• Title, Summary, Keyword: Multi-level inverter

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Power Conditioning for a Small-Scale PV System with Charge-Balancing Integrated Micro-Inverter

  • Manoharan, Mohana Sundar;Ahmed, Ashraf;Seo, Jung-Won;Park, Joung-Hu
    • Journal of Power Electronics
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    • v.15 no.5
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    • pp.1318-1328
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    • 2015
  • The photovoltaic (PV) power conditioning system for small-scale applications has gained significant interest in the past few decades. However, the standalone mode of operation has been rarely approached. This paper presents a two-stage multi-level micro-inverter topology that considers the different operation modes. A multi-output flyback converter provides both the DC-Link voltage balancing for the multi-level inverter side and maximum power point tracking control in grid connection mode in the PV stage. A modified H-bridge multi-level inverter topology is included for the AC output stage. The multi-level inverter lowers the total harmonic distortion and overall ratings of the power semiconductor switches. The proposed micro-inverter topology can help to decrease the size and cost of the PV system. Transient analysis and controller design of this micro-inverter have been proposed for stand-alone and grid-connected modes. Finally, the system performance was verified using a 120 W hardware prototype.

A Study on the MPPT Control Method for Grid-connected Multi-String Three-Phase Three-Level PV Inverter (계통연계형 멀티스트링 3상 3레벨 태양광 인버터의 MPPT 제어방법에 관한 연구)

  • Kim, Jinsoo;Yang, Oh
    • Journal of the Semiconductor & Display Technology
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    • v.13 no.4
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    • pp.43-48
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    • 2014
  • Two-level inverter has some disadvantages like high harmonics contained in the output current, efficiency limit and stress to switching device as IGBT and FET. Many researches have reported multi-level inverter to complement two-level inverter of problems. In this paper, we suggest MPPT algorithm of multi-string three-level solar inverter that considered nowadays. We added midpoint controller in order to implement the MPPT algorithm because the three-level inverter has to need midpoint controller and procured the stability of direct current link. We verify the superiority of multi-string T-Type inverter and the algorithm we suggested with solar irradiance variation experiment and MPPT efficiency measurement. The MPPT efficiency was confirmed with a high efficiency more than 99.97%.

Multi-level PWM Inverter Considering the number of Output Voltage level and Current rating (출력전압 레벨 수와 전류정격을 고려한 PWM 다중레벨 인버터)

  • Park, N.S.;Seo, J.J.;Park, S.J.;Kim, K.H.;Cho, S.E.;Kim, C.U.
    • Proceedings of the KIPE Conference
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    • pp.659-662
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    • 2005
  • In this paper, we proposed the novel hybrid multi-level inverter using combination of the output voltage of transformers to reduce the THD(Total Harmonic Distortion) and improve the waveform of output voltage. The proposed multi-level inverter used the output of transformer which is 1times, 2times, 4times of input of the transformers. So we increased the output voltage from the reduce the number of switching component and transformer. Also, we tested the proposed prototype 15-level inverter to clarify the proposed electric circuit and reasonableness of control signal for the proposed multi -level PWM inverter.

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A Novel Multi-Level Inverter Configuration for High Voltage Conversion System

  • Suh, Bum-Seok;Lee, Yo-Han;Hyun, Dong-Seok
    • Journal of Electrical Engineering and information Science
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    • v.1 no.2
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    • pp.109-118
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    • 1996
  • This paper deals with a new multi-level high voltage source inverter with GTO Thyristors. Recently, a multi-level approach seems to be the best suited for implementing high voltage conversion systems because it leads to harmonic reduction and deals with safe high power conversion systems independent of the dynamic switching characteristics of each power semiconductor device. A conventional multi-level inverter has some problems; voltage unbalance between DC-link capacitors and larger blocking voltage across the inner switching devices. To solve these problems, the novel multi-level inverter structure is proposed.

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A Study on the Multi-level PV-PCS Using Cascade 3-Phase Transformer (직렬형 3상 변압기를 이용한 다중레벨 PV-PCS)

  • Kim, Ki-Seon;Song, Sung-Geun;Cho, Su-Eog;Choi, Joon-Ho;Kim, Kwang-Heon;Park, Sung-Jun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.12
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    • pp.2359-2369
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    • 2009
  • The study on the multi-level inverter has been increasingly progressing to reduce the switching loss and improve the THD of output current in photovoltaic inverter. Recently, the main topics of multi-level inverter are to reduce the number of devices maintaining the power quality. Therefore, the novel topology was proposed for these problem which is composed of the isolated H-bridge multi-level inverter using the three phase low frequency transformer. The proposed multi-level inverter may not be need for a independent DC power, diode and capacitor. Specially, It has a advantage in generating high voltage source. The proposed approach is verified through simulation and experiment.

Harmonic Optimization Techniques in Multi-Level Voltage-Source Inverter with Unequal DC Sources

  • Aghdam, M. Ghasem Hosseini;Fathi, S. Hamid;Gharehpetian, Gevorg B.
    • Journal of Power Electronics
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    • v.8 no.2
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    • pp.171-180
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    • 2008
  • One of the major problems in electric power quality is the harmonic contents. There are several methods of indicating the quantity of harmonic contents. The most widely used measure is the total harmonic distortion (THD). Various switching techniques have been used in static converters to reduce the output harmonic content. This paper presents and compares the two harmonic optimization techniques, known as optimal minimization of the total harmonic distortion (OMTHD) technique and optimized harmonic stepped-waveform (OHSW) technique used in multi-level inverters with unequal dc sources. Both techniques are very effective and efficient for improving the quality of the inverter output voltage. First, we describe briefly the cascaded H-bridge multi-level inverter structure. Then, we present the switching algorithm for the inverter based on OHSW and OMTHD techniques. Finally, the results obtained for the two techniques are analyzed and compared. The results verify the effectiveness of the both techniques in multi-level voltage-source inverter with non-equal dc sources, clarifying the advantages of each technique.

A New Simplified Vector Control For A High Performance Common-Arm IHCML Inverter (고성능 공통암 IHCML 인버터를 위한 새로운 벡터 제어 방식)

  • Song, Sung-Geun;Park, Sung-Jun;Nam, Hae-Kon;Kim, Kwang-Heon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.6
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    • pp.1071-1079
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    • 2007
  • In this paper, a novel space vector control method for isolated multi-level inverter using 3-phase low frequency transformers is proposed. This method is based on the simplification of the space-vector diagram of a five-level inverter using calculated table into fully programming method. The execution time of the proposed method is about same as that of the method using calculated table. Also, the proposed method is easily applied to other case level inverter. We applied this method into the 3-phase IHCML inverter using common arm. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformers could be reduced compare with an exiting 3-phase multi-level inverter using single phase transformer. In addition, this method generates very low harmonic distortion operation with nearly fundamental switching frequency. Finally, We tested multi-level inverter to clarify electric circuit and reasonableness through Matlab simulation and experiment by using prototype inverter.

Simulation based Comparative Loss Analysis and Output Characteristic for 25MW Class of High Power Multi-level Inverters (25MW급 대용량 멀티레벨 인버터의 시뮬레이션 기반 손실해석과 출력특성 비교 분석)

  • Kim, I-Gim;Park, Chan-Bae;Baek, Jei-Hoon;Kwak, Sang-Shin
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.4
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    • pp.337-343
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    • 2015
  • The multi-level inverters are highly efficient for high-power and medium-voltage AC driving applications, such as high-speed railway systems and renewable energy resources, because such inverters generate lower total harmonic distortion (THD) and electromagnetic interface (EMI). Lower switching stress occurs on switching devices compared with conventional two-level inverters. Depending on the multi-level inverter topology, the required components and number of switching devices are different, influencing the overall efficiency. Comparative studies of multi-level inverters based on loss analysis and output characteristic are necessary to apply multi-level inverters in high-power AC conversion systems. This paper proposes a theoretical loss analysis method based on piecewise linearization of characteristic curves of power semiconductor devices as well as loss analysis and output performance comparison of five-level neutral-point clamped, flying capacitor inverters, and high-level cascaded H-bridge multi-level inverters.

3-Phase Transformer Isolated Multi-level Inverter Using Common Arm (공통암을 이용한 3상 변압기 절연 멀티레벨 인버터)

  • Song, Sung-Geun;Park, Sung-Jun;Kim, Dong-Ok;Lim, Young-Cheol;Kim, Kwang-Heon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.12 no.2
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    • pp.149-156
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    • 2007
  • The number of transformer and the size of transformer 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, in this paper. Also, using phase angle control method with switching frequency equal to output fundamental frequency, harmonics component of output voltage and switching loss can be reduced. Finally, We tested multi-level inverter to clarify electric circuit md reasonableness through Matlab simulation and experiment by using prototype inverter.

A New Multilevel Inverter of H-bridge Topology using Bidirection Switch (양방향 스위치를 이용한 H-bridge 구조의 새로운 멀티레벨 인버터)

  • Lee, Sang-Hyeok;Kang, Seong-Gu;Lee, Tae-Won;Hur, Min-Ho;Park, Sung-Jun
    • The Transactions of the Korean Institute of Power Electronics
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    • v.17 no.4
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    • pp.291-297
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    • 2012
  • Recently, Switching devices become cheaper, depending on the multi-level inverters are considered as the power-conversion systems for high-power and power-quality demanding applications. The multi-level inverters can reduce the THD(Total Harmonic Distortion) as the output which is similar sinusoidal waveform by synthesizing several capacitor DC voltages. However it has some disadvantages such as increased number of components, complex PWM control method. Therefore, this paper is proposed the new multi-level inverter topology using an new H-bridge output stage with a bidirectional auxiliary switch. The proposed topology is the 4-level 3-phase PWM inverter with less switching part than conventional multi-level inverters and reactive power control possible. In order to understand the new multi-level inverter, topology analysis and switching patterns and modes according to the current loop are described in this paper. The proposed multi-level inverter topology is validated through PSIM simulation and the experimental results are provided from a prototype.