Multireference Frame Based Open-Phase Fault Modeling and Control for Asymmetrical Six-Phase Interior Permanent Magnet Motors

Multireference frame based asymmetric six-phase interior permanent magnet motor modeling and control strategy under single open-phase fault are investigated in this article. The motor modeling under healthy operation is firstly established based on a dual dq-axis synchronous rotating frame. With this dual dq-axis frame, the motor modeling considering the magnetic saturation effect under open-phase fault has been derived. By introducing a dual-direction rotating frame, the stator current under single open-phase fault can be treated as the sum of a positive current sequence and a negative current sequence. With this dual-direction rotating frame, the two current sequences can be transformed into two dc components for fault-tolerant operation. Fault-tolerant control schemes with maximum torque per ampere for copper loss minimization and torque maximization are developed, respectively. Finally, the validity of the proposed modeling and control are evaluated by experiments under both steady and transient scenarios.