电压源三相四开关逆变器调制策略简

电压源三相四开关逆变器作为一种故障容错拓扑结构,其负载一相端点接至直流母线中点,利用2个桥臂完成对三相负载线电压的调制。然而在这种拓扑结构下,连接直流母线中点的相电流势必流经上下2只电容,造成电容电压波动。为了尽可能消除由于电容电压波动对调制输出电压造成的影响,文章从输出电压频谱入手分析了造成影响的原因,并且提出了一种新的调制策略来抵消这种波动所造成的影响。调制方案物理概念清晰,计算简单、方便、可靠,仿真和实验结果验证了分析的正确性和方案的可行性。

Analysis on Modulation Strategy of Voltage Source Four-switch Three-phase Inverter

As one kind of fault tolerance topology, with one load-phase connecting to the middle point of dc-link, voltage source four- switch three-phase inverter can generate balanced three-phase voltage by modulating the two bridge-legs. With this topology, the fluctuation will inevitably appear in the DC-link two-capacitor voltages as a result of circulation of one-phase current through the split DC-link voltage sources. To eliminate the fluctuation effect, the reasons were analyzed first from the view of the output voltage spectrum, and an analytical modulation method was then proposed, which not only shows a clear physical conception, but also easy, convenient and reliable computation. The simulation and experiment results validate the correction of analysis and feasibility of the method.