Development of Direct Oil Cooling Solutions for E-mobility Traction Motors : Part II: Rotor Cooling Concept

This paper presents different oil cooling configurations with possibility to be used in electrical machines designed and developed for e-mobility application. Following the verification of the simulation results on the stator cooling by measurements on a prototype carried out in Part I, the focus in this paper part is placed on the rotor cooling. Different cooling solutions based on hollow shaft, rotor lamination channels and wound rotor are presented and discussed. The proposed configurations are evaluated using both transient and steady-state fluid flow simulations and a comparison in results is presented.