Development of a 7.5kW High Speed Interior Permanent Magnet Synchronous Spindle Motor for CNC Milling Machine

In this paper, two different type interior permanent magnet (IPM) motor designs are proposed for Computer Numerical Control (CNC) milling machine application as spindle motors. An existing surface mounted permanent magnet motor is used as a reference motor. Both spoke type and v-type Interior Permanent Magnet (IPM) motor alternatives are designed and optimized in detail. The results of the two IPM motors are compared with the reference Surface Permanent Magnet (SPM) motor for the same design requirements. Detailed loss analysis are also performed for the desired motor structure at high speeds. A prototype motor is manufactured and initial experimental tests are performed. Detailed comparison between Finite Element Analysis and test data are also presented. It is shown that it is possible to have an optimized IPM motor for such high speed spindle application.