一种新型混合级联逆变器的研究

【作者】 黄庆利；

【导师】 桂武鸣；

【作者基本信息】 中南大学 ， 电力电子与电力传动， 2008， 硕士

【摘要】 在大功率应用领域,多电平逆变器具有许多独特的优点,如不需要器件串联就可以实现高电压等级的输出、输出电压du/dt小、输出电压谐波含量少,因此多电平逆变器在电力系统以及大功率交流传动领域受到极大的重视。目前常见的多电平逆变器主要有三种:二极管箝位式、电容箝位式和级联式。级联逆变器的每一相由多个单相全桥逆变器串联而成,因此级联逆变器的调制,控制以及器件的保护都是模块化的,易于逆变器的生产、应用和扩展。但是级联逆变器需要为每个单相逆变单元提供一个独立的直流源,因此当逆变器输出电压的电平数较多时需要大量的独立直流源,这是级联逆变器的主要缺点,它限制了级联逆变器的应用范围。为了解决这个问题,文中提出了一种新型混合级联逆变器。这种新型混合级联逆变器通过提高直流源的利用率,从而达到减少直流源数的目的。本文首先从单相逆变器的工作原理入手,针对单相逆变器存在的问题导出新型混合级联逆变器的工作原理并运用MATLAB/simulink进行仿真,然后再扩展到三相混合级联逆变器。从仿真结果证实了新型混合级联逆变器可以实现三相五电平、七电平和十一电平输出,而且控制简单有效。由于新型混合级联逆变器省去了一半或一半以上的直流源,应此系统得到了简化,可靠性得到了提高。更多还原

【Abstract】 For high-power applications, multilevel inverter structures have the particular advantage, such as high level output voltage without series strings of switching devices, lower du/dt and reduction in output voltage harmonics, so great emphasis has been putting on it in the application of power system and high-capacity AC drive applications. Nowadays, there are three prominent multilevel topologies, diode-clamped multilevel inverter, capacitor-clamped multilevel inverter and cascaded multilevel inverter. The cascaded inerter uses series strings of single-phase full-bridge inverters to construct multilevel phase legs. This topology that the modulation, control, and protection requirements of each bridge are modular leads to advantages in terms of manufacturing and flexibility of application. However each single-phase inverter requires its own isolated dc supply. This complexity has generally restricted cascaded inverters to the higher power range. In this paper, a new hybrid cascaded multilevel inverter is proposed to solve cascaded inverter’s primary disadvantage, a number of separate dc sources required. At first, the concept of the new hybrid cascaded multilevel inverter is derived by analysis single phase inverter’s theory, and then a series of diagram and waveform based on MATLAB/simulink are given for reference. This new hybrid cascaded multilevel inverter has much advantage, such as simple topology, five or seven level output voltage, only one or two isolated dc source required and high dc source’s utilization ratio. The improved new hybrid cascade multilevel inverter needs one isolated dc source for each phase, but the output voltage is of seven or eleven steps. This new hybrid cascaded multilevel inverter requires half of isolated dc source at most, so the inverter system is simple, and the reliability is enhanced.更多还原