A Direct Rotor Oil Cooling Concept for an Electrically Excited Synchronous Propulsion Motor

This paper introduces a direct oil cooling concept for rotor coils of an electrically excited synchronous propulsion motor. The proposed approach utilizes a hollow shaft and two distinct laminations to guide non-conductive, ultra-low-viscosity automotive oil onto the rotor coils. Radial channels are positioned at the rotor center to transfer oil from the hollow shaft to the axial channels at the outer surface of the rotor. Axial channels direct the coolant from the radial channels and splash it onto the rotor end windings. The proposed approach enhances the thermal management of the heat generated by rotor coils, and helps improve the motor performance and power density. Computational fluid dynamics (CFD) simulations were conducted to analyze the effectiveness of the cooling method under various operating conditions.