级联型逆变器故障状况下的调制重构  

Modulation Reconfiguration of Cascaded Multilevel Inverters Under Fault Condition

作　　者：倪喜军[1] 赵剑锋[1] 曹武[1] 孙轲[1] 黄华[1] 

机构地区：[1]东南大学电气工程学院,江苏省南京市210096

出　　处：《中国电机工程学报》2010年第33期16-22,共7页Proceedings of the CSEE

基　　金："十一五"国家科技支撑计划重大项目(2007BAA12B03);江苏省科技支撑计划项目(BE2008072;BE2008123)~~

摘　　要：功率单元故障是级联型逆变器的常见问题,为维持逆变器持续运行,需旁路故障单元,同时相应调制技术也必须作调整,为此,提出一种实现比较简单的基于60°坐标的空间矢量分解调制技术。该文采用的矢量分解技术把输出电压参考矢量分解为固定形式的基矢量和降电平分解矢量的组合,其中,前者可通过查表法简单实现,后者可利用降电平后简单的矢量判断实现,因此该矢量调制方法大大简化。通过分析功率单元故障旁路后的电路特点,从降电平分解矢量的冗余矢量形式中选出一种可行的实现方法重构参考矢量,不仅使旁路后的输出电压值最大,而且调制重构也限于低电平矢量调制范围内调整,调制重构实现比较简单。实验表明,该矢量分解调制技术不仅可以使逆变器运行于正常状况,而且能保证逆变器故障降额运行时输出最大电压值。另外,虽然输出的相电压不平衡,但输出的线电压三相平衡,且线电压谐波含量比较低,是一种适用于级联型逆变器的调制方法。The failure of power cells of cascaded multilevel inverter often occurs.In order to maintain the operation,failed power cells must be bypassed and certain modulation technique also should be adjusted accordingly.This paper proposed a simple elegant solution,namely,divided space vector pulse width modulation based on 60 degree coordinates.The reference voltage vector can be divided into fixed basic vector which can be realized by table look-up and reduced-levels decomposed space vector realized by simple vector judgment.So,the space vector modulation is simplified.The circuit operation behavior after the by-passing due to the malfunction of power cell was studied,then a practical method to reconfigure the reference space vector was picked from the back-up vector belonging to those reduced-levels decomposed space vector.Consequently,the output voltage after by-passing could reach the maximum quantity,and the modulation reconfiguration is restricted within the region of low-voltage-level space vector modulation and it＇s easy to accomplish.The experimental result indicates that the divided space vector modulation method not only makes the inverter work well under normal condition,but also makes the output voltage reach the maximum quantity under fault condition.Though the phase to ground voltage is imbalance,the output phase to phase voltage is in balance,and THD is low and quite suitable for application in cascaded multilevel inverter.

关 键 词：级联型逆变器 降电平分解矢量 基矢量 旁路 调制重构 空间矢量脉宽调制 

分 类 号：TM46[电气工程—电器]