• 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.

• Journal of Power Electronics
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• 제17권1호
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• pp.115-126
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• 2017

This paper presents a new cascaded asymmetrical single phase multilevel converter with a reduced number of isolated DC sources and power semiconductor switches. The proposed inverter has only two H-bridges connected in cascade, one switching at a high frequency and the other switching at a low frequency. The Low Switching Frequency Inverter (LSFI) generates seven levels whereas the High Switching Frequency Inverter (HSFI) generates only two levels. This paper also presents a solution to the capacitor balancing issues of the LSFI. The proposed inverter has lot of advantages such as reductions in the number of DC sources, switching losses, power electronic devices, size and cost. The proposed inverter with a capacitor voltage balancing algorithm is simulated using MATLAB/SIMULINK. The switching logic of the proposed inverter with a capacitor voltage balancing algorithm is developed using a FPGA SPATRAN 3A DSP board. A laboratory prototype is built to validate the simulation results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.447-448
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• 2012

With wireless power transfer the of ECR device the designed with a high-frequency and high frequency AC power to the device that may enter the high-frequency switching inverter to be possible. In this paper, is designed to 2MHz switching frequency by using ECR device capable of 2MHz Class ${\Phi}_2$ inverter was designed as a wireless power transmission.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.326-328
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• 2005

In order to reduce the capital and overall operating cost of a fuel-cell system, a high-efficiency fuel-cell power inverter with a simple framework is required. The high-order two-inductance two-capacitance (LLCC) resonant technique is adopted in this study to implement a low-frequency 60-Hz sine wave voltage inverter utilized in the proton exchange membrane fuel-cell (PEMFC) system. The methodology for inverting dc voltage into low-frequency ac boltage is usually generated by the pulse-width-modulation (PWM) technique. However, the PWM-type inverter output has high-frequency harmonic components. Although an adequately designed filter could be utilized to overcome this problem, there are still some undesirable effects introduced by the high-frequency switching loss, electromagnetic-interference, harmonic current, and load variation. A novel power inverter via the LLCC resonant technique is designed for inverting dc voltage into 60-Hz ac sine wave voltage in the PEMFC system. This circuit scheme has the merits of low harmonic components, soft switching, high efficiency, and simplified implementation. The effectiveness of the proposed resonant inverter used for the PEMFC system is verified by numerical simulations and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.323-326
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• 1999

For decrease the harmonic current components of the power source, a first method is insert the choke coil that used the choke input type rectifier, the booster chopper circuit and buck chopper circuit. And the several method are studying like as the PWM(Pulse Width Modulation) converter and the active filter type which is used the high frequency switching and the sinusoidal wave formed input current. In this type, there are many problem as a low efficiency, increased the noise, the high leakage current and cost up by the high frequency switching. For improve this problems, the partial resonan method is used on the booster inducter and lossles snubber condenser. This method decreased the distortion factor has lower harmonic components than the hard switching and there is no switching loss by the ZCS(Zero Current Switching) at switch turn-on and the ZVS(Zero Voltage Swithcing) at switch turn-off

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권12호
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• pp.686-691
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• 1999

In a switching power supply, the high frequency switching makes the passive components small, but the losses and the stresses of switches are increased by the switching frequency. Therefore, zero crossing technology using resonant is used to improve defect in high switching. In generally, zero crossing switching consists of Zero Current Switching(ZCS) and Zero Voltage Switching(ZVS). This paper proposes A Buck ZC-ZVS Converter with Reduced Conduction Losses. Comparing with a conventional Buck ZC-ZVS Converter, the proposed converter operates with the smaller rated power. This is achieved by changing the auxiliary switch position, which reduces its rating power. Simulation results using Pspice program about test circuit with rated 160W(30V, 5.3A) at 30kHz and experiment result under same condition were described in the paper.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.256-260
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• 1997

To achieve high efficiency in high power and high frequency applications, reduction of switching losses and noise is very important. In this paper, an improved soft switching forward converter is proposed. The proposed converter is constructed by using non-dissipative snubbers in parallel with the main switch and output diode of the conventional forward converter. Due to the use of the non-dissipative snubbers in the primary and secondary, the proposed converter achieves zero-voltage and zero-current switching for all switching devices without switching losses and output diode recovery losses. The complete operating principles, theoritical analysis, experimental results will be presented.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2001년도 춘계종합학술대회
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• pp.197-200
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• 2001

최근의 확산대역 통신 방식에 사용되는 주파수 합성기는 주파수 스위칭 시간이 중요한 요소가 되고 있다. FH-SS(Frequency Hopping Spread Spectrum) 송수신기에서 고속 주파수 합성기 설계는 채널 효율을 높이기 위해 매우 중요하다. 본 논문에서는 기존 PLL방식에 직접 접근 주파수 합성 (DDS) 방식을 응용하여 1 $\mu\textrm{s}$ 이하의 스위칭 시간을 갖는 고속 주파수 합성기를 설계하고, 이를 2.4GHz 대리의FH-SS 송수신기에 적용하여 시뮬레이션 결과 20% 이상의 채널 효율 개선 효과를 얻었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.379-381
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• 1994

This paper is concerned with a zero-voltage soft-switching PWM DC-DC high-pelter converter using IGBTs, which Bakes the most of the parastic LC parameters of high-voltage transformer link, for diagnostic X-Ray power generator. The converter circuit basically utilizes phase-shift pulse width modulated series resonant full-bridge PWM DC-DC high-Power converter operating at a constant frequency:20kHz. This technique brings about dramatic decreases in the switching losses of power devices and their electrical stresses as compared with the commonly-used hard-switching PWM DC-DC power converter. The high-frequency switching operation of the converters has some effective advantages, which consist in the physical reduction in size and weight and lowered acoustic noise.

• 한국철도학회논문집
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• 제15권3호
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• pp.244-250
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• 2012

본 논문에서는 차세대 고속철도 구동 인버터 시스템의 고조파로 인한 전자기적 소음을 줄이기 위해 RCF-PWM(Random Carrier Frequency Pulse Width Modulation)을 적용한 인버터 구동시스템을 개발하였다. RCF-PWM 방식은 인버터 스위칭 주파수를 전력용 반도체의 최대 스위칭 주파수와 최소 스위칭 주파수 사이에서 임의적으로 변화시키며 PWM을 수행하는 방법이다. 본 연구의 타당성을 확인하기위해서 RCF-PWM이 적용된 차세대 고속전철 시스템을 설계하여 MATLAB/Simulink 기반의 시뮬레이터를 개발하고 이를 이용하여 일정한 스위칭 주파수를 사용하는 정규적인 SVPWM 방식과 RCF-PWM 방식의 시험결과를 비교 분석하였다.