Demagnetization Analysis of a Line Start PM-Assisted Synchronous Reluctance Motor

Taking a 3kW 380V line start permanent magnet-assisted synchronous reluctance motor (LS PMaSynRM) as the research object, a time-stepping finite element model considering the overall and local irreversible demagnetization is established in the paper. By calculating the influence of the design parameters of squirrel cage on the demagnetization, the selection method of amount of cast aluminum and parameters of end ring are determined. And the influence of starting voltage and sudden load on the demagnetization is analyzed. The results show that there is a starting voltage corresponding to the minimum risk of demagnetization of PMs for LS PMaSynRMs. If a starting voltage lower or higher than it, the risk of demagnetization will be increased. After the sudden load applied, the risk of demagnetization is the greatest when the motor is running out of step and the speed fluctuates below the synchronous speed.