Fault-Tolerant and Current Compensation Control Based on Set-Membership Estimation for Three-Phase Four-Bridge PMSM Drive System

For the issue of the inverter open-circuit faults of the permanent magnet synchronous motor (PMSM) drive system, this paper presents a fault diagnosis and fault-tolerant control method based on set-membership estimation. Firstly, the mathematical model of the motor drive system is established using the discrete switch signals and the continuous current state variables. Then, an ellipsoid set estimation method is designed for fast fault monitoring and location for subsequent fault-tolerant control. Then, this paper divides the fault-tolerant control design into two types based on the specific faulty tubes and the directions of the fault phase currents. One approach is to switch when the current drops sharply upon a fault directly and use the residual difference between the estimated and actual current values as current compensation. Another approach is to wait for the current in the faulty phase to approach zero before switching to the backup phase when the fault has little impact on the current. The simulation results show that the waiting-to-switch method has little effect on current and speed, which is no different from the normal operation of the motor. A direct switch at this point will cause the current to drop sharply to zero, with a speed fluctuation of 11 ms. In the case of a sudden drop in current, the method with current compensation is 3 ms faster than that without current compensation, and the efficiency is increased by approximately 22.2%. Both fault-tolerant control designs can effectively improve system performance and stability.