Demagnetization characteristics of permanent magnet synchronous machines

This paper presents the calculated demagnetization characteristics of different types of permanent magnet synchronous machines (PMSMs) under the influence of demagnetizing MMF contributed by the stator currents (i.e., armature reaction). The demagnetization of NdFeB magnets is quantified in terms of demagnetized magnet volume and loss of magnet remanence using finite element (FE) analysis. The impact of cross-coupled q-axis current and the rotor position are also investigated. The results comparing seven PM machine configurations show that burying the magnets inside the rotor using interior PM (IPM) rotor configurations generally improves the demagnetization performance. In addition, the machine configurations with distributed windings generally provides better demagnetization-withstand capabilities than the configurations with fractional-slot concentrated windings.