Fault-Tolerant MPC for Three-Level Inverters Fed Dual Three-Phase PMSM Drives with Harmonic and Common Mode Voltage Suppression

A single open-phase fault (SOPF) in a T-type three-level inverter-fed dual-three phase permanent magnet synchronous motor drive reduces the control degrees of freedom (CDF), causes harmonic-torque control conflicts and increases the current harmonic if the conventional full-order (sixth-order) space vector decoupling transformation (VSD) is retained. Moreover, SOPF introduces a fundamental-frequency sinusoidal bias into the common-mode voltage (CMV), heightening the risk of secondary faults. To address these issues, a fault-tolerant model predictive control with harmonic and CMV suppression is proposed. The strategy utilizes a reduced-order (fifth-order) VSD to reconstruct the post-fault motor model, ensuring CDF matching while decoupling harmonic and torque control. To address the post-fault challenges of uneven voltage vector distribution, low impedance in the harmonic plane, and CMV bias, the strategy employs a flexible dual-vector synthesis approach. This generates a set of virtual vectors with zero harmonic voltage and dynamically adjusts the vector sequence to suppress current harmonics. Furthermore, large-magnitude virtual vectors exhibiting low CMV are selected and subdivided into three groups based on their CMV characteristics: positive-bias, negative-bias, and zero-bias. These groups are then alternately applied according to the instantaneous CMV bias, enabling active CMV suppression across the full speed range. Additionally, a hybrid series-parallel weightless cost function topology is designed. This structure co-optimizes switching frequency and capacitor neutral-point voltage balance, thereby avoiding the weighting design challenges. Experimental results validate the effectiveness of the proposed strategy.