并网变换器电流重构模型预测容错控制

当传统并网变换器发生桥臂故障时,通过连接故障相到直流侧电容中点,重构为三相四开关容错运行结构。针对三相四开关容错变换器的交流电流传感器故障问题,提出了一种基于电流重构的模型预测功率控制方法。首先,利用采样的直流电流和正常交流传感器信息,并根据变换器电压矢量与电流关系重新构造出三相电流。其次,建立容错变换器功率预测模型,利用重构电流参与容错变换器的模型预测控制,应用使代价函数取得最小值的开关矢量。最后,搭建仿真和实验平台进行验证,结果表明所提控制策略有效,输出功率稳定,实现了并网变换器在桥臂和传感器双重故障下的容错运行,提高了系统的可靠性。

Model Predictive Fault-tolerant Control of Grid-connected Converters with Current Reconstruction

When the bridge arm fault occurs in a traditional grid-connected converter, by connecting the fault phase to the DC-side capacitor midpoint, the converter is reconstructed as a three-phase four-switch (TPFS) fault-tolerant operation structure. A model predictive power control method based on current reconstruction is proposed to solve the problem of AC current sensor fault in the TPFS fault-tolerant converter. First, using the sampled DC current and normal AC sensor information, the three-phase current is reconstructed according to the relationship between the voltage vector and current. Second, the power prediction model of the fault-tolerant converter is established, the reconstructed current is used to participate in the model predictive control of the fault-tolerant converter, and the switching vector that minimizes the cost function is applied. Finally, simulation and experimental platforms were built for verification. Results show that the proposed control strategy is effective, the output power is stable, and the fault-tolerant operation of the grid-connected converter under the dual faults of the bridge arm and the sensor is realized, which improves the system reliability.