中压混合型模块化多电平变换器的载波移相调制策略

Phase-shifted carrier modulation strategy for medium voltage hybrid modular multilevel converters

由于半桥子模块与全桥子模块的载波移相调制策略不同,两者混合而成的模块化多电平变换器(modular multilevel converter, MMC)不能直接沿用原来的调制策略;在船舶中压直流电力系统中,由于变换器模块数较少,交流输出电压的波形质量相对较差。基于上述原因,通过载波相位角的合理配置,提出一种改进型载波移相调制策略。该策略不仅能够增加交流输出电压的电平数,而且不局限于某种特定的拓扑结构。通过仿真验证其有效性和通用性,验证结果显示它是一种适用于中压混合型MMC的通用调制策略。

The hybrid modular multilevel converter (MMC) composed of the half bridge and full bridge sub-modules can not directly use the original modulation strategy because of the difference of phase-shifted carrier modulation strategy of the two sub-modules;the quality of the AC output voltage waveform is relatively poor due to the small number of converter modules in the medium voltage DC power system for ships. To solve the above problems, an improved phase-shifted carrier modulation strategy is proposed through the reasonable allocation of carrier phase angle. This strategy not only can increase the level number of AC output voltage, but also is not limited to a specific topological structure. The validity and generality of this strategy are verified by simulation, and the verification result shows that this is a general modulation strategy suitable for a medium voltage hybrid MMC.