两种混合多电平变换器拓扑结构控制策略的分析

Analysis of control strategy for two hybrid multilevel converters with topology structure

提出了一种以是否共享中间直流电压源为依据的新的多电平拓扑结构分类,并给出了两种相应的拓扑结构。这两种拓扑结构结合了GTO耐压值高和IGBT开关频率快的优点,并对它们分别采用工频调制和PWM调制策略,既可以减小系统开关损耗,降低EMI,又可以提高电压等级。其中不同电压比的混合拓扑结构还可以在相同直流电压源的情况下,增加输出电压电平数量。最后对这两种拓扑结构和控制策略进行了比较和分析,同时给出了一些在实际设计中应该注意的问题。

A new classifiable method of multilevel topology, which based on whether or not sharing the DC voltage sources is given in this paper. Two relevant hybrid series-connected multilevel topologies are introduced. The topologies combining advantage of GTO and IGBT, can not only reduce switching losses and EMI, but also improve output waveforms quality. Especially, the topology which has different voltage ratios can synthesize a large number of voltage levels with the same number of series-connected inverters and, consequently, reduce the THD of the output voltage. Finally, different topologies and strategies are compared and analyzed, meanwhile some points in the application are discussed.