Inverter housing design for BEV

Sammanfattning

This bachelor’s thesis presents the design and structural optimisation of an inverter housing for a heavy-duty electric vehicle application. The objective of the project was to reduce overall mass, improve manufacturability, and maintain structural integrity while complying with internal Scania requirements and relevant industry standards. The design process followed an iterative methodology starting from an analysis of the existing inverter housing and progressing through four successive design concepts. The first two concepts were developed independently, representing two fundamentally different design approaches. Concept 3 was then developed as a synthesis of the most successful features from both initial concepts, combining their respective strengths into a unified design direction. Concept 4 was subsequently developed as a refinement of Concept 3, focusing on detailed optimisation, manufacturability improvements, and structural fine-tuning. The final design was selected based on packaging efficiency, assembly feasibility, and structural performance. The structural behaviour of the inverter housing was evaluated using SimSolid. Both random vibration and quasi-static load cases were applied to assess stress distribution and deformation. A simplified load case of 1200 N applied over localized areas was used to represent severe mechanical loading conditions, including impact scenarios. The results showed that the majority of the structure remains within the defined acceptance criteria of 650 MPa von Mises stress and 1,2 mm displacement. However, the bottom region of the housing exhibited excessive deformation and was identified as the primary structural limitation of the design. The final design achieved a significant mass reduction of approximately 55% compared to the current inverter design, primarily through geometry optimisation, material reduction, and functional integration, including the cooling channel. Manufacturing was addressed through a combination of aluminium casting and CNC machining, enabling near-net-shape production with reduced assembly complexity. Overall, the project demonstrates that substantial improvements in weight and packaging efficiency can be achieved without compromising structural performance, although further validation through physical testing and detailed thermal and dynamic simulations is recommended.