Comparison of Demagnetization Behavior of Radial and Halbach Array PMs in Fault-Tolerant Synchronous Machines Operating with Open Phases

This paper presents a comparative study of the demagnetization behavior of permanent magnets arranged in the radial and Halbach array directions during the operation of fault-tolerant permanent magnet synchronous machines with open phases. Finite element analysis has shown that Halbach array permanent magnet synchronous machines with open slots offer the highest power density, have higher losses in permanent magnets and provide worse demagnetization picture at high temperatures in permanent magnets. In contrast, the machines with radially arranged permanent magnets and semi-closed slots generate higher losses in the stator winding, lower losses in permanent magnets, and provide a better demagnetization picture at high temperatures in permanent magnets, in comparison to the Halbach array machine. Finally, radially arranged permanent magnets have better demagnetization picture during short-time overcurrent in the stator winding, supplied by the converter.