• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 추계학술대회 논문집 학회본부
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• pp.500-504
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• 1997

Current source inverter drives of auto sequentially commutated type are very popular in high power applications, because of simple power circuit configuration with four quadrant operation. But the six-step current output create harmonic problems and the input power factor of such a drive is not always good. In this respect pulse width modulated drives using gate turn off thyristors ( GTO ) are finding application, especially in traction drives. However the switching and snubber loses of a GTO do not permit the inverter switching frequency go beyond a few hundred hertz.This will again introduce low frequency harmonic problems. Multi level inverters of the 3-level and 5-level can be considered as an alternative to overcome the low switching frequency harmonic problem of the 2-level GTO inverters. But with multi level inverters the complexity of the power circuit increases. In this paper a combination of multi level ( 2-level and 3-level ) inverters and multi phase induction motor ( 3-phase and 6-phase) configurations are presented for high power VSI drives for traction applications with reduced inverter switching frequency requirements coupled with reduced voltage rating for the power switch.

• 전력전자학회논문지
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• 제4권6호
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• pp.547-553
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• 1999

본 논문에서는 기존의 12-스텝 인버터에 간단한 보조회로를 추가하여 24-스텝(또는 36-스텝)의 출력파형을 갖는 새로운 방식의 이중접속 멀티스텝 인버터를 제안한다. 제안한 인버터의 보조회로는 두 개의 전압분할용 커패시터, 두 개의 스위칭소자와 저용량의 단권변압기로 구성된다. 이 보조회로의 동작으로 24-스텝의 입·출력 파형을 얻을 수 있으며 한 개의 양방향 스위칭 소자를 추가하면 36-스텝의 파형을 얻게된다. 스위칭 함수를 이용한 전압 및 전류의 분석을 통하여 설계에 필요한 최적의 파라미터를 설정하였다. 제안한 인버터는 PWM방식을 사용할 수 없는 중용량의 SVC등에 적용하면 효과적이다. 본 방식의 타당성을 실험 및 시뮬레이션을 통하여 입증하였다.

• 전력전자학회논문지
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• 제11권3호
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• pp.209-215
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• 2006

본 논문에서는 전압원 인버터의 출력전압 파형을 개선하여 PWM방식을 사용할 수 없는 중 대용량급 모터드라이버 및 UPS, STATCOM, SVC등에 적용하기 위한 새로운 3상 전압원 24-스텝 인버터를 제안한다 보조회로로서 사용한 컨버터로 리플전압을 발생시키고 이를 기존의 12-스텝 인버터에 주입하는데 한대의 링크를 사용하면 12-스텝 동작이 24-스텝으로 전환되며 보조 변압기의 1차 권선을 2N(N=1,2,3...)으로 늘리면 12M-스텝(M=2,3,4..)으로 전환된다. 본 방식의 타당성을 실험 및 시뮬레이션을 통하여 입증하였다.

• 전기학회논문지
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• 제67권7호
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• pp.846-853
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• 2018

In this paper, an improved model predictive control (MPC) method is proposed, which reduces the amount of calculations caused by the increased number of candidate voltage vectors with the increased voltage level in multi-level inverters. When the conventional MPC method is used for multi-level inverters, all candidate voltage vectors are considered to predict the next-step current value. However, in the case that the sampling time is short, increased voltage level makes it difficult to consider the all candidate voltage vectors. In this paper, the improved MPC method which can get a fast transient response is proposed with a small amount of the computation by adding new candidate voltage vectors that are set to find the optimal vector. As a result, the proposed method shows faster transient response than the method that considers the adjacent vectors and reduces the computational burden compared to the method that considers the whole voltage vector. the performance of the proposed method is verified through simulations and experiments.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 정기총회 및 추계학술대회 논문집
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• pp.2383-2388
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• 2011

LSMs are installed under girders along the long track. In order to improve the efficiency of the LSM, long stator LSM should be divided into the specified length and the propulsion inverters should have the system topology to generate high voltage and current for LSMs. This paper presents a system topology with two-step inverter in order to generate high voltage in inverter. A LSM propulsion system is developed and implemented in Maltab/Simulink. A system model of the two-step Inverter is applied to developed model. This paper demonstrates through simulation, advantages of multi-step inverter. The conclusions can serve the design of LSM propulsion system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1258-1259
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• 2011

LSMs are installed under girders along the long track. In order to improve the efficiency of the LSM, long stator LSM should be divided into the specified length and the propulsion inverters should have the system topology to generate high voltage and current for LSMs. This paper presents a system topology with two-step inverter in order to generate high voltage in inverter. A LSM propulsion system is developed and implemented in Maltab/Simulink. A system model of the two-step Inverter is applied to developed model. This paper demonstrates through simulation, advantages of multi-step inverter. The conclusions can serve the design of LSM propulsion system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 기술교육위원회 창립총회 및 학술대회 의료기기전시회
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• pp.19-22
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• 2001

For stabilization and improving power factor in the power lines, various Static Var Compensators(SVC) have been considered to be installed and partly applicated already. With all these merits of the SVC, it stil has demerits, principally evoking harmonic problems. So far, many harmonic reduction type inverters have been used in various parts. In this paper, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control. The theoretical analysis on this system was confirmed through the computer simulation and the experiments.