【作者】 李海山；

【导师】 李耀华；

【作者基本信息】 中国科学院研究生院（电工研究所） ， 电力电子与电力传动， 2005， 博士

【摘要】 将新型大容量开关器件、高性能的控制策略和多电平拓扑结构结合起来,是当前实现大容量电力电子变换的有效途径和发展方向。本论文以基于IGCT的三电平NPC逆变器为研究对象,重点对中压大容量三电平逆变器的PWM调制方法、最小脉宽和死区补偿、方波调制、IGCT的仿真模型和缓冲电路等方面进行系统而深入的研究。 本文详细地对SPWM调制方法和SVPWM调制方法进行了分析和比较,指出SVPWM是较适合三电平NPC逆变器的;还对这种调制方法提出了矢量优化策略,使优化后的空间电压矢量在每个PWM周期的开关状态变化次数最少,这样能够降低开关器件的工作频率,减少器件的开关损耗和延长器件的使用寿命。该调制方法成功应用在所研制的10MVA的IGCT变流器和50KVA的IGBT变流器上。 逆变器工作在低调制系数时,其输出性能受到最小脉宽和死区效应的影响,为了改善其输出性能,本文提出了一种三电平NPC逆变器最小脉宽的处理方案,它可以在调制系数较低时仍能够输出有效的PWM脉冲,提高了逆变器在低调制系数时的性能;还提出了一种三电平NPC逆变器的死区补偿方法,它不仅可以抑制死区的影响,而且还能够消除输出电压的偏离,改善逆变器的输出特性。 由于非对称性IGCT器件的最大开关频率仅为1kHz,为了使基于IGCT三电平NPC逆变器具有较高的输出频率,本文提出了一种三电平NPC逆变器的方波调制方法,该调制方法使方波在一个基波周期内有12个可控制自由度,可以改善逆变器在方波工作状态时的控制性能,并分析了方波调制下逆变器输出电压的谐波状况,计算出了谐波最小的工作区域.所提出的这种方法在50KVA的IGBT变流器得到了成功应用。 电力电子器件是构成电力电子变换器的基础,本文提出了一种适合电路仿真的IGCT器件模型,该模型主要根据IGCT的外特性建立的。运用所建立的仿真模型分析了线路参数变化对IGCT器件开关特性的影响。仿真和实验结果验证了所建模型的正确性。 依据所建立的IGCT仿真模型,分析和设计了基于IGCT的10MVA三电平NPC逆变器的缓冲电路,并通过实验进行了验证,同时给出了IGCT逆变器的设计原则;还提出了一种适合基于IGCT三电平NPC逆变器的能量可恢复缓冲电路,这种缓冲电路能够把所储存的能量完全反馈到直流侧,从而提高了逆变器的效率。更多还原

【Abstract】 The combination of new high voltage high power switching devices, advanced control (?)ategies and multilevel topology is an effective approach and tendency to make medium or high voltage and large capacity converters for the applications such as ASD, traction drive, FACT systems and so on. This paper focused research work on the three-level Neutral Point Clamped (NPC) inverter with IGCT devices, and investigated its optimum PWM technique, the minimum pulse elimination and dead-time compensation, the square wave control method, the IGCT simulation model and the snubber circuits for the 10MVA three-level NPC inverter.This paper analyzed and compared the SPWM and SVPWM control methods, and pointed out that the SVPWM was more suitable for the three-level NPC inverter because it had less harmonic components of the output line voltage of the inverter. Additionally, this paper optimized the space voltage vector pattern with the minimum transformation of the switching state in every PWM period, therefore, the switching frequency and the switching loss were reduced, and the life-time of the power electronic device was increased accordingly. The SVPWM with optimized the space voltage vector pattern was successfully used in 10MVA IGCT converter and 50KVAIGBT converter respectively.For low modular index of the output voltage, the output performance of the inverter is degraded for the existence of minimum pulse width and the dead-time effect. In order to improve the output performance of the inverter in these cases, a method for the elimination of the minimum pulse width based on SVPWM was provided, which could produce更多还原