Irreversible Demagnetization of a Large Capacity Line-Start Permanent Magnet Synchronous Motors considering Influence of Permanent Magnet Temperature

Abstract

This paper investigates the irreversible demagnetization (ID) of a large capacity line-start permanent magnet synchronous motor (LSPMSM) considering influence of permanent magnets’ (PMs) temperature. The phenomenon of ID occurs on the pull-in stage and close to the cusp of magnet on the direct-axis direction. The PMs’ temperature causes the demagnetization curve to move down and the knee point to shift up. The extensive area ID of magnet will lead to pulling in synchronism failure and operation at the asynchronous state. A prototype is fabricated to validate the analysis that temperature of PMs will bring more serious ID risk and degradation of motor performance.