Calculation and Analysis of Motor Dynamic Stress Considering Multiphysical Field Loads for In-Wheel Electric Vehicle Applications

The in-wheel motor (IWM) bears the combined action of thermal load and various mechanical loads such as vibration load from road excitation, electromagnetic torque, electromagnetic force, gravity, and centrifugal force of rotating components during vehicle operation. This will accelerate the fatigue of the IWM and affect the use and safety of the vehicle. Many efforts have been devoted to this area. However, the comprehensiveness of the loads, coupling properties between multiphysical field loads, and the time variability of vehicle operating conditions are still the main challenges for the calculation and analysis of the IWM dynamic stress. To investigate the motor dynamic stress for in-wheel electric vehicle applications under such difficulties, a 15 kW IWM is taken as the research object in this article. On the basis of analyzing the coupling relations of various loads for the motor, the global coupling model for dynamic stress analysis of the motor under the combined action of thermal and mechanical loads is established. Moreover, the effectiveness of the established model is verified by experiments. Then, the established model is used to calculate and analyze the thermal-mechanical coupling stress of the motor under different vehicle working conditions. Furthermore, the influence law of vehicle working condition on the dynamic stress of the motor is obtained, and the main inducing factors of the dynamic stress of each component are identified. This article lays a foundation for the fatigue damage analysis and life prediction of IWMs.