New operation modes of modular multilevel converters with output voltage modulation significantly reducing the module capacitor requirements - II

具有输出电压调制功能的模块化多电平转换器的新操作模式显着降低了模块电容器需求 - II

• 批准号: 324166923
• 负责人: Professor Dr.-Ing. Axel Mertens
• 金额: --
• 依托单位: Institut für Antriebssysteme und Leistungselektronik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/324166923?language=en
• 关键词: New; operation; modes; modular; multilevel

In the expiring project period, a quasi-2-level (Q2L) PWM Operating mode for Modular Multilevel Converters (MMC) with controlled branch currents was validated. It enables a drastic reduction of the module capacitors to a few percent of their usual size. This is a decisive advantage for cost, volume and weight. At the same time, many advantages of MMC are retained, such as scalability, redundancy, use of low-cost low-voltage semiconductors in the modules, etc. In particular, the steps in the output voltage and the associated dv/dt are also limited to the values of a single module, which is important in electric drives with long motor cables for insulation design and the risk of bearing currents. An important disadvantage of the Q2L-MMC is the increased distortion of the output voltages and currents compared to MMC, similar to the conditions in conventional two-point inverters. This is where the proposed follow-up project starts. The concept shall be extended to quasi-n-level MMC with a low number of active levels, thus significantly reducing the output waveform distortion. In the current project, the approach with controlled branch currents could already be transferred to a quasi-3-level (Q3L) MMC which was validated in simulations. In addition, a hybrid Q3L-MMC topology with less effort, as well as the transfer of Q3L to a modular matrix multilevel converter (MMMC) have been simulated. Based on this, the aim of the proposed follow-up project is as follows. The variants mentioned need to be validated experimentally before an evaluation and comparison with existing solutions takes place. Also, the concept shall be extended and generalized to n-level converters, including validation of a Q5L operation in the laboratory. In the case of hybrid variants, in addition to the topology concepts already mentioned, another approach is attractive that has not yet been studied in detail. This new approach offers many potential advantages, even over conventional multilevel converters. As part of the proposed project, this innovative concept will also be researched and evaluated.

在即将到期的项目期间，验证了具有受控分支电流的模块化多电平变换器（MMC）的准2电平（Q2 L）PWM操作模式。它可以将模块电容器大幅减少到其通常尺寸的百分之几。这对于成本、体积和重量来说是一个决定性的优势。同时，MMC的许多优点都得到了保留，例如可扩展性、冗余性、在模块中使用低成本的低压半导体等。特别是，输出电压的阶跃和相关的dv/dt也被限制在单个模块的值内，这在具有长电机电缆的电驱动中对于绝缘设计和轴承电流的风险非常重要。与MMC相比，Q2 L-MMC的一个重要缺点是输出电压和电流的失真增加，类似于传统两点逆变器的情况。这就是拟议的后续项目的起点。该概念应扩展到具有少量有效电平的准n电平MMC，从而显著降低输出波形失真。在当前项目中，具有受控分支电流的方法已经可以转移到准3级（Q3 L）MMC，该MMC已在模拟中得到验证。此外，一个混合的Q3 L-MMC拓扑结构，以更少的努力，以及Q3 L的转移到一个模块化矩阵多电平变换器（MMMC）进行了仿真。在此基础上，拟议的后续项目的目标如下。在与现有解决方案进行评估和比较之前，需要对上述变体进行实验验证。此外，该概念应扩展和推广到n电平转换器，包括在实验室中验证Q5 L操作。在混合变量的情况下，除了已经提到的拓扑概念，另一种方法是有吸引力的，尚未详细研究。这种新的方法提供了许多潜在的优势，甚至超过传统的多电平转换器。作为拟议项目的一部分，还将对这一创新概念进行研究和评估。