Ampacity of power bus bars for Hybrid-Electric or Electric Vehicles

The transient and steady-state thermal modelling of a power bus bar used in automobile power electrical architectures is presented in this paper. Using the developed model, the current carrying capacity, also called ampacity, of this kind of power cable can be accurately predicted. After brief information about bus bars for hybrid-electric vehicle (HEV) and electric vehicle (EV), the study then focuses on the DC bus bar modelling. This mathematical model includes 3 principal steps: a carried out subdivision of the geometry based on the mesh network method. Then, a study of the heat transfers is pointed out, particularly about the external surfaces (convection and radiation). The Crank-Nicolsonpsilas implicit method then permits to numerically solve the obtained matrix system in order to predict the bus bar temperature supplied by an important current. The mathematical model has been validated by several experiments on samples located in a climatic chamber. Finally, the model can be extended to a low frequency AC bus bar considerating the skin effect in conductor material and the dielectric losses in insulation material.