A Fault-Tolerant Hybrid Control Strategy for Dual Three-Phase PMSM With Low Losses in Full Torque Operation Range

The high fault-tolerant ability of multiphase machines is an important advantage. Under open-phase faults (OPFs), to guarantee ripple-free torque, harmonic subspace current references should be adjusted. In this paper, a fault-tolerant hybrid control strategy is proposed for the dual three-phase permanent magnet synchronous motor (DT-PMSM), which is obtained by mixing minimum losses (ML) and maximum torque (MT) strategies in different proportions. The hybrid control strategy can effectively reduce the stator copper losses in the full torque operation range (TOR). Compared with the existing full-range minimum losses (FRML) control strategy, the hybrid control strategy can provide analytical solutions for current references of harmonic subspaces. Since there is no need for the offline global optimization process and prestored look-up tables, the implementation of the hybrid strategy is simple. Additionally, the difference between hybrid and FRML control strategies is also analyzed in this paper. Although the copper losses of the hybrid control strategy under optimal coefficients are similar to those of the FRML control strategy, the FRML control strategy cannot be regarded as a linear combination of ML and MT strategies. The proposed fault-tolerant hybrid control strategy can provide the unified analytical solutions for different types of multiphase motors and OPFs. Simulation analysis and experimental results demonstrate the effectiveness and feasibility of the proposed strategy.