面向交流传动的相间耦合型MMC低频运行优化模型预测控制研究

Modular multilevel converter (MMC) is a potential topology for the high-power AC drive applications. However, the main solution based on the high-frequency signal injection to suppress the capacitor voltage fluctuations under the low-frequency operation suffers for the disadvantages as the high-frequency common mode voltage and the high circulating current loss. Therefore, this project plans to eliminate the high-frequency common mode voltage and reduce the circulating current loss by adopting the phase-coupled MMC topology, and the finite control set model predictive control (FCS-MPC) is adopted to meet the current tracking and structure concision requirements for the optimized system control. Corresponding research is around the crux scientific issues as the analysis of the system power integration, as well as the searching and action mechanism optimization for the FCS-MPC. Thus the research contents are conducted as follows: ①the compositions of the phase-coupled circuits are optimized and the high-efficiency power integration control thought based on the asymmetric arm mode is presented; ②a hierarchical structure for FCS-MPC is established and a low-complexity arm current MPC strategy is proposed, which is adopted to implement the high-efficiency low-frequency operation control; ③the influence mechanism of the sampling period on the stability of FCS-MPC is analyzed and the improving method for system steady-state performance under low sampling frequency condition is provided, which helps to ensure the current control precision for low-frequency operation. The research conclusion of this project will provide the theoretical foundation for solving the low-frequency operation problem of the MMC effectively, and promote the development of the high-power AC drive technology.

模块化多电平变换器(MMC)在大功率交流传动领域应用潜力较大，但解决其低频运行电容电压波动问题较为主流的高频信号注入方法存在输出高频共模电压、环流损耗高等缺点。本项目拟结合相间耦合型MMC拓扑消除高频共模电压并降低环流损耗，面向其系统优化控制对于电流跟踪性及结构简洁性的要求引入有限控制集模型预测控制(FCS-MPC)，围绕系统功率复合机理分析、FCS-MPC寻优及作用机制优化等关键科学问题展开研究，包括：①明确相间耦合型MMC相间电路的优化结构及配置，形成基于桥臂不对称运行的高效率功率复合控制思路；②建立分层FCS-MPC架构并提出低复杂度桥臂电流模型预测控制策略，实现高效率低频运行控制；③分析采样周期对FCS-MPC稳定性的影响机理并提出低采样频率条件下系统稳态特性的优化方法，保证低频运行电流控制精度。研究结论可为有效解决MMC低频运行问题提供理论基础，有望推动大功率交流传动技术的发展。

本项目以模块化多电平变换器（MMC）交流电机驱动的低频运行问题为主要研究背景，围绕变换器建模分析、模型预测控制优化等两方面内容开展研究。主要研究工作包括：1）分析了MMC拓扑子模块电容电压的波动机理，分析了具备相间功率传输通路的相间耦合型MMC，明确了可降低机侧高频共模电压的电路配置形式，构建了相间耦合型MMC变频驱动的低频运行调速控制环路，搭建了相间耦合型MMC变频驱动系统实验测试样机；2）结合相间耦合型MMC的控制特点及交流电机控制需求，优化了MMC模型预测控制建模及设计思路，提出了一种基于无差拍思想和分层架构的低复杂度桥臂电流模型预测控制策略，实现了相间耦合型MMC电机驱动系统的多目标有效控制，明确了相间耦合型MMC优缺点；3）研究了有限集模型预测控制稳定性分析及稳态特性优化方法，面向多种变换器系统提出了三种具备通用性的定频模型预测控制方法，提升了模型预测控制用于电力电子变换器的多目标控制精度。依托本项目研究，在国内外学术期刊上发表SCI论文7篇，EI核心论文1篇；申请项目相关国家发明专利8项，其中获得授权5项；培养硕士研究生7名，其中已毕业5名。

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