Demagnetization analysis of line-start permanent magnet synchronous motor with composite rotor under abnormal conditions

Line-start permanent magnet synchronous motor with composite rotor is a new type of permanent magnet synchronous motor, which uses eddy currents induced in solid rotor and copper bars to achieve self- starting capability. In order to research the demagnetization of permanent magnets under three-phase short circuit and out-of-step fault, the finite element model considering saturation, eddy currents and other factors are established. The effects of moment of mutation, initial load torque and initial moment of inertia are studied. The rules of demagnetization point of permanent magnet in two kinds of faults are summarized.