Flux-Based Open-Switch Fault Diagnosis and Fault Tolerance for IM Drives With Predictive Torque/Flux Control

In this article, open-switch fault diagnosis and fault tolerance are proposed for induction machine (IM) drives with predictive torque control (PTC) or predictive flux control (PFC). Different from the conventional diagnosis methods for drives with finite control set model predictive control (FCS-MPC), which are based on the current, the proposed method is based on the flux error. As a result, this method can be extended to IM drive systems with PTC or PFC. It detects the fault by computing and accumulating the error between the predicted flux from the last sampling interval and the estimated flux at the current interval. Then, the polarity of the accumulated residual is utilized to localize the fault. For the fault-tolerant method, the three-phase four-switch (TPFS) inverter is chosen as it can keep working with only four switches. To reduce the torque ripple caused by the TPFS topology, a three-vector PFC method is proposed. Hardware-in-the-loop (HIL) tests are carried out to validate the effectiveness of the proposed methods. Compared to conventional diagnosis methods, the proposed one has a much faster diagnosis speed and the three-vector PFC outperforms the one- and two-vector methods.