Switching-Table-Based Diagnosis-Free Fault-Tolerant DTC for Five-Phase PMSM With Any Phase Open-Circuit Fault

The conventional fault-tolerant direct torque control (DTC) strategy not only needs to diagnose open-circuit fault phase but also needs reconfiguration of switching table, transformation matrix, and structure of control system according to the specific fault phase, thus increasing the complication of the control algorithm. To solve this problem, a switching-table-based diagnosis-free fault-tolerant DTC for five-phase permanent magnet synchronous motor was proposed in this article. The novelty of the proposed strategy is the development of fault-tolerant switching table. Based on this, the conventional DTC without diagnosis can operate smoothly under both healthy and open-circuit fault conditions. The switching table does not need to change the sector division or the basic voltage vector (VV) and its dwell time that constitutes the virtual voltage vector (V
³
) when open-circuit fault occurs in any phase. Thus, the open-circuit fault diagnosis and the reconfiguration of control system can be avoided. The proposed DTC strategy can not only restrain the torque fluctuations caused by any-phase open-circuit fault but also reduce the third harmonic currents and have good dynamic performance both under healthy and fault conditions. The feasibility of the proposed strategy was verified by the experimental results.