Abstract: In order to improve the operation reliability of the three⁃level PV inverter, an open⁃circuit fault detection and a voltage space vector redundancy fault⁃tolerant control method based on the improved current flow path were proposed. First, based on the three⁃phase three⁃level PV topology structure, the circuit current flow path after the open⁃circuit fault of each partial power device was analyzed in detail, the fault detection could be carried out by the current size flowing through the clamping diode and the load, the switching state of the switching device, and the fault type could be classified by injecting the under⁃excitation reactive current in a short time. Then, the change of the voltage space vector of the inverter after the open⁃circuit fault of the power device in different positions was theoretically explored. And the fault⁃tolerant control was completed according to the distribution law of the voltage space vector after the inverter fault and the redundancy vector of the inverter. The proposed method was fast in fault detection and fault⁃tolerant control without additional hardware cost and complex calculation. Finally, a prototype with rated power of 10 kW was built to verify the effectiveness and reliability of the proposed method.

Key words: Fault detection, Fault?tolerant control, PV inverter, Three?level, Open?circuit fault, Voltage space vector

摘要： 为提高三电平光伏逆变器运行的可靠性，提出基于改进型电流流通路径开路故障检测和电压空间矢量冗余容错控制方法。首先，以三相三电平光伏逆变器拓扑结构为基础，详细地分析了各部分功率器件发生开路故障后电路电流流通路径，利用流过钳位二极管和负载的电流以及开关器件的切换状态进行故障检测，通过短时间内注入欠励磁无功电流对故障类型进行分类。然后，从理论上探索不同位置的功率器件发生开路故障后逆变器电压空间矢量的变化情况。根据逆变器故障后电压空间矢量的分布规律和逆变器自身的冗余矢量完成容错控制。提出的方法无需额外的硬件成本和复杂的计算，故障检测和容错控制速度快。最后，搭建一台额定功率为10 kW的样机验证提出方法的有效性和可靠性。

关键词: 故障检测, 　容错控制, 　光伏逆变器, 　三电平, 　开路故障, 　电压空间矢量