针对T形逆变器发生开路故障后容易导致输出谐波增大、抗干扰能力差的问题，提出一种基于电压残差的T形三电平逆变器开路故障诊断方法。首先分析T形逆变器的工作原理和开路故障特性，通过空间矢量脉宽调制技术，建立系统的状态空间模型。其次，利用正常工况下线电压的参考值与实际传感器测量所得到的电压值进行比较，结合低通滤波处理获得电压残差信号，将其与故障检测阈值对比判断系统是否发生故障。然后建立诊断变量与故障开关管之间的逻辑关系，实现逆变器单管故障的精确定位。最后，通过MATLAB平台对所提出的故障诊断方法进行验证，仿真结果表明，该方法的故障诊断速度快、易于实现且可靠性高。

In order to solve the issue of increasing output harmonics and poor anti-interference ability after open-circuit fault of T-type inverter, an open-circuit fault diagnosis method of T-type three-level inverter based on voltage residual was proposed. Firstly, the working principle and open-circuit fault characteristics of T-type inverters were analyzed, and the state-space model of the system had been constructed via the space vector pulse width modulation strategy. Secondly, the line voltage detected by the actual sensor was contrasted with the reference value of the down-line voltage under normal conditions. The voltage residual signal was obtained through low-pass filtering processing. Compare the residual error with the fault detection threshold to determine whether the system was faulty. Then the logical relationship between the diagnostic variable and the fault switch tube was established to achieve the precise location of the inverter single tube fault. Finally, the proposed fault diagnosis method was verified by the MATLAB platform, and the simulation results show that the method is easy to implement, fast and reliable.