Yeon-Choon Chung

Circuit Model Analysis for Traces that Cross a DGS

This paper presents a novel modeling technique for traces that cross a defected ground structure. A simple and accurate equivalent circuit model provides clear insight into the coupling mechanism between a microstrip line and a slot or split. The circuit models consist of a transformer as the coupling mechanism and LC resonators as the ground with a slot or split structure. Resistors, capacitors, and inductors are added to the model to increase accuracy and equivalence at high frequency. Simulated and measured S-parameters are presented for defected ground structures. The accuracy and validity of the proposed equivalent circuit model is verified by evaluation of the S-parameter characteristics of the defected ground structures and comparison with measured results.

Study on the High-Frequency Circuit Modeling of the Conducted-Emission from the Motor Drive System of an Electric Vehicle

본 논문에서는 고주파 회로 모델링을 이용하여 전기자동차의 모터 구동 시스템으로부터 방출되는 전도성 전자파 노이즈를 시스템-레벨에서 분석하였다. 관련 전도 방출의 주요 원인은 모터 구동 시스템에서 사용하는 펄스폭 변조방식의 스위칭 동작에 기인하며, 이러한 전도 방출은 공통-임피던스 결합 및 유도성 결합을 통해 AM/FM 주파수 대역에서의 무선주파수 간섭을 유발한다. 이러한 문제를 분석하기 위해 모터 구동 시스템을 구성하고 있는 IGBT와 고압 커패시터, 인버터, 모터 및 고전압 케이블과 버스 바에 대한 기본 회로는 물론, 각 부분에서 존재하는 기생 성분 및 비선형 특성을 해석하여 모터 구동 시스템 전체를 포함한 시스템-레벨의 고주파 등가회로 모델을 제안하였다. 이러한 모델을 이용한 모터 구동시스템의 전도 방출 특성을 시뮬레이션하고, 측정하였으며, 비교적 큰 해석구조임에도 불구하고 두 결과가 비교적 잘 일치함을 확인하였다. 향후 이러한 접근방법이 전기자동차의 전자파 적합성 설계에 효과적으로 사용될 수 있을 것으로 기대한다.

Analysis on the RFI Noise Path of Electrical Railway System in the Frequency Range of 9 kHz to 150 kHz

The interaction of magnetic field in the frequency range of 9~150 kHz radiating from a railway system with wireless systems has been the cause of radio frequency interference. In this paper, the equivalent circuit model of the RFI noise is proposed through source and transfer path analysis, and it is confirmed that the switching noise of several kHz that occurs a vehicle traction drive system and a substation is radiated by forming the loop circuit with a feeder line by a rolling stock. And the validity of the proposed equivalent circuit model is verified by analyzing the effects of RC banks installed in the real railway between Guri and Guksu stations, the RFI noise can be effectively mitigated by loading suitable capacitance between rail and feeding line.

Alternative investigation of common-mode radiated emission from PCB with a bent signal line and attached cables

The common-mode radiated emission from PCB with a bent signal trace and attached cables and the trend of S-parameters according to the length of horizontal signal trace have been investigated. In the case where the total signal length is kept constant, it is ensured from the results that as the horizontal signal line in parallel with attached cables becomes longer, the radiated emission level due to the current-driven mechanism increases while there is no variation in radiated emission level due to the voltage-driven mechanism.

High-Frequency Circuit Modeling of the Conducted-Emission from the LDC System of a Electric Vehicle

In this paper, conducted emission from the LDC(Low-Side DC/DC Converter) of a HEV/EV was analyzed using high-frequency circuit modeling in system-level approach. The conducted emission by PWM process(100 kHz; Switching Frequency) can cause RFI(Radio-Frequency Interference) problems in the AM/FM frequency range. In order to mitigate this conducted emission, a high-frequency equivalent circuit model is proposed by analyzing the fundamental circuits, parasitic components in their parts and connections and non-linear characteristics of MOSFETs, high-power capacitors, inverters, motors, high-power cables, and bus bars which are composed of the LDC. Using these circuit models, results of both simulation and measurement were compared and similarities between them were verified. We are looking forward that this approach can be effectively used in the EMC design of HEV/EV.

Improvement of Electromagnetic Environment Effects in aLift System by Installing a Mobile-Communication Repeater

본 연구의 목적은 전자파 적합성을 고려하여 승강기 시스템 내에 중계기 안테나를 설치하는 방안을 제안하는 것이다. 승강로에 중계기 안테나를 설치하는 경우(Solution 1)와 승강기 내부에 중계기 안테나를 설치하는 경우 (Solution 2)의 2가지 solutions을 검토하였으며, Solution 2가 Solution 1보다 효과적임을 확인하였다. 또한, 승강기에 대한 전자파 내성 기술 기준과 20 dB의 안전 마진을 고려하여 중계기 안테나의 출력(EIRP)을 -5 dBm으로 제한할 것을 제안하였으며, 이러한 출력은 이동 통신 시스템의 정밀 전력 제어 메커니즘에 따라 최적의 안정된 전자파 환경을 제공함을 확인하였다. 이러한 접근은 무선을 활용하여 오히려 전자파 환경을 개선할 수 있음을 보여준 본 연구가 Green ICT의 중요한 사례가 될 수 있다.

An Effective Mitigation Method on the Signal-Integrity Effects by Splitting of a Return Current Plane

Generally a return current plane(RCP) of high speed digital and analog part is partitioned. This is achieved in order to decrease the noise interference between subsystem in PCBs(Printed Circuit Boards). However, when the connected signal line exists between each sub system, this partition will cause unwanted effects. In a circuital point of view, RCP partition has a bad influence upon signal integrity. In a EMI(Electromagnetic Interference) point of view, the partition of the return current plane becomes a primary factor to increase the radiated emission. Component bridge(CB) is usecl for the way of maintaining signal integrity, still specific user`s guide doesn`t give sufficient principle. In a view point of signal integrity, design principle of multi-CB using method will be analyzed by measurement and simulation. And design principle of noise mitigation will be provided. Generally interval of CB is ferrite bead. In this study. When multi-CB connection is applied, design principle of ferrite bead and chip resistor is proved by measurement and simulation. Multi-connected chip resistance is proved to be more effective design method in the point of signal integrity.

Study on the Introduction of EMC Engineering System in Korea

In order to ensure the safety of the large-scale public facilities, the analysis of EMC(ElectroMagnetic Compatibility) of electronic systems included in the facilities is very necessary. The reason is that the system-level EMC of the facility could be not guaranteed, even if individual equipments included in the facility are satisfied with their EMC requirements. As a result, the system-level evaluation and analysis of EMC should be carried out in order to establish the reliable operations of safety and mission-critical electronic systems. This paper analyze the relevant legal systems of domestic and other countries, and furthermore case studies of system-level EMC approaches were analyzed in the specific applications of electric railways, building, automobile, petroleum refinery systems. And the introduction of related systems in Korea is proposed, and main parts and problems to be looked at each proposed measures are discussed. The results are expected to be utilized in the introduction of the system-level EMC engineering, and contributed in national security and the protection of people`s life, body and their properties.

The Propose of EMI Limits for GETM Cell Using Correlation Factor between OATS and GTEM Cell

This study is about the limits of GTEM cell using correlation factor between the OATS(Open area Test Site) and the GTEM cell. First, the field strengths at the 10 m distance OATS and in GTEM cell to obtain the experimental correlation factor are measured. Also, the EMI limits of radiated power are derived in GTEM cell as 3 position method is inversely transformed. The field strengths that calculated from theoretical models by 3 and 15 position methods are programmed and compared with measured data at the OATS. As the EMI limits of GTEM cell is newly defined, it will be use to substitute GTEM cell for OATS to efficiently measure EMI(Electromagnetic Interference).

Study on the Radiation Pattern of Radiated Emission above 1 GHz

The purpose of this study is to analyze the radiation-pattern characteristics above 1 GHz for the electromagnetic wave radiated from multi-slot such as ventilations, etc. on the enclosure of an EUT and so to make recommendations for suitable test methods. An experimental EUT was formed by putting a comb-generator at the center of a rectangular enclosure with 4 slots, and its radiation pattern was analyzed in the frequency range of 1~6 GHz. As analysis results, multi-lobe appears above 2 GHz and the number of multi-lobes is growing as the frequency increases. And real radiated-emission measurements were performed for the experimental EUT by scanning a receiving antenna in the height of 1~4 m and tilting toward maximum radiation, as well as setting the height of a receiving antenna to the central position of the EUT which is prescribed at the present standards. The measured results are +12.8 dB in the scanning and +16.4 in the scanning and tilting compared with the present standard test method. Therefore, the latter must be revised in order to consider the radiation pattern above 1 GHz.