An Experimental Investigation of Hybrid Cooling Solution for High Performance Traction Motor

This paper presents an experimental study on the thermal and efficiency impacts of the hybrid cooling system based on housing water jacket combined with the air- and oil-cooled rotor. The cooling system was designed for an 800 V traction motor used in e-mobility applications. The cooling system configuration and the experimental setup are described. The tests were carried out on a 380 kW prototype motor. The results indicate that the hybrid cooling system reduces both the stator and rotor temperatures compared to standard housing water jacket cooling. Impact of different rotor cooling solutions based on air, oil and a combination of them is studied in detail. In addition, the efficiency and drag losses of the prototype is evaluated under different thermal conditions of the rotor. The losses under different thermal conditions of the rotor are studied and it is shown that the rotor temperature will affect the efficiency on the motor, and different rotor temperatures are beneficial for different operational regions of the motor.