Novel H-bridge Multi-level Inverter with DC-link Switches

Ho-Dong Sun,Min-Young Park,Jong-Hyoung Park,Heung-Geun Kim,Tae-Won Chun,Eui-Cheol Nho 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

This paper proposed a new multi-level inverter topology based on a H-bridge with two switches and two diodes connected to the DC-link. The output voltage of the proposed with a typical single phase inverter. The proposed multi-level inverter is applicable to a power conditioning system for renewable energy sources, and it can be also used as a building block of a cascaded multi-level inverter for a high voltage application. In case of conventional H-bridge type or NPC type multi-level inverter, 8 controllable switches are used to obtain a 5 level output voltage, but the proposed multi-level inverter requires only 6 controllable switches. Thus the circuit configuration is quite simple, reliable and cost-effective implementation is possible. The efficiency can be improved owing to the reduction of the switching loss. A new PWM method based on POD modulation is suggested which requires only one carrier signal. The switching sequence to make the capacitor voltage balanced is also considered. The feasibility is studied through simulation and experiment.

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

M. Ghasem Hosseini Aghdam,S. Hamid Fathi,Gevorg B. Gharehpetian 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.2

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.

멀티레벨 인버터 시스템의 전도손실과 스위칭손실 해석

김태진,강대욱,이요한,현동석 전력전자학회 2002 전력전자학회 논문지 Vol.7 No.2

The multi-level inverter system is very promising in ac drives, when both reduced harmonic contents and high power are required. In case of multi-level inverter system, the loss of switch devices cannot be analyzed by conventional methods. The reason is that the loss of each the switch device is different from one another unlike 2-level. In this paper, a simple and accurate method of computing conduction and switching loss is proposed for multi-level inverter system. The validity of the proposed method is proven for 3-level and 4-level diode clamped inverter system. 멀티레벨 인버터 시스템은 낮은 고조파 성분과 높은 전력이 요구되는 분야에 매우 효율적인 시스템이다. 멀티레벨 인버터 시스템의 경우에 스위치 소자의 손실은 기존의 방법으로는 해석 할 수 없다. 그 이유는 각 스위치 소자의 손실이 2-레벨과는 다르게 서로 같지 않기 때문이다. 본 논문에서는 멀티레벨 인버터 시스템에 대한 전도 손실과 스위칭 손실의 간단하고 정확한 방법을 제안하였다. 제안된 방법의 타당함은 3-레벨과 4-레벨 다이오드 클램프드 인버터 시스템에 대해 증명하였다.

출력전압 레벨 수와 전류정격을 고려한 PWM 다중레벨 인버터

박노식(N-S Park),서종준(J-J Seo),박성준(S-J Park),김광헌(K-H Kim),조수억(S.E. Cho),김철우(C-U Kim) 전력전자학회 2005 전력전자학술대회 논문집 Vol.- No.-

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.

계통연계형 멀티스트링 3상 3레벨 태양광 인버터의 MPPT 제어방법에 관한 연구

김진수,양오 한국반도체디스플레이기술학회 2014 반도체디스플레이기술학회지 Vol.13 No.4

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%.

A Flexible Five-level Cascaded H-bridge Inverter for Photovoltaic Gird-connected systems

Bo Sun,Fengjiang Wu,Mehdi Savaghebi,Josep M.Guerrero 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

With the rapid penetration of photovoltaic (PV) grid-connected system in industrial and commercial application, it is critical to improve the efficiency and enhance the utilization of PV power generation system. This paper proposes a flexible five-level topology based on cascaded multi-level inverter for PV grid-connected system. By adding a bidirectional switch to conventional multi-level inverter, the proposed topology transforms operating mode between two-level H-bridge inverter (HBI) and cascaded multilevel inverter (CMI) according to the variation of DC link voltage. When output voltages of PV arrays are lower, the proposed inverter works in CMI mode to widen the generation range. When output voltages of PV panels are higher, inverter works in HBI mode to increase the efficiency. Hence the system incorporate the low losses feature of HBI and low grid-connected current THD advantages of CMI. This way, a wide range output voltage operation with high efficiency can be achieved without extra DC-DC converter. Experimental results of the proposed five-level CMI are presented to validate the feasibility of the proposed topology.

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

Mohana Sundar Manoharan,Ashraf Ahmed,Jung-Won Seo,Joung-Hu Park 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

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 DCLink 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.

Design and Implementation of a Multi Level Three-Phase Inverter with Less Switches and Low Output Voltage Distortion

Mahrous E. Ahmed,Saad Mekhilef 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.4

This paper proposes and describes the design and operational principles of a three-phase three-level nine switch voltage source inverter. The proposed topology consists of three bi-directional switches inserted between the source and the full-bridge power switches of the classical three-phase inverter. As a result, a three-level output voltage waveform and a significant suppression of load harmonics contents are obtained at the inverter output. The harmonics content of the proposed multilevel inverter can be reduced by half compared with two-level inverters. A Fourier analysis of the output waveform is performed and the design is optimized to obtain the minimum total harmonic distortion. The full-bridge power switches of the classical three-phase inverter operate at the line frequency of 50㎐, while the auxiliary circuit switches operate at twice the line frequency. To validate the proposed topology, both simulation and analysis have been performed. In addition, a prototype has been designed, implemented and tested. Selected simulation and experimental results have been provided.

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 The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

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.

3상 변압기를 이용한 절연형 멀티레벨 인버터

송성근,김태진,박성준,김철우 전력전자학회 2007 전력전자학회 논문지 Vol.12 No.2

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. In this paper, we proposed the isolated multi-level inverter using 3-phase transformers. It makes possible to use a single DC power source due to employing low frequency transformers. In this inverter, the number of transformer could be reduced comparing with an exiting 3-phase multi-level inverter using single phase transformer. Also, using phase angle control method with switching frequency equal to output fundamental frequency, harmonics component of output voltage and switching losses can be reduced. Finally, we made a prototype inverter to clarify the proposed electric circuit and reasonableness of control signal.