本文選題：T型三電平　切入點(diǎn)：非隔離　出處：《燕山大學(xué)》2015年碩士論文

【摘要】：在快速增長的光伏應(yīng)用市場(chǎng)中,DC/AC逆變器作為光伏并網(wǎng)系統(tǒng)的重要組成部分,其開發(fā)與研究備受世界各國學(xué)者的關(guān)注。三電平逆變器因其輸出電能質(zhì)量高、輸出容量大等優(yōu)點(diǎn),廣泛應(yīng)用于新能源發(fā)電領(lǐng)域。在眾多三電平拓?fù)潆娐分?T型三電平拓?fù)湓诮鼛啄甑玫搅丝焖侔l(fā)展,該拓?fù)涫且环N改進(jìn)的中點(diǎn)鉗位(Neutral Point Clamped,NPC)型三電平拓?fù)?解決了傳統(tǒng)二極管中點(diǎn)鉗位型拓?fù)浯嬖诘钠骷^多、損耗分布不均等問題。因此,本文以三相T型三電平逆變器為基礎(chǔ)展開研究。首先,本文詳細(xì)分析了三相T型三電平逆變器的工作原理和換流過程,在此基礎(chǔ)上,利用器件的損耗特征參數(shù)對(duì)逆變器的開關(guān)損耗和通態(tài)損耗進(jìn)行了計(jì)算,并介紹了三電平逆變器空間矢量脈寬調(diào)制(Space Vector Pulse Width Modulation,SVPWM)方法的基本原理和實(shí)現(xiàn)方法。其次,針對(duì)非隔離型三相T型三電平逆變器中存在共模電流的問題,建立了系統(tǒng)共模等效模型,對(duì)影響共模電流的因素進(jìn)行了分析。本文采用了兩種基于傳統(tǒng)三電平SVPWM調(diào)制方式的改進(jìn)方法,通過對(duì)開關(guān)序列和基本矢量的合理選取及排序,使系統(tǒng)共模電壓減小,從而實(shí)現(xiàn)共模電流的抑制,并通過仿真驗(yàn)證了其有效性。再次,針對(duì)三相T型三電平逆變器中點(diǎn)電位不平衡的問題,分析了基本矢量對(duì)中點(diǎn)電位產(chǎn)生的影響,總結(jié)出造成中點(diǎn)電位不平衡的主要原因。在共模電流抑制方法的基礎(chǔ)上,根據(jù)正負(fù)小矢量對(duì)中點(diǎn)電位的不同影響,得到了一種基于SVPWM的中點(diǎn)電位平衡控制方法,并給出了其詳細(xì)的實(shí)現(xiàn)步驟和仿真結(jié)果。最后,搭建了以TMS320F28335 DSP為控制核心的三相T型三電平并網(wǎng)逆變器系統(tǒng)平臺(tái),并對(duì)系統(tǒng)的軟硬件設(shè)計(jì)作了介紹。在該平臺(tái)上對(duì)改進(jìn)型調(diào)制策略進(jìn)行了實(shí)驗(yàn)研究,實(shí)驗(yàn)結(jié)果驗(yàn)證了理論分析的正確性和可行性。
[Abstract]:As an important part of photovoltaic grid-connected system, the development and research of DC / AC inverter has attracted the attention of scholars all over the world in the rapidly growing market of photovoltaic applications.Three-level inverter is widely used in the field of new energy generation because of its high output power quality and large output capacity.In recent years, the T-type three-level topology has been developed rapidly in many three-level topology circuits. It is an improved Neutral Point Clamped-NPC-type three-level topology, which solves the problem that there are too many devices in the traditional diode neutral-point clamping topology.The problem of uneven distribution of loss.Therefore, this paper is based on three-phase T-type three-level inverter.Firstly, the principle and commutation process of three-phase T-type three-level inverter are analyzed in detail. On the basis of this, the switching loss and on-state loss of the inverter are calculated by using the loss characteristic parameters of the device.The basic principle and implementation method of Space Vector Pulse Width Modulation (SVPWM) method for three-level inverter are also introduced.Secondly, aiming at the problem of common mode current in unisolated three-phase T type three-level inverter, the common mode equivalent model of the system is established, and the factors influencing the common-mode current are analyzed.In this paper, two improved methods based on traditional three-level SVPWM modulation are adopted. The common mode voltage is reduced and the common mode current is suppressed by reasonably selecting and ordering the switch sequence and the basic vector.The effectiveness of the method is verified by simulation.Thirdly, aiming at the unbalance of neutral point potential in three-phase T type three-level inverter, the influence of basic vector on neutral point potential is analyzed, and the main causes of neutral point potential imbalance are summarized.On the basis of common mode current suppression method, according to the different effects of positive and negative small vectors on midpoint potential, a neutral point potential balance control method based on SVPWM is presented, and its detailed implementation steps and simulation results are given.Finally, a three-phase T type three-level grid-connected inverter platform with TMS320F28335 DSP as the control core is built, and the software and hardware design of the system is introduced.Experimental research on the improved modulation strategy is carried out on this platform, and the experimental results verify the correctness and feasibility of the theoretical analysis.
【學(xué)位授予單位】：燕山大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TM464

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本文編號(hào)：1724830