Fault-Tolerant Reconfiguration for Two Cascaded Two-Level Inverters Feeding the Dual Open-End Stator Windings of an Induction Motor

The primary goal of this work is to significantly enhance the availability and operational reliability of a variable speed drive system, a factor critical for industrial processes where downtime must be minimised. This improvement is rooted in a robust power architecture: a dual open-end stator winding induction machine is utilised, where each entry of the machine is supplied by two cascaded two-level inverters, thereby increasing the system’s inherent redundancy. The control strategy employed is the phase disposition pulse width modulation (PD-PWM) technique. The study comprehensively analyses the system’s behaviour under various fault configurations, focusing specifically on the failure of a single cascaded inverter and rigorously defines the critical operating and control conditions that must be implemented to maintain system functionality. Simulation results successfully demonstrate the effectiveness of this machine-cascaded inverter association in a degraded operating mode, ensuring continuity of service with rotation speeds very close to the nominal value, thereby validating the robustness of the chosen architecture for high-reliability applications.