| Abstract [eng] |
The study of the cooling efficiency of the inverter is considered in the thesis. Inverter overheating is an extremely common problem in electric vehicles, resulting in huge losses. The cooling methods and tools used to improve the cooling efficiency of the inverter are constantly being improved by both scientists and engineers. Therefore, the purpose of this work is to investigate the cooling efficiency of the inverter at different loads. The structure of the work will consist of: literature analysis, inverter cooling study at different loads, calculations of emitted and dissipated heat quantities, results will be discussed at the end of the work and conclusions and recommendations will be prepared. After conducting a literature review and examining scientific sources, it was observed that one of the most popular cooling methods is direct cooling using a heat exchanger that is attached together with the power module. In case of ineffective cooling, more heat conductive materials are used such as: aluminum or copper, additional thermal greases for better heat transfer, heat distributors to increase the cooled area. It has also been observed that new types of heat exchangers or conceptual cooling methods are being developed that offer promising cooling characteristics. To carry out the research, a test bench was assembled, replicating the layout of the components in the electric car. During the test, the maximum output current in the driving motor inverter was determined and the output current of the braking motor inverter was changed, thus simulating a changing load. During the investigation, it was found that only in the first test, the inverter was cooled efficiently, and in all the remaining tests, the tendency of overheating of the inverter power module was visible. The results of the last test showed that the cooling system of the inverter is able to dissipate only 45% of the amount of heat emitted by the power module. According to the obtained results, it is concluded that the existing cooling of the inverter is ineffective. Recommendations for improving the cooling efficiency of the inverter: increase the coolant flow within the manufacturer's instructions, and investigate the effect of different composition of coolant on the amount of dissipated heat. Since the parameters and algorithms determined by the inverter have a great influence on the heat losses, it is suggested to conduct a study using different motor control algorithms, to evaluate the differences in the released heat quantities. |
