포정수회로모델을 이용한 수직 접지전극의 접지임피던스의 분석 (Analysis for the Grounding Impedance of Vertical Grounding Electrodes using the Distributed Parameter Circuit Model)

  • 이복희;김종호;최종혁
    • 전기학회논문지
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    • 제59권6호
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    • pp.1103-1108
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    • 2010
  • A grounding electrode has the transient grounding impedance characteristics against lightning surges. So the performance of grounding electrodes should be evaluated as a grounding impedance as well as the ground resistance. The frequency-dependent grounding impedance is varied with the shape and size of grounding electrode and is divided into both inductive and capacitive behaviors. This paper presents a theoretical analysis for the grounding impedance determined by the size of grounding electrode using the distributed parameter circuit model. EMTP and Matlab programs were used in calculating the frequency-dependent grounding impedances of vertical grounding electrodes. It was found that the frequency-dependent grounding characteristics of vertical grounding electrodes are characterized by the distributed parameters which are changed in the dimension of grounding electrodes.

S-파라미터 변환을 통한 비대칭 분배되는 임피던스 변환기 (An Impedance Transformer with Unequal Split Based on S-Parameter Conversion)

  • 김영
    • 한국항행학회논문지
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    • 제20권4호
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    • pp.361-366
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    • 2016
  • 본 논문은 S-파라미터를 어드미턴스 파라미터로 변환하는 것을 바탕으로 비대칭 분배되면서 동시에 임의의 임피던스로 변환시킬 수 있는 임피던스 변환기를 나타내었다. 회로 해석 방법을 우수/ 기수 모드 방법과 비교하면 본 논문의 파라미터 변환을 통한 방법은 위상 지연 정보와 임의의 포트 임피던스 값을 포함시키고 그리고 비대칭 구조등을 해석하는데 간단함을 알 수 있다. 이 설계 방법의 타당성을 확인하기 위해서 중심주파수 1 GHz에서 3:1의 비대칭 분배비율을 갖고 있고 $50{\Omega}$$12.5{\Omega}$ 비율로 변환되는 임피던스 변환기를 설계하였다. 임피던스 변환기를 구현하는 방법은 유도된 수식으로부터 계산된 작은 임피던스 선로를 병렬 오픈스터브가 연결된 전송선로를 사용하여 구현하였고, 이것의 실험 결과는 시뮬레이션 결과와 동일하게 나옴을 확인하였다.

조립과정이 스피커의 전기 및 음향특성에 미치는 영향 (Effects of Electrical and Acoustical Variations for Loudspeaker due to Fabrication Processes)

  • 박석태
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 추계학술대회논문집
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    • pp.155-159
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    • 2004
  • In this paper, it was analyzed the characteristics of electrical and acoustical variations for loudspeaker due to fabrication processes. First, mass of each components of loudspeaker was measured by electric precision scale and performed statistical analysis. Second. Thiele-Small parameters of sample loudspeakers produced by unskilled students were identified by known mass parameter identification method using electrical impedance method and investigated on the variations of each parameter. Electrical impedance tests and acoustic frequency responses were measured on sample loudspeakers and variations were examined to grasp relationship between components variation and fabrication processes. Main factors to effect the changes of electrical impedance were concluded by fabrication processes errors not by components of loudspeaker.

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Online Parameter Estimation for Wireless Power Transfer Systems Using the Tangent of the Reflected Impedance Angle

  • Li, Shufan;Liao, Chenglin;Wang, Lifang
    • Journal of Power Electronics
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    • 제18권1호
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    • pp.300-308
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    • 2018
  • An online estimation method for wireless power transfer (WPT) systems is presented without using any measurement of the secondary side or the load. This parameter estimation method can be applied with a controlling strategy that removes both the receiving terminal controller and the wireless communication. This improves the reliability of the system while reducing its costs and size. In a wireless power transfer system with an LCCL impedance matching circuit under a rectifier load, the actual load value, voltage/current and mutual inductance can be reflected through reflected impedance measuring at the primary side. The proposed method can calculate the phase angle tangent value of the secondary loop circuit impedance via the reflected impedance, which is unrelated to the mutual inductance. Then the load value can be determined based on the relationships between the load value and the secondary loop impedance. After that, the mutual inductance and transfer efficiency can be computed. According to the primary side voltage and current, the load voltage and current can also be detected in real-time. Experiments have verified that high estimation accuracy can be achieved with the proposed method. A single-controller based on the proposed parameter estimation method is established to achieve constant current control over a WPT system.

임펄스전류에 의한 매설지선의 과도임피던스특성에 대한 모의해석 (Simulated Analysis for the Transient Impedance Behaviors of Counterpoises Subjected to the Impulsive Currents)

  • 조정현;이복희
    • 전기학회논문지
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    • 제58권10호
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    • pp.1861-1868
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    • 2009
  • A ground electrode subjected to lightning surge current shows the transient impedance behaviors. The ground electrode for protection against lightning should be evaluated in view of the transient grounding impedance and conventional grounding impedance, not ground resistance. The transient impedance characteristics of ground electrodes are influenced by the shape of ground electrode and the soil characteristics, as well as the waveform of lightning surge current. In order to propose a simulation method of analyzing the transient impedance characteristics of the grounding system in practical use, this paper suggests a theoretical analysis method of distributed parameter circuit model to simulate the transient impedance characteristics of counterpoise subjected to lightning surge current. EMTP and Matlab programs were employed to compute the transient grounding impedances of three counterpoises with different lengths. As a consequence, the simulated results using the proposed distributed parameter circuit model are in good agreement with the measured results.

EMTP를 이용한 매설지선의 규약접지임피던스 해석 (Analysis for the conventional impedance of counterpoise using EMTP)

  • 김종호;조정현;백영환;이강수;이복희
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2009년도 추계학술대회 논문집
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    • pp.47-50
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    • 2009
  • When the lightning currents flow through the ground electrode, the grounding system should be evaluated by the grounding impedance rather than the ground resistance because a grounding system shows the transient impedance characteristic by the inductance of the ground electrode and the capacitance of the soil. The ratio of the peak values of electric potential and currents is the conventional impedance that shows the transient characteristic about impulse currents of the grounding system in a roundabout way. The grounding system having low conventional impedance is a fine grounding system with low electric potential when the lightning currents flow. In this paper the conventional impedance of the counterpoise is calculated by using the distributed parameter circuit model and embodied the distributed parameter circuit model by using the EMTP program The adequacy of the distributed parameter model is examined by comparing the simulated and the measured results. The conventional impedance of the counterpoise is analyzed for first short stroke and subsequent short stroke currents.

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1-l0GHz 대역에서의 SiGe HBT′s 소신호 입력 임피던스 Parameter 추출 방법 (1-10GHz, Input Impedance Parameter Extraction Method of SiGe HBT)

  • 김도형;이상흥;구용서;안철
    • 대한전자공학회:학술대회논문집
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    • 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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    • pp.245-248
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    • 2000
  • In this paper, we present a high-performance SiGe HBT's RF input impedance parameter extraction method. The SiGe HBT has emitter width of 0.5${\mu}{\textrm}{m}$ and length of 6${\mu}{\textrm}{m}$. S-parameter has been measured with the collector current of 1~3㎃ using on-wafer RF measuring system . The pre-calculation method was used in order to overcome the local minimum problem. This method enabled us to extract a RF(1~10㎓) input impedance parameter.

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