• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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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.

• Journal of Power Electronics
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• 제19권5호
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• pp.1326-1335
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• 2019

Common mode (CM) chokes are a crucial part in EMI filters for mitigating the electromagnetic interference (EMI) of switched-mode power supplies (SMPS) and for meeting electromagnetic compatibility standards. However, the parasitic capacitances of a CM choke deteriorate its high frequency filtering performance, which results in increases in the design cycle and cost of EMI filters. Therefore, this paper introduces a negative capacitance generated by a negative impedance converter (NIC) to cancel the influence of equivalent parallel capacitance (EPC). In this paper, based on a CM choke equivalent circuit, the EPCs of CM choke windings are accurately calculated by measuring their impedance. The negative capacitance is designed quantitatively and the EPC cancellation mechanisms are analyzed. The impedance of the CM choke in parallel with negative capacitances is tested and compared with the original CM choke using an impedance analyzer. Moreover, a CL type CM filter is added to a fabricated NIC prototype, and the insertion loss of the prototype is measured to verify the cancellation effect. The prototype is applied to a power converter to test the CM conducted noise. Both small signal and EMI measurement results show that the proposed technique can effectively cancel the EPCs and improve the CM filter's high frequency filtering performance.

• 한국자동차공학회논문집
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• 제16권1호
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• pp.1-7
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• 2008

This paper presents electromagnetic interference(EMI) suppression method applied on the direct current(DC) motor driver for power tail gate control. EMI noise is generated by the fast switching of power devices connected to electric loads. It has become a matter of concern because of the vast increase in the number and sophistication of electronic system in automotive environment. The proposed EMI reduction method is based on the principle of reducing the transient speed of power devices by changing the parameters of the driver circuit related to the power MOSFET. In this paper, power losses were calculated by loss equations and thermal simulation was used to evaluate the effect on printed circuit board. Based on these results, the DC motor driver was fabricated and tested. The proposed method can help to design a DC motor driver which allows it to obtain an acceptable compromise between power losses and EMI.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.494-497
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• 2002

Conducted electromagnetic interference (EMI) from switch mode power supplies (SMPS) has become a major problem due to the proliferation of these devices employing dc-dc converters using standard pulse width modulation (PWM). In this paper, we proposed the sigma-delta modulation $({\sum}{\Delta}M)$ as an alternative switching technique to reduce the conducted EMI in SMPS. A comparative investigation on conducted EMI generated by PWM and ${\sum}{\Delta}M$ techniques are experimentally performed on a 300W Boost converter.

• 마이크로전자및패키징학회지
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• 제27권4호
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• pp.97-105
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• 2020

최근 초고속 이더넷(ethernet)의 데이터 및 동작주파수 속도가 증가하고 있으며, 이에 따라 EMI(electromagnetic interference)가 증가하고 있다. 이러한 EMI의 발생은 주변 전자기기들에 영향을 미쳐 오동작 원인이 될 가능성이 높다. 본 연구에서는 고속 이더넷 스위치 EMI 발생의 주요 원인인 DC-DC SMPS (switching mode power supply)에서 발생하는 EMI 저감을 위해 EMI 필터를 적용하였다. EMI 필터소자는 소형화, 양산화에 장점을 가지며, 내전압(dielectric voltage) 특성이 우수한 MLCC (multi-layer ceramic capacitor)를 사용하였다. MLCC 필터는 X-커패시터 및 X, Y-커패시터로 구성되어 있다. X-커패시터는 10 nF 및 100 nF 용량의 2개의 MLCC와 1개의 마일러 콘덴서(mylar capacitor)로 구성하였다. Y-커패시터는 용량 27 nF의 6개의 MLCC를 사용하여 구성하였다. X-커패시터만을 EMI 필터로 적용한 경우, 전도성(conductive) EMI는 150 kHz ~ 30 MHz의 주파수 대역에서 EMI 전계강도가 허용 한계치를 초과함을 알 수 있었다. 또한 방사성(radiative) EMI도 특정 주파수에서 EMI 전계 강도가 높고, 허용 마진폭도 매우 적음을 알 수 있었다. 반면 X, Y-커패시터를 적용하였을 경우, 전 주파수 대역에서 전도성 EMI가 크게 감소하였으며, 방사선 EMI도 충분한 마진이 확보됨을 알 수 있었다. 또한 X, Y-커패시터의 전기적인 신뢰성을 평가하기 위하여 절연 저항(insulation resistance) 및 내전압 성능을 측정하였으며, 절연 저항 및 내저항 성능이 모두 전기적 신뢰성 기준을 만족함을 알 수 있었다. 결론적으로 MLCC 필터를 X, Y-커패시터로 사용하여 전도성 및 방사성 EMI 노이즈가 효과적으로 감소되었고, 우수한 전기적인 신뢰성도 확보됨을 알 수 있었다.

• Journal of Power Electronics
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• 제18권3호
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• pp.923-930
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• 2018

Based on the application of an integrated dynamic brake (IDB) system that uses a PWM inverter fed-AC motor drive to operate the piston, a new active zero state PWM (AZSPWM) is proposed to improve the stability and reliability of the IDB system by suppressing the conducted electro-magnetic interference (EMI) noise under a wide range of load torque. The new AZSPWM reduces common-mode voltage (CMV) by one-third when compared to that of the conventional space vector PWM (CSVPWM). Although this method slightly increases the output current ripple by reducing the CMV, like the CSVPWM, it can be used within the full range of the load torque. Further, unlike other reduced common-mode voltage (RCMV) PWMs, it does not increase the switching power loss. A theoretical analysis is presented and experiments are performed to demonstrate the effectiveness of this method.

• Journal of Power Electronics
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• 제10권4호
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• pp.342-350
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• 2010

Randomizing the switching frequency (RSF) to reduce the electromagnetic interference (EMI) of switching power converters is a well-known technique that has been previously discussed. The randomized pulse position (RPP) technique, in which the switching frequency is kept fixed while the pulse position (the delay from the starting of the switching cycle to the turn-on instant within the cycle) is randomized, has been previously addressed in the literature for the same purpose. This paper presents a double-hybrid technique (DHB) for EMI reduction in dc-dc switching regulators. The proposed technique employed both the RSF and the RPP techniques. To effectively spread the conducted-noise frequency spectrum and at the same time attain a satisfactory output voltage quality, two parameters (switching frequency and pulse position) were randomized, and a third parameter (the duty ratio) was controlled by a digital compensator. Implementation was achieved using field programmable gate array (FPGA) technology, which is increasingly being adopted in industrial electronic applications. To evaluate the contribution of the proposed DHB technique, investigations were carried out for each basic PWM, RPP, RSF, and DHB technique. Then a comparison was made of the performances achieved. The experimentally investigated features include the effect of each technique on the common-mode, differential-mode, and total conducted-noise characteristics, and their influence on the converter’s output ripple voltage.

• 전력전자학회논문지
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• 제3권4호
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• pp.287-297
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• 1998

RPWM(Random Pulse Width Modulation)은 인버터의 스위칭 주파수를 랜덤하게 변화 시킴으로써 전압, 전류의 고조파 및 소음의 스펙트럼을 광대역에 분산시키는 PWM 기법이다. 스위칭 주파수 또는 펄스의 위치를 랜덤하게 변화시켜 고조파의 불연속적인 이산치 성분을 넓은 영역에 분산시켜 EMI, 진동 등에 좋은 효과를 낼 수 있을 뿐만 아니라, 전력소자의 스위칭에 의해 발생하는 가청 스위칭 소음을 저감할 수 있으므로 근래에 매우 각광 받고 있다. 본 연구에서는 펄스의 위치를 랜덤하게 함으로써 가청 스위칭 소음을 저감할 수 있는 새로운 RPPWM(Random Position Pulse Width Modulation) 방식의 제안 및 구현하였다. 제안된 방식은 각 3상 펄스들의 위치를 변조 구간 내의 임의의 위치에 랜덤하게 배치함으로써 RPWM을 구현하는 방식이다. 이를 위하여 16bit 공성능 마이크로 컨트롤러의 C167을 사용하여, 공각 벡터 변조에 의하여 각 변조 구간에서의 듀티비를 구한 후, 랜덤수 발생기를 이용하여 균일한 분포로 각 상의 펄스를 배치하였다. 그리고 제안된 RPPWM을 이용하여 실험한 결고, 전압, 전류 및 소음의 스텍트럼이 광대역화 되어 전력소자의 스위칭에 의해 발생하는 전동기의 가청 스위칭 소음이 현저히 저감 됨을 확인하였다.

• Journal of electromagnetic engineering and science
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• 제2권2호
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• pp.68-74
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• 2002

In this paper, a pre-layout design approach for high-speed microprocessor is proposed. For multilayer PCB stark up configuration as well as selection and placement of decoupling capacitors, an effective solution for reducing SSN and EMI is obtained by modeling and simulation of complete power distribution system. The system model includes VRM, decoupling capacitors, multiple power and ground planes for core voltage, vias, as well as microprocessor. Finally, the simulation results are verified by measurements data.

• 전력전자학회논문지
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• 제21권1호
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• pp.27-33
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• 2016

A pulse-width modulation (PWM) method for common mode noise reduction in a PWM inverter connected to a single-phase grid is proposed in this study. The extensively used conventional switching method may experience common mode voltage problems, which generate current leakage and electromagnetic induction problems. In the proposed switching method, the neutral point of the output voltage is always fixed at both ends of the input voltage to reduce common mode noise. The validity of the proposed method is proven through simulation and experimental results.