To enhance the operating performance of the common-bus open-winding permanent
magnet synchronous motor under single-phase open-circuit faults, this paper
proposes a model predictive torque control strategy with torque ripple
suppression. First, the operating principles of the model predictive torque
control system for both normal operation and single-phase fault conditions are
analyzed. Based on this analysis, the electromagnetic torque controller in the
model predictive torque control system is restructured. However, if the
conventional space vector modulation strategy used during fault-free operation
is continued, the required stator voltage cannot be achieved. Therefore, analyze
the phase relationship of the current before and after the fault, derive a new
Clark transformation matrix, and then based on the principle of torque
invariance that can be generated by the fundamental magnetic flux, derive the
coefficients of the Park transformation of the two-phase current. To simplify
the inductance matrix into a focusing matrix, a Park transformation matrix for
two-phase voltages can be derived. Based on this, derive a new coordinate
transformation matrix, and based on the new coordinate transformation matrix, a
torque formula considering the third harmonic magnetic flux is derived to
suppress torque ripple, and the model predictive torque control method is used
to control the motor system. Finally, the proposed fault-tolerant model
predictive control strategy is validated using MATLAB/Simulink. Simulation
results show that when a single-phase fault occurs in the motor drive system,
the proposed strategy can keep the electromagnetic torque and stator magnetic
flux ripple relatively small. The research results can provide theoretical basis
for the control of common busbar open winding permanent magnet synchronous
motors after phase failure.