Active Fault-Tolerant Control Strategy of ANPC Three-Level Inverter Based on Sliding Mode Control

In order to solve the fault-tolerant problem of open-circuit fault of power switching devices in each arm in active neutral point clamped (ANPC) three-level inverter, an active fault-tolerant control (FTC) strategy based on sliding mode (SM) control is proposed. First, on the basis of establishing the state-space model of the inverter system, the fault characteristic signal is extracted and introduced. Then, the fault-tolerant controller using SM is designed to adjust the output voltage control signal in real time by reconstructing the SM control law after the fault. Based on the above strategy, the SVPWM control algorithm is adjusted to reconstruct the voltage space vector, which further changes the vector sending sequence. Consequently, the stable operation of inverter after FTC is realized and verified by simulation. Results show that the closed-loop FTC method with SM controller has better dynamic and steady-state response characteristic than open-loop control method, which meets the requirements of higher control accuracy. The proposed active FTC strategy achieved the expected goals in terms of effectiveness and feasibility.