CAE-based Electro-Thermal Characterization and Design Optimization of Automotive Inverter Busbars

High power density demands in automotive inverters need precise thermal management to ensure efficiency, reliability and extended component lifetime. This paper presents a systematic, integrated electro-thermal workflow utilizing Computer-Aided Engineering (CAE) tools to characterize and optimize internal inverter components by directly linking electrical performance to thermal behavior. The methodology comprises three main steps: first, detailed frequency-dependent electrical parameters (RLCG, Z, S) and current density maps are extracted using computational calculations by ANSYS HFSS and ANSYS Q3D Extractor. Second, these parameters inform comprehensive power loss calculations (conduction, dielectric, switching), which are then mapped onto detailed 3D thermal fields using Computational Fluid Dynamics (CFD) through ANSYS Icepak. Finally, the results are analyzed to identify critical components and inform targeted design modifications. The workflow's effectiveness is demonstrated through a case study on generic DC busbars. Key findings include the identification of hot spots due to current convergence, thermal analysis between positive and negative busbars, and the successful application of optimization strategies. Increasing copper busbar thickness from 1.8mm to 2.5mm reduced maximum temperature by 23.8% (from 72.0°C to 58.15°C) and total power losses from 14.44W to 10.58W. A cost-benefit analysis showed that replacing 1.8mm copper with 2.5mm aluminum preserves the electrical behavior and the temperature distribution behavior and offering significant material cost, saving up to 54.77% for the positive busbar and 56.2% for the negative busbar compared to its original cost. This integrated approach provides detailed component-level insights crucial for iterative design improvement in high-performance power electronics.