Commercial Vehicles Busbar Cooling Concepts

Abstract

With the paradigm shift in transport, the emergence of sustainable technology has gained emphasis over the past few years. In an effort to create an emission-free world, BEVs are focused, and electric trucks are no exception. The heavy need for power in trucks leads to the overall heating of the busbars and, eventually, a gradual loss in current carrying capacity. The integration of a cooling concept along with busbars adds to the power junction box’s weight, cost, and performance and serves as the project’s background. There is a need to effectively cool down busbars and increase their operating temperature while considering weight and cost parameters. The project follows a systematic product development approach from requirement specification to concept selection and prototyping of the selected concept. The process was applied to redesign and optimize the existing cooling concept for busbars at Volvo Trucks in terms of material selection, concept design, and performance, accompanied by the simulation to validate the results. Various concepts for cooling were explored and mapped out in the idea-generation table, with the decision to pursue further development of direct liquid cooling accompanied by different crosssections and material selection for the busbars. These comprehensive results are further justified through thermal and fluent simulations to evaluate the maximum temperature, thermal conductivity, and safety. The final concept consists of a C-shaped busbar attached to an aluminum coolant tube underneath it. The hollow geometry profile of the aluminum tube enables direct cooling while being insulated with an electrical insulation layer to prevent contact between the coolant and the current-carrying copper busbar. The final concept achieved a reduction of 18.8% in the maximum temperature of the busbar. The final design also attained a weight of 45.4% compared to the existing design due to the employment of aluminum material. The material cost is reduced as the solid copper busbar is replaced with copper and a cheaper material option of aluminum, constituting the same electrical density while minimizing the weight. Hence, the thesis has validated employing a direct cooling method with proper material combinations and safety considerations to improve the cooling efficiency in a busbar.