基于IGCT的高压大功率三电平整流器的关键技术研究

Because high-voltage high-power three-level rectifiers based on IGCT can realize energy's bidirectional flow and power factor's regulation, they have found more and more applications in the high-performance drive areas such as traction drive and mine hoisting, etc. The existing space vector modulation (SVM) techniques have not considered the minimum pulse width limitation, self-balancing ability, neutral point voltage-balancing control, and multi-sampling techniques comprehensively. At the same time, the conventional neutral point voltage-balancing control methods can not obtain satisfactory effectiveness when the rectifier is under no-load and light-load conditions. What mentioned above are the two key difficulties impeding rectifiers' reliable operation. This application wants to do extensive research on the optimized SVM under minimum pulse width limitation, and on the neutral point voltage-balancing control methods for rectifiers under no-load and light-load conditions. To explore all possible dividing modes for space vector diagram and all possible switching sequences so as to get optimized SVM under the minimum pulse width limitation, which is beneficial to neutral point voltage-balancing control, can minimize the output voltage harmonics, and has low switching frequency. To search the neutral point voltage-balancing control methods which are not dependent on current polarity judgement, and to do some research on current prediction techiniques and on the synchronized SVM in order to improve the neutral point voltage-balancing control ability under the no-load and light-load conditions,meanwhile to establish the neutral point voltage-balancing areas' theoretical boundary with considering the minimum pulse width limitation. So the application has important scientific meaning and engineering value.

基于IGCT的高压大功率三电平整流器由于能实现能量的双向流动且功率因数可调，已经越来越多地应用在列车牵引、矿井提升等高性能传动场合。现存的空间矢量调制(SVM)技术未能综合考虑最小脉宽限制、自平衡能力、中点电压平衡控制、多采样技术等多方面的因素；同时传统中点电压平衡控制在整流器空载和轻载时无法达到满意的控制效果，这是限制三电平整流器可靠运行的两个关键技术难题。本申请拟对最小脉宽限制下的优化SVM，以及空轻载条件下的中点电压平衡控制进行深入研究。发掘所有可能的区域划分方式及所有可能的开关顺序组合，寻求以最小脉宽限制为约束条件，以有利于中点电压平衡、输出电压谐波含量小、开关频率低为目标的优化SVM。探索不依赖于电流极性判断的中点电压平衡控制方法，并研究电流预测及同步SVM技术以提高空轻载时中点电压的平衡控制能力；建立最小脉宽限制下中点电压平衡的理论极限。项目具有重要科学研究意义和工程技术价值。

基于IGCT的高压大功率三电平整流器由于能实现能量的双向流动且功率因数可调，已经越来越多地应用在列车牵引、矿井提升、风力发电、电能质量治理等众多场合。研究高压大功率三电平整流器的优化调制技术和高性能中点电压平衡控制算法从而保证其可靠良好运行，具有重要的科学研究意义和工程技术价值。本项目针对低开关频率时经典空间矢量调制(SVM)技术存在的问题，提出了一种满足最小脉宽限制、具备中点电压平衡控制能力、适用于多采样系统以及具有低开关损耗等性能的优化SVM。解决了多采样系统中的NP/PN直接跳变问题、最小脉宽最优处理问题以及降低器件开关损耗等问题。针对空轻载条件下现有中点电压平衡控制失效的问题，提出一种基于电流预测、采样点位置控制以及优化SVM的中点电压平衡控制算法，解决了空载和轻载条件下的中点电压平衡控制问题。同时提出了一种基于虚拟空间矢量(SVVM)的改进中点电压平衡控制方法，提高了中点电压平衡控制的稳态和动态性能。另外该项目还研究了三电平整流器的中点电压平衡极限，并提出了一种克服这种局限的实际应用方法。通过上述研究，本项目实现了高压大功率三电平整流器的良好稳定运行，相关研究成果已经成功应用在7.5MVA IGCT背靠背三电平变流器中。