How to measure the demagnetization of permanent magnet synchronous machines used in explosive environments

The performance of permanent magnet machines is directly dependent on the magnetic properties of permanent magnets. In this paper, firstly the measurement of the magnetic loss and the demagnetization effect on the permanent magnet (PM) of a surface-mounted permanent magnet synchronous machine are presented. The magnetic loss is measured in the PM in a closed magnetic circuit and compared with a finite element simulation. Secondly, this paper presents a variation of the magnetic properties of permanent magnets which takes temperature dependency effects into account in open and closed magnetic circuits.