Influence of rotor’s cage resistance on demagnetization process in the line start permanent magnet synchronous motor

This paper deals with the finite element analysis of the demagnetization process of the line start permanent magnet synchronous motor. Special attention has been paid to demagnetization risk assessment after resynchronization during a short-term supply power outage. The current and torque waveforms have been determined assuming the difference depending initial rotor position angle. It has been demonstrated that the highest demagnetization risk occurs when resynchronization (motor reclosing) is performed when induced electromotive forces are in anti-phase to the supply voltage waveforms. The effect of cage winding resistance on the risk of demagnetization is examined and discussed.