Six-Phase Fault-Tolerant Inverter using a Multilevel Nine-Switch Converter

This work presents a fault-tolerant topology based on a multilevel nine-switch converter. The proposed converter can supply either a six-phase motor or two three-phase induction motors, suitable for Electric Vehicles or for similar commercial or industrial applications. A Space Vector Modulation current control mode associated to a fault logic decision algorithm is adopted to control the proposed topology in normal and faulty operation. With the suggested configuration and the corresponding multilevel current controller, it is feasible to achieve two sets of three-phase balanced AC currents, while also minimizing harmonic distortion, even when withstanding most open-circuit malfunctions in power semiconductors. Besides, by making changes to the control strategy, it becomes feasible to recover some of the available output power and mitigate the effect on the torque and speed of the motor(s) during faulty conditions. Both the theoretical operation of the suggested topology and control approach and multiple simulation results showcase the effectiveness of the proposed configuration and the control strategy implemented.