MDO (multidisciplinary design optimization) and FSI (fluid-structure interaction)
Title: MDO (multidisciplinary design optimization) and FSI (fluid-structure interaction)
DNr: NAISS 2023/5-197
Project Type: NAISS Medium Compute
Principal Investigator: Zhiyuan Li <>
Affiliation: Chalmers tekniska högskola
Duration: 2023-04-26 – 2024-05-01
Classification: 20306


Electrification of vehicles has a good momentum today. However, the energy consumption of electrified vehicles is not very much in focus, instead, in-efficient electrified vehicles are appreciated on the cost of more energy-efficient ICE vehicles. There is talk about a ‘nordic energy mix’, but still almost every single extra kWh of electric energy put in an electrified vehicle in Scandinavia must be generated by fossil fuels. This needs to come to an end when electrified vehicles become more and more common. In a recently conducted research project [Vehicle – Energimyndigheten project 41213] it was identified that the gearbox has the same loss as the electrical machine. The gearbox is usually a two-stage gearbox, with a gear ratio of 8-12. If a single-stage gearbox could be used, the efficiency would go up, however, then the electric machine becomes larger. No gear at all gives best efficiency, but a very large electrical machine. In principle, 1500 rpm at top speed with a power of 100-150 kW is what is needed. The purpose of this project branch is to optimize the electric machine-gear package to find a system solution that has the highest efficiency, but still reasonable size. The hypothesis is that by a careful design of the gearbox, selection of more viscous oil, but still suitable to maintain the lifetime of the gear in combination with an adapted machine design will lead to important loss savings in the transmission of an electrified vehicle. A set of base electrical machines will be identified, focusing on environmentally sound machines without rare earth metals. For a given requirement (100 kW) veracious electric machines will be designed and the outcome will be communicated to the Fluid Dynamics division. Based on the feedback from their side modifications will take place