• Journal of Power Electronics
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• 제11권4호
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• pp.490-498
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• 2011

This paper presents a novel analysis, design, and implementation of a battery charging three-phase high frequency semi-controlled power converter feasible for plug-in hybrid electric vehicles. The main advantages of the proposed topology include high efficiency; due to lower power losses and reduced number of switching elements, high output power density realization, and reduced passive component ratings proportionally to the frequency. Additional advantages also include grid economic utilization by insuring unity power factor operation under different possible conditions and robustness since short-circuit through a leg is not possible. A high but acceptable total harmonic distortion of the generator currents is introduced in the proposed topology which can be viewed as a minor disadvantage when compared to traditional boost rectifiers. A hysteresis control algorithm is proposed to achieve lower current harmonic distortion for the rectifier operation. The rectifier topology concept, the principle of operation, and control scheme are presented. Additionally, a dc-dc converter is also employed in the rectifier-battery connection. Test results on 50-kHz power converter system are presented and discussed to confirm the effectiveness of the proposed topology for PHEV applications.

• Journal of Electrical Engineering and Technology
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• 제12권5호
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• pp.1872-1882
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• 2017

Medium voltage drive systems driven by high-power multi-level inverters operating at low switching frequency can reduce the switching losses of the power device and increase the output power. Employing subsection synchronous current harmonic minimum pulse width modulation (CHMPWM) technique can maintain the total harmonic distortion of current at a very low level. It can also reduce the losses of the system, improve the system control performance and increase the efficiency of DC-link voltage accordingly. This paper proposes a subsection synchronous CHMPWM approach of active neutral point clamped five-level (ANPC-5L) inverter under low switching frequency operation. The subsection synchronous scheme is obtained by theoretical calculation based on the allowed maximum switching frequency. The genetic algorithm (GA) is adopted to get the high-precision initial values. So the expected switching angles can be achieved with the help of sequential quadratic programming (SQP) algorithm. The selection principle of multiple sets of the switching angles is also presented. Finally, the validity of the theoretical analysis and the superiority of the CHMPWM are verified through both the simulation results and experimental results.

• 전력전자학회논문지
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• 제8권5호
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• pp.381-388
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• 2003

본 논문에서는 IED(Intelligent Electronic Devices)에서의 고조파 문제를 연구하였다. 최근 전력전자 기술의 급격한 발전으로 비선형부하에 의한 전력 품질의 왜곡이 심각해지고 있다. 연속적인 고조파 전류는 전련기기의 수명을 단축시키고 발열 문제가 발생하며 비정상적인 동작을 유발한다. 이러한 문제를 해결하기 위한 디지털 보호계전 시스템에서 전통적인 방법으로 전력을 계측하면 고조파의 영향을 고려할 수 없다. 이러한 문제를 해결하기 위하여 본 연구에서는 TMS320C32 DSP와 CPLD를 이용한 IED prototype을 구현하여 실험을 통해 성능을 확인하였다.

• 한국통신학회논문지
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• 제12권4호
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• pp.386-398
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• 1987

本 論文은 PWM(Pulse Width Modulation)인버어터의 스위칭作用에 의해서 發生하는 高周波 影響을 最小化하기 위한 Suboptimal PAWM(Pulse Amplitude Width Modulation)을 提示하였다. 本 方式은 Suboptimal PWM에서 THD(Total Harmonic Distorition)가 最小가 되는 固定點(基本波 電壓 u1=1.2)에서 하나의 스위칭패턴을 決定하였다. 그리고 電壓은 DC Link에서 DC Chopper에 의해 制御하게 하고 인버어터에서는 단지 高周波만을 制御하도록 하였다. 本 方式은 3相 誘導電動機의 VSD(Variable Speed Drive)에 適用하여 電動機의 騷音, 인버어터의 線間電壓 및 電流, 電流高周波 스펙트럼을 測定하였으며, 他 方式과 比較해 보았다. 그 結果로부터 本 方式의 妥當性을 立證할 수 있었다.

• 한국소음진동공학회논문집
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• 제17권9호
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• pp.847-852
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• 2007

Design aspects of a bearing casing system of a power plant are mainly focused on the strength and weight of itself to have a more stable system. Since the rotor speed often passes through the critical speed region when the operation begins, the relation between the rotating frequency of the rotor and natural frequency of the casing is very important for a prevention of resonance. However, harmonic components above the rotating frequency have often been overlooked the design for the resonance avoidance. In this paper, it is revealed that resonance vibration is generated when the natural frequency of a bearing casing is close to the one of harmonics of basic rotating frequency(1x), and as a consequence, sensing qualify of seismoprobes attached to the bearing casing structure can be seriously damaged. In order to reduce the resonance vibration, some stiffeners are added to the casing structures. Significant reduction in the magnitude of vibration corresponding to 2x harmonic of basic rotating frequency is observed from both FE analysis and experiment.

• Journal of electromagnetic engineering and science
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• 제14권2호
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• pp.47-53
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• 2014

This paper presents a high gain and high harmonic rejection low-noise amplifier (LNA) for software-defined radio receiver. This LNA exploits the high quality factor (Q) series resonance technique. High Q series resonance can amplify the in-band signal voltage and attenuate the out-band signals. This is achieved by a source impedance transformation. This technique does not consume power and can easily support multiband operation. The chip is fabricated in a $0.13-{\mu}m$ CMOS. It supports four bands (640, 710, 830, and 1,070MHz). The measured forward gain ($S_{21}$) is between 12.1 and 17.4 dB and the noise figure is between 2.7 and 3.3 dB. The IIP3 measures between -5.7 and -10.8 dBm, and the third harmonic rejection ratios are more than 30 dB. The LNA consumes 9.6 mW from a 1.2-V supply.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.15-21
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• 2009

High-order harmonic generation from a solid surface affected by the contrast of a laser pulse was studied using an oscillating mirror model. High-order harmonics generated from solid surfaces have unusual properties such as spectral redshift, and an intensity difference between even- and odd-order harmonics which is not reported for high-order harmonics generated by a gas medium. We confirmed that high-order harmonics from solid surfaces have selectivity of polarization as well as cut-off extension and the enhancement of conversion efficiency proportional to laser intensity. And the principle of operation and the characteristics of a plasma mirror system developed for achieving high contrast laser pulses to pursue the experimental realization of high-harmonic generation from solid surfaces are reported. Energy fluence on the plasma mirrors is tunable between $10\;J/cm^2$ and $1000\;J/cm^2$ and around 1000 shots are available before the plasma mirrors require replacement.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).

• 전자공학회논문지
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• 제49권10호
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• pp.233-239
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• 2012

전력 계통에서 발생하는 고조파는 전동기 등 기기 오동작 및 고장, 불필요한 전력 소모 등을 야기시킨다. 고조파 발생에 대한 근본적인 대책은 고조파 발생 원인을 찾아 제거하는 것이며 본 논문에서는 아날로그 디바이스사의 ADE7880을 이용하여 고조파 발생 원인을 실시간으로 파악할 수 있는 전력품질 측정장치를 제작하고 동작을 검증하여 다양한 전력 품질 측정 분야에 활용할 수 있도록 하였다. 전력은 일반적으로 45Hz에서 66Hz까지의 라인 주파수를 가지고 있는데, 본 연구에서 사용한 ADE7880 필터대역인 2.8kHz 밴드 내에서 분석될 수 있는 고조파의 수는 2800/f로 최대 2800/45 = 63차 고조파까지 가능하며, 라인주파수가 60Hz인 한국에서의 최대 고조파차수는 2800/60 = 46차까지 측정할 수 있었다. 또한 전압, 전류, 전력 측정의 정확도는 0.1%이내의 오차를 가져 매우 정밀한 수준임을 확인하였다.

• 전기학회논문지
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• 제62권9호
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• pp.1240-1248
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• 2013

This paper describes a switching-level operation analysis of BTB(Back-To-Back) converter for HVDC(high voltage DC) application based on MMC(modular multi-level converter). A switching-level operation analysis for BTB converter is very important to understand the converter operation in detail and check the voltage and current transients in each components. However, the development of switching-level simulation model for the actual size BTB Converter is very difficult because the MMC normally has more than 150 sub-modules for each arm. So, a switching level simulation model for the 11-level MMC-based BTB converter was developed with PSCAD/EMTDC software, which has 12 sub-modules for the positive arm and another 12 sub-modules for the negative arm. The DC-voltage balance algorithm, the circulating-current reduction algorithm, the harmonic reduction algorithm, and the redundancy operation algorithm were included in this simulation model. The developed simulation model can be utilized to analyze the MMC-based BTB converter for HVDC application in switching level and to develop the protection scheme for the MMC-based BTB converter for HVDC application.