新型多电平Z源逆变器调制策略及并网研究

发布时间：2018-03-17 22:14

本文选题：Z源逆变器　切入点：升压单元　出处：《兰州交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：近年来,光伏与风电等新能源的开发与利用受到了广泛重视。Z源逆变器具有单级可调压特性,弥补了传统电压源型与电流源型逆变器的不足,在新能源并网领域备受青睐。传统Z源逆变器升压能力低,耐压能力差,功率低;而改进拓扑,虽然提高了升压能力,但结构复杂且多集中在两电平结构;近些年虽然有Z源三电平与五电平结构被提出,提高了功率,但升压能力没有提升。针对以上问题,提出了五种新型Z源逆变器拓扑,并研究了其调制策略与并网应用,研究内容主要包括:(1)将传统Z源两电平逆变器中的电感用升压单元代替,提出了一种新型Z源两电平逆变器电路,阐述了该拓扑的工作原理,分析了三种PWM调制与一种SVPWM调制方法,并将新型拓扑与传统型和几种改进型两电平Z源逆变器拓扑作了对比分析。(2)为简化三电平Z源逆变器拓扑和提高效率,分别提出了基于升压单元的Z源和准Z源T型三电平逆变器电路,分析了其工作原理,推理了升压能力与直通时间的关系,对比了载波同相层叠PWM与载波反相层叠PWM的调制方法。为实现准Z源T型三电平逆变器的中点电位平衡,设计了一种阶梯波加双调制波的调制策略,并将新型拓扑与传统Z源三电平二极管钳位拓扑作了对比分析。(3)为改进传统五电平逆变器拓扑,设计了一种新的T型五电平逆变器电路。为提高Z源逆变器功率等级和输出电能质量,提出Z源T型五电平逆变器拓扑和高增益Z源T型五电平逆变器拓扑,分析了新型拓扑工作原理、直通状态的插入方法以及载波同相层叠PWM策略,并将新型拓扑与传统Z源五电平二极管钳位拓扑作了对比分析。(4)针对新能源并网系统直流侧电压不稳定的问题,建立了基于新型Z源两电平逆变器的并网模型,并设计了Z源网络的参数。针对以上研究做了大量仿真实验,结果表明:新型两电平、T型三电平与T型五电平Z源逆变器均具有较强的升降压能力并降低了电容与开关器件的电压应力;T型三电平与T型五电平Z源逆变器结构简单并消除了钳位二极管损耗;双调制波加阶梯波的调制方法有效抑制了Z源T型三电平逆变器的中点电位波动;载波同相层叠PWM策略实现了T型五电平、新型Z源T型及高增益Z源T型五电平逆变器的稳定运行;基于新型两电平Z源逆变器的并网系统有效解决了分布式发电系统直流侧电压不稳定的问题。
[Abstract]:In recent years, the development and utilization has been paid attention to by.Z source inverter with single stage pressure adjustable characteristics of new energy photovoltaic and wind power etc., overcomes the shortcoming of the traditional voltage source and current source inverter, favored in the new energy grid. The inverter boost ability of traditional Z source low voltage power ability is poor. Low; and improved topology, while improving the ability of boost, but the structure is complex and more concentrated in the two level structure in recent years; although there are Z source of three level and five level structure is put forward, and improve the power, but the boost capacity did not improve. To solve the above problems, the paper introduced five new kinds of Z source inverter topology, and research the modulation strategy and network applications, the research content mainly includes: (1) the traditional inductance Z source inverter of two level instead of boosting unit, put forward a new type of circuit Z source two level inverter, expounds the working principle of the topology. Analysis, three kinds of PWM modulation and a SVPWM modulation method, and the new topology with the traditional type and several improved two level Z source inverter topology is compared. (2) to simplify the three level Z source inverter topology and improve efficiency are put forward based on boosting unit circuit Z source and Z the source T three level inverter, analyzes its working principle, the relationship between the boost ability and time through reasoning, carrier phase disposition modulation method and carrier phase PWM stacked PWM were compared. The midpoint potential balance to achieve the quasi Z source T three level inverter, designed the modulation strategy of double modulation of a ladder wave, and the new topology with traditional Z source three level diode clamped topology were analyzed. (3) in order to improve the traditional topology of five level inverter, a new circuit T five level inverter. In order to improve the design of Z source inverter power rating and The output power quality, the topology of Z source T five level inverter and high gain Z source T five level inverter, analyzes the principle of the new topology, direct insertion method and carrier phase disposition strategy of PWM state, and the new topology with traditional Z source five level diode clamped topology is compared. (4) according to the new energy grid system of DC voltage instability problems, a new Z source grid model based on two level inverter, and design parameters of Z source network. In view of the above research done a large number of simulation experiments, the results show that the new T two level, three level and five level Z T the source inverter has the strong ability of lifting pressure and reduce the voltage stress of the switches and capacitors; T three level T and five level structure of Z source inverter is simple and eliminates clamp diode loss; double modulation wave and ladder wave modulation The method can effectively restrain the fluctuation of neutral point potential Z source T three level inverter; carrier phase disposition PWM method to achieve the T five level, stable operation of the new type and high gain T Z source Z source T five level inverter; grid connected system model of two level Z source inverter effectively solves the DC Distributed power system side based on the problem of voltage instability.

【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464

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