Sirui Liu

   MSc. Sustainable Matrials - Polymer Science from Albert-Ludwigs-Universität Freiburg in Germany and University of Strasbourg in France.

   I worked with organic photovoltaic cells and designing hygroscopic bioplastic products stable in climates with a varying humidity, as illustrated for a model protein material in master degree.

   My current research focuse on Plastics in Electric Machines: aging mechanisms and the development. The transition to a society with electrical vehicles requires improved power and long-term reliability of the electrical machine. A key component to improve is the plastic insulation around copper wires and other electrical components. The project aim to study aging mechanisms in plastic insulation under conditions similar to real service life.

   A more sustainable society combatting climate changes requires that more and more vehicles are equipped with battery-fueled electric machines/motors. For a complete change the power of the motor needs to be increased and the reliability and long-term properties also needs to be improved. A bottle-neck in the performance of the motor, and to reach higher power, is the properties of the plastic insulation covering the copper wires and other plastic parts in the machine. During service, especially the insulation is exposed to high temperature, oxygen, moisture and oil, which leads to component ageing through oxidation and/or hydrolysis. A failing insulation leads to corrosion of the copper wire and eventually electric short cuts.To be able to improve the wire insulation and improve the machine performance, knowledge needs to be obtained on how the local environment affects and age the insulation as well as other plastic parts. This is an important part of the project, which will enable an optimized choice of the plastic components, oil-additives and cooling system. Part of the project will be to set up a lab scale equipment that allows for efficient and accelerated testing of the plastic components (including the wire insulation) in relevant machine environments. The project will also involve scale-up testing in a small machine/prototype motor. A specific work package will focus on involving biobased plastic and oil in the future electric machine.The project constellation is put together with companies from every important tier level; one producing passenger vehicles (Volvo Personvagnar), one producing commercial vehicles (Scania CV, trucks and buses), plastic producer (Solvay), and a producer of transmission oil (Lubrizol). The wire insulation material is obtained from Solvay.