Modeling and control of a fault-tolerant multiphase induction motor drive

The conventional standard three-phase induction motors cannot operate inherently after the loss of a phase. The two-phase operation of a three-phase induction motor cannot supply the necessary performance in terms of torque and output power in applications that require high reliability such as electric traction applications, and electric ship propulsion. Therefore, one of the means to overcome this drawback is the addition of more phases to the motor, which forms the main focus of this thesis. This research aims to develop the control system of a six-phase induction motor with a single neutral point, which can function in both the six-phase (healthy) and five-phase (faulty) modes. The characteristics of this motor serve the purpose of reliable operation in case of a loss of a phase or more phases. Three subspaces were introduced to separately map fundamental, third, and fifth harmonics of the air-gap magnetic field. The Indirect Field-Oriented Control (IFOC) was considered to control the motor through PI controllers under normal operation and resonant PI controllers under faulty operation. The analysis of the configuration has been done through the Full Order Transformation (FOT) method. In conclusion, it was shown that the developed drive appears promising in so far as it maintains performance quality under faulty conditions, far better than the conventional three-phase design.