Dynamic Modeling of Motor Deep Groove Ball Bearing Skidding and Simulation Study of Temperature Field Characteristics

High-speed traction motors in electric vehicles (EVs) subject their support bearings to severe mechanical and thermal loads. Bearing skidding and frictional heat generation can cause abnormal temperature rises, whereas uncertainty in convective heat transfer coefficients limits the accuracy of thermal simulations. This study investigates the skidding dynamics and temperature field of a motor deep-groove ball bearing (DGBB). A 35-degree-of-freedom dynamic model is established using the lumped-mass method to analyze rolling-element contact, skidding, and cage collisions at different speeds. A heat-generation and heat-transfer model is then developed based on bearing friction theory and moving-heat-source theory. The convective heat transfer coefficients are calibrated against measured temperatures using the non-dominated sorting genetic algorithm II (NSGA-II) within an integrated MATLAB–ANSYS framework, after which the temperature fields under constant- and variable-speed conditions are simulated. The results show that the rolling-element–raceway contact forces vary periodically, collisions between the rolling elements and cage are intermittent, and increasing speed intensifies the contact-force fluctuation and the ball–cage impacts and raises the skidding velocity, although the skidding ratio decreases. The component temperatures decrease in the order inner ring, rolling elements, outer ring and cage, and respond dynamically to changes in speed and load. The time-averaged cage speed agrees with the theoretical value to within 1% over 1000–10,000 rpm, and the calibrated thermal model reproduces the measured ring temperatures to within about 2 °C. The findings provide a useful reference for temperature prediction and thermal management of EV motor bearings.