Open-Circuit Fault Tolerant Study of Bearingless Multi-Sector Permanent Magnet Machines

This paper presents a fault tolerant study of a multiphase sectored permanent magnet synchronous machine involving a tripel three-phase winding. The machine electro-megnetic model is written in a general way so that it can be extended and applied to all machines with a similar winding structure. An expression of the d-q axis reference currents of each three-phase winding as a function of the x - y force components and torque is provided taking into acccunt the Joule losses minimization. Then, the case of open-circuit of one winding sector is considered, the model of the faulty machine derived and an expression of the new reference currents needed to generate radial suspension force and motoring torque is written.Finally, the theoretical analysis are validated through finite elements simulations and the levitation performance of the machine considered are evaluated in the Matlab-Simulink environment in the case of one sector fault per time.