• Journal of Power Electronics
• /
• 제8권1호
• /
• pp.1-9
• /
• 2008

This paper presents the design and analysis of a new input AC current wave shaping AC-DC converter for cost effective harmonic mitigation under varying loads. The proposed converter consists of a delta-polygon connected autotransformer based twelve-pulse AC-DC converter and a small rating passive shunt filter tuned at $11^{th}$ harmonic frequency. The proposed AC-DC converter eliminates the most dominant $5^{th},\;7^{th}$ and $11^{th}$ harmonics and reduces higher order harmonics; thereby, resulting in an improved power quality at AC mains. Moreover, the design of the autotransformer is modified to make it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. To validate the proposed approach, various power quality indices are presented under varying loads. Experimental results obtained on the developed converter are given to validate the model and design of the proposed converter.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
• /
• pp.950-953
• /
• 2003

In this paper, sigma-delta A/D converter for ADSL modems using oversampling technique is designed. Conventionally, the oversampling A/D converter is consist of opamps, switched capacitors, quantizers, infernal D/A converters, and decimation filters. 3-bit flash A/D converter, 3-bit thermometer-based D/A converters, and sub-blocks are used for high speed operation. HSPICE simulator and CADENCE tool are used for verification and layout of the designed modulator. The internal A/D converter and D/A converters are operated at 130 MHz. In design of decimation filter Matlab is used for calculating coefficients and ModelSim and VHDL are used for design.

• ETRI Journal
• /
• 제35권5호
• /
• pp.819-826
• /
• 2013

A class-D audio amplifier for a digital hearing aid is described. The class-D amplifier operates with a pulse-code modulated (PCM) digital input and consists of an interpolation filter, a digital sigma-delta modulator (SDM), and an analog SDM, along with an H-bridge power switch. The noise of the power switch is suppressed by feeding it back to the input of the analog SDM. The interpolation filter removes the unwanted image tones of the PCM input, improving the linearity and power efficiency. The class-D amplifier is implemented in a 0.13-${\mu}m$ CMOS process. The maximum output power delivered to the receiver (speaker) is 1.19 mW. The measured total harmonic distortion plus noise is 0.015%, and the dynamic range is 86.0 dB. The class-D amplifier consumes 304 ${\mu}W$ from a 1.2-V power supply.

• 조명전기설비학회논문지
• /
• 제29권3호
• /
• pp.69-80
• /
• 2015

This paper is writing about developing magnet power supply. It is very important for power supply to obtain output current in high precision and high stability. As a switching noise and a power noise are the cause of disrupting the stability of output current, to remove these at the front end, low pass filter with 300Hz cutoff frequency is designed and placed. And also to minimize switching noise of the current into magnet and to stop abrupt fluctuations, output filter should be designed, when doing this, we design it by considering load has high value inductance. As power supply demands the stability of less than 5ppm, high precision 24bit(300nV/bit) analog digital converter is needed. As resolving power of 24bit(300nV/bit) analog digital converter is high, it is also very important to design the input stage of analog digital converter. To remove input noise, 4th order low pass filter is composed. Due to the limitation of clock, to minimize quantization error between 15bit DPWM and output of ADC having 24bit resolving power, ${\Sigma}-{\Delta}$ modulation is used and bit contracted DPWM is constituted. And before implementing, to maximize efficiency, simulink is used.

• 한국정보통신학회논문지
• /
• 제5권4호
• /
• pp.630-638
• /
• 2001

본 논문은 기존의 고정밀 오디오 ADC 칩 내에서 통과대역 내에서 발생하는 감쇠 특성을 보상하기 위해 디지털 데시메이션 필터의 구조를 FIR와 IIR 필터를 혼합한 구조를 제시하였다. 제시된 AU 구조에 의해 기존의 디지털 데시메이션 필터 구조 보다 RAM과 MAC크기가 감소됨을 알 수 있었고, 6차 $\Delta\Sigma$ 변조기와 디지털 데시메이션 필터의 특성은 통과대역 내$(\leq\; 0.4535 \times fs)$에서 진폭은 $\pm0.0007dB,\; 0.4535\times fs$ 에서 감쇠는 -0.0013(dB), 저지대역 이상$(\geq\; 0.5465 \times fs)$에서 감쇠는 -110dB였고, 통과대역 내에서 군지연이 30.07/fs〔s〕이고, 군지연 오차가 0.1672%였으며, 군지연 특성은 기존 구조와 유사하였다.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2004년도 학술대회 논문집
• /
• pp.101-104
• /
• 2004

지금까지의 고조파 필터는 중성선 리액터와 이중 엇갈린 결선으로 영상고조파 전류를 제거하였으나 중성선 리액터 과열로 중성선 단선 위험의 문제가 발생하였다. 본 중성선 Open Delta 방식은 이중 엇갈린 결선의 Core Block내에 결선하여 중성선에 연결하면 중성선으로 흐르는 영상 고조파 분 전류를 과열 없이 안전하게 제거하고 중성선 고조파 부하 전류량에 관계없이 완전하게 제거되는 것을 시험 분석한 결과로 가장 효과적인 고조파 저감 대책을 개선사례로 제시하여 관련선로에 도움이 되고자 한다.

• 대한전기학회논문지
• /
• 제41권3호
• /
• pp.244-252
• /
• 1992

This paper describes a reactive power compensator using current-source delta modulation converter, which compensates the reactive power in the ac sides of 3-phase rectifier. In the conventional current control methods for the current-type reactive power compensators, it is usual to compare the reactive reference current signal with the triangular wave and hence to generate the ON-OFF signals for the reactive power compensator. To improve the response as well as the control capability, the delta modulated current control technique is used in this paper. As a result, the input power factor is improved close to unity and both simulation and experimental results show good compensating performances.

• 한국광학회:학술대회논문집
• /
• 한국광학회 2006년도 동계학술발표회 논문집
• /
• pp.367-368
• /
• 2006

• 한국초전도학회:학술대회논문집
• /
• 한국초전도학회 2000년도 High Temperature Superconductivity Vol.X
• /
• pp.193-196
• /
• 2000

A new type low-pass filter design method based on a coupled line and transmission line theory is proposed to suppress harmonics by attenuation poles in the stop band. The design formula are derived using the equivalent circuit of a coupled transmission line. The new low-pass filter structure is shown to have attractive properties such as compact size, wide stop band range and low insertion loss. The seventh-order low-pass filter designed by present method has a cutoff frequency of 0.9 CHz with a 0.01 dB ripple level. The coupled line type low-pass filter with strip line configuration was fabricated by using a high-temperature superconducting (HTS : YBa$_2$Cu$_3$O$_{7-{\delta}}$ thin film on MgO(100) substrate. Since the HTS coupled tine type low-pass filter was proposed with five attenuation poles in stop band such as 1.8, 2.5, 4, 5.5, 6.2 GHz. The fabricated low-pass filter has improved the attenuation characteristics up to seven times of the cutoff frequency.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 2005년도 춘계학술대회논문집
• /
• pp.368-371
• /
• 2005

In this paper, a small band pass filter is designed using new probe type for wireless communication system. In order to provide a band pass filter which can be reduced in dimension, can be reduced in height, and can be surface-mounted. The filter was fabricated using $TE_{01{\delta}}$ mode dielectric resonator. The input/output probes are attached to coner portion of the rectangular metal cavity. Results of the manufactured filter$(12{\times}12{\times}8mm)$ show that the center frequency is 9.953GHz, the insertion loss is -2.98 dB, the 3dB-bandwidth is 15 MHz, and the lode Q is 663.