Fault-tolerant converter for AC drives using vector-based hysteresis current control

This paper presents a fault-tolerant converter intended for AC regenerative drives requiring improved reliability and availability. The standard six-switch three-phase converter is rearranged in order to obtain a four-switch tree-phase converter (FSTPC) during post-fault operation. Thus, its performance relies heavily on the fault diagnostic technique to trigger the remedial procedures, and on the control strategy to guarantee proper post-fault operation of the drive. With the aim to achieve these two goals effectively without increasing significantly the control system complexity, it is proposed to integrate, into the drive controller, a new and simple voltage-based approach for open-circuit fault diagnosis (without additional sensors), and vector-based hysteresis current control of the FSTPC. The performance of proposed fault-tolerant converter is evaluated by means of experimental results with a permanent magnet synchronous machine (PMSM) drive.