• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1879-1881
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• 1998

The conducted differential mode (DM) EMI in a flyback converter are analyzed. Circuit modeling of passive components and PCB pattern for the EMI simulation are presented. Using the model, high frequency noise path is analyzed. The analyses are verified with simulations by identifying the peakings of the EMI pattern.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.21-22
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• 2015

플라이백 컨버터에서 발생하는 EMI 공통모드 잡음은, 스위치 turn-off에서 1차 측 누설 인덕턴스로 인한 기생 진동과 turn-on에서 발생하는 2차 측 출력회로의 기생 진동으로 구성된다. 차동모드 잡음은 직류전원의 스위칭 전류로 인한 전압 강하 성분으로 나타나며 직류전원 임피이던스에 비례하여 증가한다. 1차 측 기생진동은 느린 속도의 일반 다이오드와 직렬저항 삽입으로, 2차 측기생진동은 정류 다이오드의 RC 스너버로 감소 시킨다. 누설 인덕턴스가 큰 UU코어 EMI 필터가 잡음 감소에 유효함을 보인다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.6 no.1
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• pp.48-65
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• 1995

This paper deals with the analysis of the unintentional radiation from the TDX-1B subscriber Board. According to the demand of digital systems and developement of high speed switching devices, electro- magnetic noise intensity and it's bandwidth occupancy in spectrum are increasing and so there is a serious possibility causing the various EMI phenomena. More accurate radiation model was established by using the Finite Difference Time Domain (FDTD) analysis, and the EMI probabilistic analysis of the digital switching system was performed. For validating the proposed model and its calculated results, on-promises test was performed and compared with the calculated results. These results may be applicable to be used for EMI model in large digital system, and prediction of EMI effect from a large digital system, and the EMI control design when designing digital system to meet inter- national EMI regulation.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.761-767
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• 2001

In this paper, filtering techniques to reduce the adverse effects of motor leads on high-frequency PWM inverter fed AC motor drives will be examined. The filter was designed to keep the motor terminal from the cable surge impedance to reduce overvoltage reflections, ringing, and the dv/dt, di/dt. Therefore, filtering techniques are investigated to reduce the motor terminal overvoltage, ringing, and EMI noise in inverter fed ac motor drive systems. The output filter is used to limit the rate of the inverter output voltage and reduce EMI(common mode noise) to the motor. The performance of the output filter is evaluated through simulations (PSIM) and experiment on PWM inverter-fed ac motor drive(3phase, 3hp(2.2kw), input voltage 220/380V, induction motor). An experimental PWM drive system reduction of conducted EMI was implemented on an available TMS320C31 microprocessor control board. Finally, experimental results showed that the inverter output filter reduces more CM noise than the LPF(low pass filter) and reduce overvoltage and ringing at the motor terminal.

• Journal of IKEEE
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• v.22 no.2
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• pp.510-513
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• 2018

Recently, EMC (electromagnetic compatibility) becomes very important, which demands the measurement of EMI (electromagnetic interference) in the chip level. NFS (near-field scanning) systems defined in IEC 61967 and IEC 62508 are typical methods to analyze EMI in the chip level. As chips becomes faster, frequency measurement of NFS system should become wideband, but it degrades SNR (singal-to-noise ratio) of the NFP (near-field probe). This paper surveys SNR enhancement technologies of the NFS while maintaining wideband characteristics.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.5
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• pp.265-270
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• 2006

In this paper EMI problems with induction motor drive system using multi-level inverters are investigated. The high power multi-level inverter usually operates with low switching frequency and produces large noises. Generally, EMI consists of the conduction component through source lines and emission component emitted to the space. This conduction component can be classified to the common-mode between source line and ground, and the normal-mode between lines. The EMI filters for the induction motor drive system are designed and implemented to reduce EMI noise. Finally the designed system is verified by the experiment. The experimental results show that both the normal mode and common mode noises are greatly reduced compared to the system without filters.

• Journal of Power Electronics
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• v.11 no.5
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• pp.767-777
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• 2011

Power electronic systems such as switching power supplies are accounted as noise sources for other sensitive circuits. EMI caused by power converters can disturb the normal operation of the converter and other adjacent systems. Major research is concentrated on EMI mitigation for power converters in which the main concern is compliance with EMC standards to ensure proper operation of converters and nearby systems. This paper reviews EMI reduction techniques related to switching power converters with emphasis on the conducted EMI. A comprehensive review of significant research works is performed and various methods are thoroughly discussed and compared. Also, a classification of methods is presented. Moreover, converter prototypes are realized which contain several EMI mitigation techniques and their effects are presented via experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.2 s.117
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• pp.199-205
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• 2007

In this paper, a novel hexagonal-shaped electromagnetic bandgap(EBG) power plane for the suppression of the ground bounce noise(GBN) in high-speed circuits is proposed. The proposed structure consists of hexagonal-shaped unit cells and detoured bridges connecting the unit cells. The hexagonal-shaped unit cells could omni-directionally suppress the GBN in digital circuits. The fabricated power plane's omni-directional -30 dB suppression bandwidth is from 330 MHz to 5.6 GHz. Then the proposed structure suppresses electromagnetic interference(EMI) caused by the GBN within the stopband. As a result, the proposed structure is expected to be conducive solving EMI problem in high-speed circuits.

• 전기의세계
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• v.41 no.1
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• pp.23-34
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• 1992

일반적으로 전자파 노이즈는 발생원인에 따라 2가지로 대별되는데, 태양 노이즈와 낙뢰 등으로 대표되는 자연노이즈(Natural Noise)와 통신, 방송, 전자기기 등과 같은 인공노이즈(Man-Made Noise)가 있다. 인공노이즈는 다시 의도성노이즈(Intentional Noise)와 비의도성노이즈(Unintentional Noise)로 분류된다.

• Journal of Power Electronics
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• v.19 no.1
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• pp.296-306
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• 2019

The flyback topology is being widely used in power adapters. The coupling capacitance between primary and secondary windings of a flyback transformer is the main path for common-mode (CM) noise conduction. A Y-cap is usually used to effectively suppress EMI noise. However, this results in problems in space, cost, and the danger of safety leakage current. In this paper, the CM noise behaviors due to the electric field coupling of the transformer windings in a flyback adapter with synchronous rectification are analyzed. Then a scheme with balance winding is proposed to reduce the CM noise with a transformer winding design that eliminates the Y-cap. The planar transformer has advantages in terms of its low profile, good heat dissipation and good stray parameter consistency. Based on the proposed scheme, with the help of a full-wave simulation tool, the key parameter influences of the transformer PCB winding design on CM noise are further analyzed. Finally, a PCB transformer for an 18W adapter is designed and tested to verify the effectiveness of the balance winding scheme.