• Journal of Power Electronics
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• v.19 no.1
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• pp.278-287
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• 2019

In this study, a zero-crossing spike current issue in a totem-pole bridgeless power factor correction (PFC) converter is comprehensively investigated for the first time. Spike current occurs when input voltage crosses zero, becomes a noise source, and causes severe common mode emission issues. A generation mechanism for electromagnetic interference (EMI) is presented to investigate the EMI problem caused by zero-crossing issue, and a noise spectrum due to this issue is predicted by a theoretical analysis based on the Fourier coefficient of an approximate spike current waveform. Furthermore, a noise reduction method is proposed and then improved to reduce the spike current. Experimental measurements are implemented on a GaN-based totem-pole bridgeless PFC converter, and the spike current can be effectively suppressed through the proposed method. Furthermore, the noise spectrums measured without and with the reduced zero-crossing spike current are compared. Experimental results validate the analysis of the noise spectrum caused by the zero-crossing spike current issue.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2106-2107
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• 1998

This paper analyzes the sources of EMI noise, and Presents the noise reduction method using the modulation of switching frequency. Modulating the switching frequency makes the noise of side bands by shattering emission spectrum, and then can reduce the size of EMI filter at input line of power supply.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.5
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• pp.451-458
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• 2013

This paper describes a design of LIN MCU using efficient memory accessing architecture which provides concurrent data and address fetch for faster communication. By using slew rate control it can reduce EMI emission while satisfying required communication specifications. To verify the efficiency of the LIN MCU, we developed a SoC and tested for several data packets. Measurements show that this LIN MCU improves network efficiency up to 17.19 % and response time up to 31.26 % for nominal cases. EMI radiation also can be reduced up to 10 dB.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1442-1443
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• 2008

본 논문에서는 인쇄회로기판과 도전체 샤시(Chassis)가 연결되었을 때의 복사성 방사(Radiated Emission)의 감소에 대해서 연구하였다. Current Driven 메커니즘 등가회로를 사용하여 전자파 방사의 주요한 원인중 하나인 Common-mode Current를 인쇄회로기판과 Chassis가 연결된 구조에 적용하였다. Chassis의 유무에 따라 복사성 방사의 감소를 확인하고자 2-layer 인쇄회로기판과 SECC(Steel Electro galvanized Cold-rolled Coil) 재질의 Chassis를 나사(Screw)를 통하여 전기적으로 연결하였을 때를 시뮬레이션 하였고, 제작된 구조물을 3m 무반향실에서 복사성 방사를 측정한 후 시뮬레이션과 결과를 비교하였다. 결과로 30MHz$\sim$45MHz에서 최대 10dB 감소의 효과가 있음을 확인하였다.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1574_1575
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• 2009

This paper investigates the reduction of RE(Radiated Emission) noise in a high power LED module circuit using PWM(Pulse Width Module) switching controller circuit. Poorly designed LED lighting module can experience the RE and CE(Conducted Emission) noise problem. This paper propose the reduction of noise source and improvement of EMI filter design in a high power LED lighting module. The experimental and simulation results showed that reduce the RE noise level effectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.957-967
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• 2008

In this paper, we propose the prediction algorithm of radiation emission from the PCB in an enclosure with a rectangular aperture. PCB scanner is used to measure the near field, which is substituted with an equivalent electric dipole source. Green function and Fourier transform are utilized to represent the electromagnetic fields within and outside the enclosure, respectively. The radiation emission is estimated by using the mode matching technique and surface equivalent theorem. The theoretical results are compared with the measurement to check the accuracy of our analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.3
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• pp.532-538
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• 1997

Exactly aclculated antenna factors are requeired for determining EMI levels in an actual radiated emission test. In this paper, the antenna factors of short dipole antennas above the ground plane are calculated theoretically for the antenna with Roberts balun specified ANSI C63.5 regulation. Also treated is a half-wavelength dipole antenna with Roberts balun to compare the antenna factors with those of resonant dipole antenna. In formulationof antenna factors the antenna is treated as the boundary value problem of Maxwells equations and is analyzed by the Galerkins method of moments. The balun is treated using circuit theory based on power transmission mismatch.

• Proceedings of the KIEE Conference
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• 2007.11a
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• pp.136-137
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• 2007

The emission of external incident field or near device field is important factor of EMI and EMC. In this paper, we apply MOM, using the RWG basis function, to analysis the induced current distribution on the PEC and dielectric plates. The volume and surface integral equations are presented for the electromagnetic wave scattering from plate structures composed of dielectric and conducting objects.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.568-570
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• 2004

A shielding effectiveness of mesh screen filter of plasma display panel (PDP) has been calculated in this paper. Since the screen filter is located near the radiation source, the near field wave impedance of the radiation source, i.e., the PDP electrodes, has been considered to calculate the shielding effectiveness. The near field shielding effectiveness of screen filter at 30${\sim}$300 MHz has been estimated to be more than 65${\sim}$80 dB. The measured shielding effectiveness of screen filter is 10${\sim}$50 dB at 30${\sim}$300 MHz[1]. The resulting discrepancy indicates that there are other EMI emission sources such as emission from PCB and cable besides the PDP electrodes.

• Journal of Electrical Engineering and Technology
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• v.2 no.3
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• pp.306-311
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• 2007

The transient fields generated during switching operations in a Gas Insulated Substation (GIS) are associated with high frequency components in the order of few tens of MHz. These transient fields leak into the external environment of the gas-insulated equipment and can interfere with the nearby electronics. Measurements of the transient fields are thus required to characterise the interference caused by switching phenomena in such substations. In view of the above, E-field emission measurement during a switching operation has been carried out for a 245 kV GIS model, using a resonant dipole antenna and D-dot sensor. The characteristics of the E-fields i.e., frequency spectra and their levels have been analysed and are reported in the paper. Suitability of the measurements has been confirmed by comparing frequency spectra of the measured and computed transient fields.