In this article, the equivalent mechanism between nine-switch converter (NSC) and the two six-switch converters (SSCs) is explained in detail. In order to achieve the decoupling of the upper and lower ac terminals, the concept of virtual leg is proposed and the decoupling model of NSC is established based on virtual legs. In this model, the NSC is equivalent to dual constrained SSCs. Continually, the space vector modulation method of NSC is proposed based on dual constrained SSCs modulation for both common frequency and different frequency modes. In the proposed modulation method, the concept of space vector distance function (SVDF) is proposed. SVDF represents the actual switching times between any two actual working states of NSC. The closer distance between the two actual states is, the smaller the actual switching loss will be. Using the modulation method, the NSC can realize the independent control of two sets of three-phase ac voltage and achieve the same control performance as the dual SSCs. The validity of the proposed converter is verified through simulations and experiments.

中文翻译：

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基于九开关变换器与双六开关变换器等效机制的九开关变换器调制方法


在本文中，详细解释了九开关转换器（NSC）和两个六开关转换器（SSC）之间的等效机制。为了实现上下交流端的解耦，提出了虚拟支路的概念，并建立了基于虚拟支路的NSC解耦模型。在此模型中，NSC 相当于对偶约束 SSC。继续提出基于双约束SSCs调制的NSC空间矢量调制方法，适用于共频和异频模式。在所提出的调制方法中，提出了空间矢量距离函数（SVDF）的概念。 SVDF表示NSC任意两个实际工作状态之间的实际切换时间。两个实际状态之间的距离越近，实际开关损耗就越小。利用调制方法，NSC可以实现对两组三相交流电压的独立控制，并达到与双SSC相同的控制性能。通过仿真和实验验证了所提出转换器的有效性。