A study of the effects of the magnetization tolerance in the manufacturing process on permanent magnet synchronous machines

Nowadays Fractional Slot Permanent Magnet Synchronous Machines are getting more and more relevance due to their cost effectiveness and low torque ripple. Therefore, they are suitable for high comfort applications. However, if during the manufacturing process assembling errors are made or the manufacturing tolerances are not properly set, the ideal conceptual high comfort characteristics could not be achieved. Hence, in this paper an error in the magnetization process caused by an incorrect alignment of the magnetizer is studied. Demagnetized magnets are placed in the rotor and then a magnetizer magnetizes them. Due to an excessive tolerance alignment of the magnetizer, not all the magnets are equally magnetized neither each magnet is homogeneously magnetized. In the paper the failure pattern is analyzed, and the performance of the machine is studied by Finite Element Analysis and experimentally. The results show a significant reduction of the comfort and a higher current consumption.