A Model Predictive Control Method for Two Induction Motor Drives Supplied by Four-leg Inverter

The four-leg inverter is potential for non-redundant fault-tolerant control to solve multi-leg faults in two-motor drives. This paper proposes a non-redundant fault-tolerant control scheme based on the four-leg inverter. When there are open-circuit faults in both inverters, the fault phases of both motors are connected to the neutral point of DC-link capacitors. Obviously, this will cause more severe capacitor voltages offset and fluctuation than only one motor phase is connected to the neutral point. This paper proposes a fault-tolerant control algorithm based on predictive torque control method to solve this shortcoming. The balanced three-phase current and stable output torque and stator flux are guaranteed. The capacitor voltages offset is suppressed, improving the DC-link voltage utilization. Besides, the algorithm independently calculates the cost function for each motor, eliminating the coupling problem in voltage suppression. It reduces the calculation time and can be applied to multi-motor systems. The effectiveness of the algorithm is verified by experiment results.