• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.380-383
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• 1990

When the MOSPET is applied as a switching device for the resonant inverter, a damped oscillating noise is appeared at specific frequency band. This damped Oscillation is caused by the series and parallel resonance due to distributed circuit parameter of snubber and main circuit. This paper describes the frequency-impedance characteristic of the resonant inverter and optimal snubber design strategy to reduce the RF noise.

• 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.

• 전력전자학회논문지
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• 제26권3호
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• pp.176-182
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• 2021

This research proposes a high-frequency circuit that can accurately predict the differential mode noise of single-phase inverters at the circuit design stage. Proposed single-phase inverter high frequency circuit in the work is a form in which harmonic impedance components are added to the basic single-phase inverter circuit configuration. For accurate noise prediction, parasitic components present in each part of the differential noise path were extracted. Impedance was extracted using a network analyzer and Q3D in the measurement range of 150 kHz to 30 MHz. A high-frequency circuit model was completed by applying the measured values. Simulations and experiments were conducted to confirm the validity of the high-frequency circuit. As a result, we were able to predict the resonance point of the differential mode voltage extracted as an experimental value with a high-frequency circuit model within an approximately 10% error. Through this outcome, we could verify that differential mode noise can be accurately predicted using the proposed model of the high-frequency circuit without a separate test bench for noise measurement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.324-327
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• 1996

This paper presents the adoption of PWM converter to enhance input power factor in inverter arc welder. By using PWM converter in inverter arc welder, the disadvantages of bridge diode converter such as low input power factor is improved, new NCT(Noise Cut Transformer) is designed to reduce noise which has harmful effect in switching component, half bridge PWM inverter is adopted to reduce cost in inverter arc welder.

• 전기학회논문지
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• 제61권7호
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• pp.1061-1068
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• 2012

In this paper, The Next Generation High Speed Railway inverter system using Hybrid Random Pulse Width Modulation (Hybrid RPWM) is proposed to reduce electromagnetic noise. To verify the validity of study, simulation results of the Next Generation High Speed Railway Inverter system using the proposed method was compared with the system using conventional method. A simulation program is developed using Matlab/Simulink. The results show that the voltage and current harmonics of the Next Generation High Speed Railway Inverter system using Hybrid RPWM significantly decrease and spread into wide band area.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.311-314
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• 1995

PWM(Pulse-Width Modulation) is frequently used as control method for inverter. In control of active silencer studied presently, PWM control method can be applied. This paper presents its possibility. As operating source of loudspeaker, inverter is used instead of audio amplifier and PWM controller controls the inverter to make canceling sound. This paper presents that active silencer of inverter-type using the PWM control method makes the canceling sound to acoustic noise and cancels the acoustic noise.

• Journal of Electrical Engineering and Technology
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• 제4권2호
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• pp.255-265
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• 2009

This paper presents the acoustic noise and mechanical vibration reduction of a coreless brushless DC motor with an air dynamic bearing used in a digital lightening processor. The coreless brushless DC motor does not have a stator yoke or stator slot to remove the unbalanced force caused by the interaction between the stator yoke and the rotor magnet. An unbalanced force makes slotless brushless DC motors vibrate and mechanically noisy, and the attractive force between the magnet and the stator yoke increases power consumption. Also, when a coreless brushless DC motor is driven by a $120^{\circ}$ conduction type inverter, high frequency acoustic noise occurs because of the peak components of the phase currents caused by small phase inductance and large phase resistance. In this paper, a core-less brushless DC motor with an air dynamic bearing to remove mechanical vibration and to reduce power consumption is applied to a digital lightening processor. A $180^{\circ}$ conduction type inverter drives it to reduce high frequency acoustic noise. The applied methods are simulated and tested using a manufactured prototype motor with an air dynamic bearing. The experimental results show that a coreless brushless DC motor has characteristics of low power consumption, low mechanical vibration, and low high frequency acoustic noise.

• 한국음향학회지
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• 제22권5호
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• pp.337-344
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• 2003

자기부상열차의 가장 중요한 소음원인 VVVF 인버터와 DC/DC 컨버터는 탄성체인 코어가 MS (Magnetostriction)에 의해 가진되어 소음을 발생한다. DC/DC 컨버터는 변압기가 주원인이며 소음/진동 스펙트럼에 가진주파수의 하모닉성분이 뚜렷하게 나타난다. 반면, LIM/VVVF 인버터소음은 가진주파수의 하모닉성분은 미약한 대신 변환주파수의 하모닉성분이 매우 강하게 나타난다. VVVF 인버터소음에서 변환주파수를 올리면 하모닉성분이 고주파수대역으로 이동하는데 700 ㎐를 2㎑로 올리면 소음이 5-6 ㏈ 감소되는 것으로 나타났다. 현 기술수준으로 MS에 의한 탄성체의 소음/진동을 정량적으로 예측하기는 어려운 실정이므로 본 논문에서는 정성적으로 MS에 의한 가속도 스펙트럼을 예측하였고 VVVF 인버터에 대해 변환주파수 증가의 효과를 확인할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 A
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• pp.420-423
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• 1995

The electric arc welding machine with high-frequency inverter is studied in this paper which could make more saving in energy than conventional ones with inherent low efficiency. The inverter circuit has been already adopted to special welding machines such as MIG and TIG for improving operating performances so much. But this adoption has not be applied to conventional ac arc welding machine until now. The proposed technology for higher efficiency is to apply the high frequency inverter, together with noise-cut transformer. Overall output characteristics are investigated in aspect of cost and circuit performance. The proposed system is conducted practical experiments using PWM controller.

• 전력전자학회논문지
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• 제12권5호
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• pp.386-393
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• 2007

본 논문에서는 CIM(Current Injection Method)을 이용한 charge-pump방식의 plasma backlight용 고압 inverter회로를 제안한다. 고압 inverter에서 에너지 회수회로의 채용은 새로운 시도로서 에너지회수 이외에도 noise에 의한 시스템의 불안정성과 방전안정화에 기여하고 있다. charge-pump방식으로 스위치류의 내압을 저감하므로 cost면에서 매우 유리한 조건을 확립하였으며 CIM(Current Injection Method)방식의 적용으로 high speed 에너지 회수를 가능하게 하였다. 그리고 제안회로의 동작을 모드별로 해석하였으며, 실제 32" 패널에 적용하여 실험함으로써 제안한 회로의 유용성을 입증하였다.