Abstract
The motor design methodology applied here is to first define the rotor outside diameter (OD) based on strength of materials and then to proceed both inward (i.e., define rotor slot geometry, back iron thickness, and shaft diameter, etc.) and then outward (i.e., define stator slot geometry, back iron or stator yoke thickness, and how it interfaces to the housing and thermal management system). Upon completion of those actions, the final step will be to stack out (e.g, add laminations) the motor as needed to meet the torque requirement. Therefore, the most important parameter at the initial sizing stage is to define the rotor surface tangential velocity, Vt, that a copper rotor can tolerate and retain its robustness. In this design Vt is taken as 105 m/s to be somewhat conservative, recognizing that large synchronous motors and generators for example have Vt of approximately 180 m/s. A final note, the stator design detailed in this and subsequent sections will be somewhat larger in diameter than needed to meet the specifications, but no attempt will be made to optimize the stator slot design at this point – that will require finite element analysis, the subject of a follow-on technical report.