• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2005년도 전력전자학술대회 논문집
• /
• pp.673-676
• /
• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWM inverter using PWM level to reduce THD(Total Harmonic Distortion). and we used the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2007년도 하계학술대회 논문집
• /
• pp.512-514
• /
• 2007

The number of transformers and the size of transformers in inverter using 3-phase transformer could be reduced compare with a multi-level inverter using single phase transformer. but still the 3-phase transformer inverter needs many switches. In this study, we proposed the isolated multi-level inverter using 3-phase transformers and common arm. Also, the equal-area method is used to calculate conduction angle with switching frequency equal to output fundamental frequency and it can reduce harmonics component of output voltage and switching loss. Finally, We tested multi-level inverter to clarify electric circuit and reasonableness through Matlab simulation and experiment by using prototype inverter.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2005년도 전력전자학술대회 논문집
• /
• pp.655-658
• /
• 2005

In this paper, we proposed the electric circuit using one common arm of H-Bridge Inverters to reduce the number of switching component in multi-level inverter combined with H-Bridge Inverters and Transformers. and furthermore we suggested the new multi-level PWU inverter using PWM level to reduce THD(Total Harmonic Distortion). and we used the switching method that can be same rate of usage at each transformer. Also, we tested the proposed prototype 9-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi-level PWM inverter.

• Journal of Electrical Engineering and Technology
• /
• 제2권3호
• /
• pp.373-378
• /
• 2007

Soft switching was applied to the multi-level inverter to enhance the performance of the high-intensity discharge (HID) ballast used in vehicle headlights. The electrical properties were investigated and the available modeling of ballast in steady state was calculated using mathematical methods. The result was used in analyzing the power characteristics. The modeling was confirmed by the experiment.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권7호
• /
• pp.352-360
• /
• 2003

This paper deals with a simple method in order to analyze and compare the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components becomes different according to the multi-carrier Pulse Width Modulation(PWM) techniques, the modulation index($M_i$) and the switching frequency The previous papers analyzed the harmonic characteristics from the viewpoint of the space voltage vector. Hence, the calculation of the harmonic vector becomes more difficult and complex in 4-level or over 5-level. However, the proposed method has reduced an amount of calculation and simplified the process of it, using the relationship between the reference voltage and the output phase voltage to the load neutral point. It is applied to the 5-level cascade inverter and the harmonic characteristics for each multi-carrier PWM technique are compared through the simulation.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2002년도 추계학술대회 논문집
• /
• pp.171-174
• /
• 2002

This paper deals with a novel method in order to analyze the harmonic characteristics in the multi-level inverter. Generally, the magnitude of harmonic components is different according to the carrier PWM techniques, modulation Index(Mi), and the level of multi-level inverter The previous papers analyzed the harmonic characteristics from the viewpoint of the space vector. Hence, the calculation of the harmonic vector becomes difficult and complex in 4-level or more than S-level. However, the proposed method of this paper reduced an amount of calculation and simplified the process of calculation by using the relationship between reference voltage and output phase voltage to load neutral. This paper analyzed the harmonic and it is applied to the multi-carrier PWM techniques in 5- level and other-level of cascaded inverter system.

• 전력전자학회논문지
• /
• 제11권6호
• /
• pp.520-528
• /
• 2006

동일한 변압기를 사용하는 공통암 타입의 절연형 다중레벨 인버터에서 스위칭 주파수를 저감하기 위해 새로운 위상변위제어기법을 제안 하였다. 제안된 스위칭 방식은 인버터의 각 암이 기본주파수당 한번만을 스위칭을 하는 스텝 펄스파 방식을 사용하여 동일한 스위칭 주파수를 유지할 수 있다. 제안된 스위칭 방식의 타당성을 검증하기 위해 기존의 동일변압기를 이용한 멀티레벨 인버터의 스위칭 패턴과 제안된 위상변위 제어방식을 이용한 멀티레벨 인버터의 스위칭 패턴을 시뮬레이션하고 실험을 통해 비교 하였다.

• 전력전자학회논문지
• /
• 제12권2호
• /
• pp.139-148
• /
• 2007

본 논문에서는 3상 저주파 변압기를 이용한 절연형 멀티레벨 인버터를 제안한다. 제안된 인버터는 3상 절연형 변압기를 이용함으로 비절연형 멜티레벨 인버터와 달리 단일 직류 전원을 사용할 수 있는 장점이 있으며, 기존의 단상 변압기를 이용한 3상 멀티레벨 인버터에 비하여 변압기의 수를 줄일 수 있다. 또한 출력 기본주파수와 동일한 스위칭 주파수로 동작하는 스위칭 각 제어 방식을 통하여 출력 전압의 저차 고조파 성분과 스위치 손실을 줄일 수 있었다. Matlab을 이용한 시뮬레이션 및 실험을 통하여 제안된 방식의 타당성을 검증 하였다.

• 전력전자학회논문지
• /
• 제12권5호
• /
• pp.424-431
• /
• 2007

본 논문은 발전소의 이차공기송풍기를 가변 회전수 제어하여 소내 소비 전력을 절감하고 전동기의 직입기동에 의한 스트레스를 줄이기 위하여 실증 적용된 200MW 석탄화력 발전소 순환 유동층 보일러 이차 공기 송풍기 구동용 H-브릿지 멀티레벨 인버터에 관한 것이다. H-브릿지 멀티레벨 인버터는 독립적으로 절연된 직류 부를 갖는 저전압의 단상 인버터(셀 인버터)를 다수 직렬 접속하여 고전압 3상 전압을 출력하는 Cascaded H-브릿지 전압형 인버터이다. 전력연구원은 6.6kV, 1MVA급 인버터 개발, 발전소에 설치, 보일러 점화 전/후 시험 및 계통 병입 후 부하 시험 등을 국내 최초로 성공적으로 완료하였다. 현재 200MW 석탄화력 발전소 이차 공기 송풍기 구동용 인버터는 상업 운전 중에 있다. 본 논문에서는 개발된 H-브릿지 멀티레벨 인버터, 기존 발전 설비와 신규 인버터 시스템의 인터페이스 부분에 해당하는 보일러 DCS(Distributed Control System : 분산 제어 시스템) 로직, 계통 병입 후 시운전 결과에 대하여 상세히 기술하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권10호
• /
• pp.544-554
• /
• 1999

Multi-level inverters are now receiving widespread interest form the industrial drives for high power variable speed applications. Especially, for the high power variable speed applications, a diode clamped multi-level inverter has been widely used. However, it has the inherent problem that the voltage of the link capacitors fluctuates. This paper describes a voltage control scheme effectively to suppress the DC-link potential fluctuation for a diode clamped four-level inverter. The current to flow from/into the each link capacitor is analyzed and the operation limit is obtained when a conventional SVPWM is used. To overcome the operation limit, a modified carrier-based SVPWM is proposed. Various simulation and experiment results are presented to verify the proposed voltage control scheme for DC-link voltage balancing.