一种新型T型无死区三电平拓扑结构及其改进SVPWM控制算法

针对常用三电平变流器电流流经器件多而导致导通损耗大的缺点,提出一种新型T型无死区三电平拓扑结构。当输出电平为非零时,电流只流经一个开关器件,可在一定程度上减小变流器的导通损耗。该拓扑结构在输出电平上共有4种组合,其中两两电平互相配合调制实现变流器的正、负电压调制。开关管换流为电压换流方式,电平切换过程中无需加死区调制,输出波形大为改善。根据三相系统在空间矢量图中的分布特点重新分区,完成基于T型拓扑结构的改进型SVPWM控制算法。最后完成了10 kW样机试验。试验结果验证了所提变流器的特点。

A Novel T-Type Three-Level Topology for Dead-Band Time Elimination and Its Improved SVPWM

To eliminate the disadvantage of high conduction losses because the current must flow through several devices in usual converter, a novel T-type three-level converter, without dead-band time, was proposed. The current passes through only one IGBT when the output vohage is not zero ,which would reduce the conduction losses to a certain extent. There are four output levels, two of which achieve the positive or negative voltage modulation by ways of working with each other eonflictive. Dead-band time is not needed because IGBT is closed naturally by negative voltage on the switch, which would improve the wave greatly. Meanwhile, the improved control algorithms on SVPWM were proposed to the new topology,which adjusts the vector zone based on the distribution in the vector space. Finally,a 10 kW experimental prototype converter was completed, and the results demonstrate the proposed converter＇ s features.