This article studies a dual inverter supplied by a dc-link and a floating capacitor (FC), emerged as a promising inverter topology for motor drive applications. For this type of inverter, the voltage ratio between the dc-link and the FC can be actively controlled. This ratio design is crucial as it essentially defines both the dc-link voltage utilization and the inverter output quality. Several voltage ratios have previously been discussed to enhance the dual inverter performance, but only one aspect, either the voltage utilization or the output quality, is investigated. As a result, although one performance aspect can be improved, the other aspect has been adversely affected. In this article, a comparative study considering both aspects is carried out for all the possible voltage ratios. Based on this analysis, the optimal ratios for different inverter modulation indices are identified. This is followed by proposing a ratio selection strategy to double the voltage utilization without degrading the output quality. This strategy enables an electric drive to work at a higher maximum speed without flux weakening for a given dc-link voltage. The claimed advantages have been proved by experimental tests on an open-end windings induction motor drive.

中文翻译：

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具有浮动电容器的双逆变器的增强性能，适用于电机驱动应用

本文研究了由直流链路和浮置电容器（FC）提供的双逆变器，这种双逆变器已成为电机驱动应用中有希望的逆变器拓扑。对于这种类型的逆变器，可以主动控制直流母线和FC之间的电压比。该比率设计至关重要，因为它实质上定义了直流母线电压利用率和逆变器输出质量。先前已经讨论了几种电压比以增强双逆变器性能，但是仅研究了一个方面，即电压利用率或输出质量。结果，尽管可以改善一个性能方面，但是另一方面也受到不利影响。在本文中，针对所有可能的电压比进行了同时考虑两个方面的比较研究。根据此分析，确定了不同逆变器调制指数的最佳比率。随后提出一种比率选择策略，以在不降低输出质量的情况下使电压利用率增加一倍。这种策略使电驱动器能够以更高的最大速度工作，而对于给定的直流母线电压，磁通不会减弱。通过在开放式绕组感应电动机驱动器上的实验测试，证明了所要求保护的优点。