NPC / H五电平逆变器低开关频率有限控制集模型预测控制研究

Aiming at common problems such as weighting factor setting design difficulty, large amount of prediction computation and high performance control under low switching frequency in NPC/ H five-level inverter low switching frequency control based on finite control set model predictive control (FCS-MPC), the main research contents are as follows: Based on the theory of hierarchical optimization and the idea of satisfactory optimization, a unified model with low computational load and no weight factor will be established to systematic solve the problem of weighting factors and achieve the minimum common-mode voltage output control. The strategy will provide the foundation for the analysis and design of FCS-MPC system with different topology multi-level converters; On this basis, to achieve the minimum switching loss control over multiple cycles in the future, a new general low switching frequency control strategy without increasing the system operation is proposed, which is based on the principle of time-domain expansion; Aiming at the problems of the traditional single-vector FCS-MPC algorithm, such as variable switching frequency and large current ripple, a two-stage FCS-MPC-SVPWM strategy will be researched and established, which helps to improve system control performance and simplifies SVPWM aspects of multilevel inverters; The formation of a completely independent intellectual property rights of low switching frequency finite control set model predictive control core algorithm, hope to make a certain contribution to the research system of low-switching frequency control theory for rich multi-level converters.

针对NPC/H五电平逆变器低开关频率有限控制集模型预测控制（FCS-MPC）面临的计算量大、权重因子整定困难及低开关频率下高性能控制等共性问题，主要研究内容为：拟采用分层优化理论并结合满意优化思想，展开低运算量、无权重因子FCS-MPC系统统一建模研究，系统解决权重因子整定问题，实现最小共模电压输出控制，为不同拓扑多电平变换器FCS-MPC系统的分析、设计奠定基础；在此基础上，为实现未来多个周期内的最低开关损耗控制，拟基于预测时域扩展原理，探索一种不增加系统运算量的新型通用低开关频率控制策略；针对传统单矢量FCS-MPC开关频率不固定，稳态电流纹波大等问题，研究并建立一种二段式FCS-MPC-SVPWM策略，提高系统控制性能，并简化多电平逆变器SVPWM环节。形成具有完全自主知识产权的低开关频率有限控制集模型预测控制核心算法，为丰富并完善多电平变换器低开关频率控制理论研究体系做出一定贡献。

针对NPC/H五电平逆变器低开关频率有限控制集模型预测控制（FCS-MPC）面临的计算量大、权重因子整定困难及低开关频率下高性能控制等共性问题展开研究。提出了一种基于分层满意优化的低运算量、无权重因子有限集模型预测电压控制(FCS-MPVC)策略，为FCS-MPC技术在多电平变换器中的推广应用提供了一种新的设计思路。通过对控制目标的分层满意优化设计，避免了权重因子整定环节，并实现了最小共模电压输出控制；将对电压矢量的多次电流预测转变为对参考电压的单次电压预测，解决了预测运算量过大问题。仿真与实验结果表明该FCS-MPVC策略具有良好的控制性能，预测运算量降低为1次，输出共模电压基本控制在直流侧电压的1/6倍。提出了一种基于预测时域扩展的新型通用低开关频率控制策略，有效降低了相邻控制周期间的开关切换次数，实现了全调制度范围内的低开关频率控制。开关频率可控制在125-400Hz之间，当电流调制度为0.81左右时，开关频率最高降幅可达48%。该策略无相关权重因子整定问题，不增加系统预测运算量，且不受变换器拓扑结构及预测模型的限制，为大功率多电平变换器的低开关频率控制提供了一种通用的新方法。提出了一种低开关频率下的二段式FCS-MPC-SVPWM策略，并系统解决了矢量选择、矢量时间和矢量次序等问题，提高了系统静态性能，降低了采样频率。仿真分析表明，采用该策略后转矩脉动幅值相对于单矢量减小近50%。提出了一种NPC/H五电平逆变器双桥臂容错运行控制方法。在单桥臂故障时，可使调速系统稳定工作于三电平区域，且调速系统动态性能不受影响，满足调速系统全载半速运行要求，为NPC/H五电平变换器驱动的变频调速系统提供了一种新的容错运行方法，提高了调速系统的运行可靠性。