• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.804-807
• /
• 2005

In this paper, a double scotch yoke mechanism for moving simultaneously the fixed contact and moving contact of a gas circuit brake, is proposed and designed to improve the breaking characteristics of the circuit breaker. Firstly, the design parameters of the scotch yoke are kinematically determined from the desired design condition of the circuit breaker. Next, the stroke curve of the moving contact is designed by considering the design parameter and the specified opening characteristics of electric contacts. Based on the scotch yoke and stroke curve, the dynamics of the electric contacts is analyzed using ADAMS model of switch mechanism.

• 한국전자파학회논문지
• /
• 제25권3호
• /
• pp.259-268
• /
• 2014

본 논문에서는 S-파라메타를 이용한 절연 변압기의 고주파 파라메타 추출 방법을 제안한다. 정상상태에서 회로상수 추출은 고전적 방법인 무 부하, 단락 회로 시험을 통해 나온 측정값을 계산하여 추출하는 방법이 있으며, 본 논문에서는 VNA(Vector Network Analyzer)로 측정한 S-파라메타를 이용하여 추출하는 방법에 대한 연구를 수행하였다. 상용주파수인 60 Hz를 포함한 고주파 대역에서의 변압기 회로상수는 측정한 S-파라메타에 데이터 피팅(최적화) 방식을 이용하여 추출하였다. 기본적으로 절연변압기에서의 고주파 파라메타 추출은 기존에 제시하는 변압기 등가 회로에 표유정전용량(Stray capacitance)을 추가한 등가회로 형태로 제시된다. 이렇게 추출한 회로상수의 S-파라메타와 실제 측정한 S-파라메타 결과를 비교하여 유사함을 확인하였고, 변압기의 1차 측에 신호발생기를 입력한 후, 출력되는 2차 측의 전압과 고주파 등가회로를 이용하여 추출한 2차 측 전압을 비교하여 두 값이 일치하는 것을 확인하였다. 이 결과를 통해 S-파라메타를 이용한 절연 변압기의 고주파 파라메타 추출 방법의 타당성을 입증하였다.

• 전력전자학회논문지
• /
• 제24권5호
• /
• pp.365-371
• /
• 2019

This study shows the feasibility of the parameter of the 1st RC parallel equivalent circuit as a factor of the heat generation of lithium-ion cell. The internal resistance of a lithium-ion cell consists of ohmic and polarization resistances. The internal resistances at various SOCs of the lithium-ion cell are obtained via an electrical characteristic test. The internal resistance is inversely obtained through the amount of heat generated during the experiment. By comparing the resistances obtained using the two methods, the summation of ohmic and polarization resistances is identified as the heating factor of lithium-ion battery. Finally, the amounts of heat generated from the 2C, 3C, and 4C-rate discharge experiments and the COMSOL multiphysics simulation using the summation of ohmic and polarization resistances as the heating parameter are compared. The comparison shows the feasibility of the electrical parameters of the 1st RC parallel equivalent circuit as the heating factor.

• 대한전자공학회논문지TC
• /
• 제48권9호
• /
• pp.47-53
• /
• 2011

본 논문에서는 커넥터의 특성임피던스 추출, 분석 방법 및 설계 변경 방법을 제안하고 임피던스를 정합하여 신호 전달 특성을 개선한다. 3차원 FEM(Finite Element Method) 전자기장(Electro-Magnetic Field) 시뮬레이터를 이용하여 커넥터의 S-파라미터를 계산하고 반사손실 및 삽입손실을 추출한다. 커넥터의 신호 전달 특성은 반사손실이 0.9 GHz 이후부터 -20 dB 이상의 값으로 높게 나타났다. 신호 전달 특성이 낮은 원인을 파악하기 위해서 회로 해석 시뮬레이터를 이용하여 커넥터의 등가 회로 모델을 추출하고 특성임피던스를 계산하였다. 커넥터의 특성임피던스는 $90.3{\Omega}$으로 임피던스 부정합이 발생하여 신호 전달 특성이 저하되었다. 따라서 신호 전달 특성을 개선할 목적으로 임피던스를 정합하기 위해서 커넥터의 커패시턴스를 증가시켰다. 이러한 설계 방안으로 커넥터 신호선의 유효 면적을 확장하고, 커넥터의 몸체 소재로 고유전체를 사용하였다. 설계 변경된 커넥터의 특성임피던스는 $58.6{\Omega}$으로 임피던스 정합에 보다 근접하여 커넥터의 반사손실이 대략 10 dB 향상되었다. 신호선의 유효 면적 증가에 의한 반사손실 개선과 고유전체의 적용으로 전자기파의 신호선 주변 집중에 의해서 삽입손실 또한 개선되었다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.101-102
• /
• 2011

The attraction force is an important parameter for permanent-magnet(PM) linear machines. This paper aims to analysis lumped magnetic circuit model of a magnetic levitation system. It accounts for the fringing effect and leakage flux which may greatly affect the accuracy of the analytical model for the optimal lumped magnetic circuit model. consequentially it will be able to apply to prospective permanent-magnet(PM) linear machines for accurate analysis.

• Journal of Power Electronics
• /
• 제18권4호
• /
• pp.1127-1139
• /
• 2018

A reduced particle-unscented Kalman filter estimation method, along with a splice-equivalent circuit model, is proposed for the state-of-charge estimation of an aeronautical lithium-ion battery pack. The linearization treatment is not required in this method and only a few sigma data points are used, which reduce the computational requirement of state-of-charge estimation. This method also improves the estimation covariance properties by introducing the equilibrium parameter state of balance for the aeronautical lithium-ion battery pack. In addition, the estimation performance is validated by the experimental results. The proposed state-of-charge estimation method exhibits a root-mean-square error value of 1.42% and a mean error value of 4.96%. This method is insensitive to the parameter variation of the splice-equivalent circuit model, and thus, it plays an important role in the popularization and application of the aeronautical lithium-ion battery pack.

• Journal of Electrical Engineering and Technology
• /
• 제7권4호
• /
• pp.589-595
• /
• 2012

When surges and electromagnetic pulses from lightning or power conversion devices are considered, it is desirable to evaluate grounding system performance as grounding impedance. In the case of large-sized grounding electrodes or long counterpoises, the grounding impedance is increased with increasing the frequency of injected current. The grounding impedance is increased by the inductance of grounding electrodes. This paper presents the measured results of frequency-dependent grounding impedance and impedance phase as a function of the length of counterpoises. In order to analyze the frequency-dependent grounding impedance of the counterpoises, the frequency-dependent current dissipation rates were measured and simulated by the distributed parameter circuit model reflecting the frequency-dependent relative resistivity and permittivity of soil. As a result, the ground current dissipation rate is proportional to the soil resistivity near the counterpoises in a low frequency. On the other hand, the ground current dissipation near the injection point is increased as the frequency of injected current increases. Since the high frequency ground current cannot reach the far end of long counterpoise, the grounding impedance of long counterpoise approaches that of the short one in the high frequency. The results obtained from this work could be applied in design of grounding systems.

• 조명전기설비학회논문지
• /
• 제26권2호
• /
• pp.99-105
• /
• 2012

This paper deals with the experimental results of the frequency-dependent resultant ground impedance of vertical ground electrodes installed with a regular n-polygon. In order to propose an effective method of installing the vertically-driven multiple ground electrodes used to obtain the low ground impedance, the resultant ground impedance of ground electrodes installed with a regular n-polygon were measured as functions of the number of ground electrodes and the frequency of test currents and the results were discussed based on the potential interferences among ground electrodes. As a consequence, the effect of potential interference on the resultant ground impedance of vertical ground electrodes is frequency-dependent and it is significant in the low frequency of a few hundreds [Hz]. The resultant ground impedance of multiple vertical ground electrodes is not decreased in linearly proportion to the number of ground electrodes due to the overlapped potential interferences. Also the distributed-parameter circuit model considering the potential interference, the frequency-dependent relative permittivity and resistivity of soil was proposed. The simulated results of the frequency-dependent resultant ground impedance of multiple vertical ground electrodes are in good agreement with the measured data.

• 대한전자공학회논문지TC
• /
• 제37권11호
• /
• pp.17-22
• /
• 2000

HBT의 하이브리드 파이 등가회로모델에 대한 새롭고 안정적인 파라메터 추출방법을 제안한다. 측정된 S-파라메터로부터 베이스 내부 저항을 정확히 계산 할 수 있는 식이 유도 되었으며 이 식은 외부 접근 인덕턴스의 값에 크게 민감하지 않다. 이를 기반으로 다른 파라메터를 위한 6 개의 해석적 표현식이 개발되었고 하이브리드 파이 등가회로 모델링을 위한 이 식들은 안정적이고 빠르며 신뢰성 있는 파라메터 추출을 가능케한다.

• 조명전기설비학회논문지
• /
• 제26권3호
• /
• pp.73-79
• /
• 2012

A counterpoise is commonly employed in grounding systems installing near the ground surface of low resistivity soils and radial-type counterpoises are used in the limited space. Recently some studies on the evaluation of ground impedance of paralleling ground electrodes have carried out, but the data for providing the frequency-dependent ground impedances considering potential interferences are not yet sufficient. In order to provide the information about the design of grounding systems for surge protection, the simulations of the frequency-dependent ground impedance of various shaped counterpoises are carried out by using the distributed parameter circuit model including the effect of potential interferences. This paper presents the theoretical simulations and actual experiments of the frequency-dependent ground impedance of paralleling and 3 or 4-arms star counterpoises. The accuracy of the simulation methodology is examined by the comparison with the measured results, and the results show a good agreement between the simulation and the experiment.