【目的】针对有限控制集模型预测控制(FCS-MPC)应用于中点钳位(NPC)逆变器时存在的开关频率不固定的问题，本文提出了一种固定开关频率三矢量最优序列模型预测控制(FSF-TOS-MPC)策略。【方法】首先，采用空间扇区划分来简化寻优算法，缩小参与模型预测寻优的基本电压矢量范围，从而减小运算量；然后，通过对直流侧中点电位和负载侧三相电流的极性判别，进行三矢量最优开关序列分区预选，同时引入Karush-Kuhn-Tucker条件求解开关序列中各电压矢量的作用时间，确保各矢量作用时间恒大于零，固定开关频率。最后，通过构建代价函数进行多目标控制，实现参考电流跟踪和直流侧中点电位平衡。【结果】通过仿真对传统FCS-MPC、优化FCS-MPC和本文所提FSF-TOS-MPC策略进行不同工况下的对比。仿真结果表明，FSF-TOS-MPC策略能够确保逆变器在固定开关频率下稳定运行，从而有效抑制输出电流总谐波畸变率，提升系统动态响应特性，实现中点电位平衡。进一步搭建试验平台对所提策略进行验证。试验结果与仿真结果基本一致，验证了所提策略的有效性。【结论】本文所提FSF-TOS-MPC策略的控制性能优越，为NPC逆变器模型预测控制中存在的开关频率不固定问题提供了一种有效的解决方案。

[Objective] Aiming at the problem of unfixed switching frequency when finite control set model predictive control (FCS-MPC) is applied to neutral-point-clamped (NPC) inverters, this paper proposes a fixed switching frequency three-vector optimal sequence model predictive control (FSF-TOS-MPC) strategy. [Methods] Firstly, spatial sector division was used to simplify the optimization algorithm, narrowing the range of basic voltage vector involved in model predictive optimization, thus reducing the amount of computation. Then, through the polarity discrimination of the neutral-point potential of the DC side and the three-phase currents of the load side, the three-vector optimal switching sequence partition pre-selection was carried out. And the Karush-Kuhn-Tucker condition was introduced to solve the duration of each voltage vector in the switching sequence, to ensure that the duration of each vector was constant greater than zero, and the switching frequency was fixed. Finally, multi-objective control was carried out by constructing a cost function to achieve reference current tracking and DC side neutral-point potential balancing. [Results] The conventional FCS-MPC, optimized FCS-MPC and the FSF-TOS-MPC proposed in this paper were compared under different operating conditions by simulation. Simulation results showed that the FSF-TOS-MPC strategy can ensure the stable operation of the inverter with fixed switching frequency, thus effectively suppressing the total harmonic distortion of the output current, improving the dynamic response characteristics of the system, and achieving the neutral-point potential balance. [Conclusion] The FSF-TOS-MPC strategy proposed in this paper has superior control performance, and provides an effective solution to the problem of unfixed switching frequency in the model predictive control of NPC inverters.

黑龙江省优秀青年教师基础研究支持计划(YQJH2023254)