本文選題：二極管鉗位式多電平變流器 + 五電平NPC/H橋變流器　； 參考：《中國礦業(yè)大學(xué)》2014年碩士論文

【摘要】：多電平變流器具有減小輸出電流、電壓諧波及降低開關(guān)器件應(yīng)力的優(yōu)點(diǎn)，其應(yīng)用越來越廣泛，脈寬調(diào)制算法是決定變流器輸出特性的關(guān)鍵因素之一。本論文分別以三相三線制二極管鉗位式多電平變流器、級(jí)聯(lián)式多電平變流器為研究對(duì)象，對(duì)其調(diào)制方法進(jìn)行詳細(xì)分析和研究，給出易于實(shí)現(xiàn)的簡化調(diào)制策略。 針對(duì)三相三線制二極管鉗位式多電平變流器，傳統(tǒng)空間矢量脈寬調(diào)制策略(SVPWM)扇區(qū)判斷繁瑣，作用時(shí)間計(jì)算復(fù)雜，本文提出二極管鉗位式三電平變流器簡化SVPWM算法，該算法的思路：基于分類算法推導(dǎo)各橋臂開關(guān)的開關(guān)時(shí)刻，歸納其特點(diǎn)，給出算法實(shí)現(xiàn)的簡化方法。算法在實(shí)現(xiàn)過程中無需扇區(qū)判斷等中間步驟，可直接根據(jù)參考電壓得出各開關(guān)的開關(guān)時(shí)刻。對(duì)三電平簡化SVPWM算法進(jìn)行仿真和實(shí)驗(yàn)驗(yàn)證，結(jié)果表明所提出的簡化調(diào)制策略能夠較準(zhǔn)確的等效參考電壓。將簡化算法推廣到五電平，與基于非正交60g h坐標(biāo)系空間矢量脈寬調(diào)制算法比較，簡化算法的運(yùn)行速度及效果均優(yōu)于后者。 控制中點(diǎn)電位平衡是制約三電平NPC（Neutral-Point Clamped）拓?fù)浣Y(jié)構(gòu)推廣和應(yīng)用的一大難題。本文在分析各矢量對(duì)變流器中點(diǎn)電位影響效果的基礎(chǔ)上，采用控制中點(diǎn)電荷的方案調(diào)節(jié)直流側(cè)中點(diǎn)電位，理論分析可知通過控制正負(fù)小矢量的作用時(shí)間能夠抵消直流側(cè)中點(diǎn)電荷，使中點(diǎn)電位達(dá)到動(dòng)態(tài)平衡。結(jié)合三電平簡化SVPWM調(diào)制策略，推導(dǎo)中點(diǎn)電位簡化控制策略，仿真結(jié)果表明采用的調(diào)制策略能夠控制中點(diǎn)電位在允許范圍內(nèi)�？紤]死區(qū)效應(yīng)，分析在不同電流極性情況下，變流器理想輸出電壓與開關(guān)狀態(tài)的關(guān)系，在此基礎(chǔ)上給出死區(qū)優(yōu)化補(bǔ)償策略，仿真驗(yàn)證了該死區(qū)補(bǔ)償策略的有效性。 五電平NPC/H橋變流器相比于鉗位式多電平變流器，鉗位二極管少，不存在均壓問題，論文研究該拓?fù)涞膿Q流方式，建立多電平變流器的數(shù)學(xué)模型，以此為理論基礎(chǔ)，分析其調(diào)制策略。對(duì)比鉗位式五電平NPC拓?fù)�，根�?jù)變流器輸出電平與開關(guān)狀態(tài)的對(duì)應(yīng)關(guān)系，在分析和確定五電平NPC/H橋各開關(guān)器件編號(hào)的前提下，應(yīng)用五電平簡化SVPWM實(shí)現(xiàn)其調(diào)制；結(jié)合載波相移(SPWM)與三電平簡化SVPWM算法，令兩個(gè)三角載波相位相差π/2，，將五電平NPC/H橋變流器的調(diào)制轉(zhuǎn)化為三電平變流器的調(diào)制。仿真驗(yàn)證兩種調(diào)制方法均能實(shí)現(xiàn)五電平NPC/H橋變流器的調(diào)制，且載波相移調(diào)制策略的運(yùn)行速度與仿真效果優(yōu)于五電平簡化SVPWM控制方法，實(shí)驗(yàn)驗(yàn)證了載波相移與三電平簡化SVPWM相結(jié)合調(diào)制策略的有效性。
[Abstract]:Multilevel converter has the advantages of reducing the output current, voltage harmonics and reducing the stress of switching devices. The pulse width modulation algorithm is one of the key factors to determine the output characteristics of the converter. In this paper, three-phase three-wire diode clamped multilevel converters and cascaded multilevel converters are taken as the research objects. The modulation methods are analyzed and studied in detail, and a simplified modulation strategy is given. Aiming at three-phase three-wire diode clamped multilevel converter, the traditional space vector pulse width modulation (SVPWM) sector judgment is tedious and the calculation of operation time is complicated. In this paper, a simplified SVPWM algorithm for diode clamped three-level converter is proposed. The idea of this algorithm: based on the classification algorithm, the switching time of each arm switch is deduced, the characteristics of the switch are summarized, and the simplified method of the algorithm implementation is given. In the process of implementation, the switching time of each switch can be obtained directly from the reference voltage without the intermediate steps such as sector judgment. The simulation and experimental results of the three-level simplified SVPWM algorithm show that the proposed simplified modulation strategy can provide an accurate equivalent reference voltage. The simplified algorithm is extended to five levels. Compared with the space vector pulse width modulation algorithm based on non-orthogonal 60g h coordinate system, the speed and effect of the simplified algorithm are better than that of the latter. Controlling neutral-point potential balance is a difficult problem that restricts the promotion and application of three-level NPC (Neutral-Point Clamped) topology. Based on the analysis of the effect of each vector on the midpoint potential of the converter, the midpoint potential at the DC side is regulated by the scheme of controlling the mid-point charge. Theoretical analysis shows that the midpoint charge can be offset by controlling the action time of positive and negative small vectors, and the midpoint potential can reach dynamic equilibrium. Combined with the three-level simplified SVPWM modulation strategy, the simplified neutral point potential control strategy is derived. The simulation results show that the proposed modulation strategy can control the neutral point potential within the allowable range. Considering the dead-time effect, the relationship between the ideal output voltage and the switching state of the converter under different current polarity is analyzed. On the basis of this, the dead-time optimal compensation strategy is given, and the effectiveness of the damned zone compensation strategy is verified by simulation. Compared with the clamped multilevel converter, the five-level NPC-H bridge converter has fewer clamping diodes and no voltage-sharing problem. This paper studies the converter mode of the topology and establishes the mathematical model of the multilevel converter, which is the theoretical basis. The modulation strategy is analyzed. Compared with the clamped five-level NPC topology, according to the corresponding relationship between the output level of the converter and the switching state, and under the premise of analyzing and determining the switching device numbers of the five-level NPC-H bridge, the five-level simplified SVPWM is used to realize the modulation. Combining the carrier phase shift (SPWM) algorithm with the three-level simplified SVPWM algorithm, the phase difference between the two triangular carriers is 蟺 / 2. The modulation of the five-level NPC-H bridge converter is converted into the modulation of the three-level converter. The simulation results show that both of the two modulation methods can realize the modulation of five-level NPC-H bridge converter, and the speed and simulation result of the carrier phase-shift modulation strategy are better than that of the five-level simplified SVPWM control method. The effectiveness of the modulation strategy combined with carrier phase shift and three-level simplified SVPWM is verified by experiments.
【學(xué)位授予單位】：中國礦業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TM46

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