Design Process of a 4 kW Class Interior Permanent Magnet Synchronous Motor for Semiconductor Vacuum Pump Applications

This paper presents a design process for a 4 kW class interior permanent magnet synchronous motor (IPMSM) for semiconductor vacuum pumps. Based on a conventional induction motor, inverter voltage, current density, and slot fill factor limits are established. Four pole-slot combinations (6/9, 8/12, 10/15, and 12/18) are evaluated at a fixed pole-to-slot ratio of 2:3. For each combination, the electric-to-magnetic loading ratio is adjusted to minimize current density. The stator outer diameter and stack length are then systematically adjusted within the design constraints to determine minimum-volume candidates. Considering electromagnetic performance and inverter limitations, the 8-pole/12-slot design is selected and refined through rotor and stator geometry optimization to reduce cogging torque and torque ripple. Finite element analysis shows a shaft output of 4.46 kW and an efficiency of 96.42 %, with a 60.1 % reduction in stator-envelope volume relative to the reference induction motor.