Unified Fault Tolerant Control of Bearingless Multi-three Phase Permanent Magnet Synchronous Machines

This paper proposes a fault tolerant control of a bearingless permanent magnet synchronous machine featuring a multi-three phase sectorial winding configuration able to manage both three phases open and short circuit faults. The challenge of calculating the reference currents to achieve a given torque and radial force production is tackled proposing a novel analytical formulation for both healthy and faulty operations. The proposed analytical framework provides a computationally efficient and physically interpretable method for current reference calculation in all operating conditions and allows drawing relevant considerations on the controllability and design of the machine when considering different number of three phase winding sectors. The proposed control strategy is experimentally validated using a prototyped bearingless triple three-phase permanent magnet synchronous drive. The tests carried out in a wide variety of healthy and faulty operating scenarios confirm the effectiveness of both bearingless and fault-tolerant operations achieved when implementing the proposed analytical method for the current reference calculation.