In English

Advanced Cooling of Electric Machine in a Hybrid Vehicle Application

Johan Fröb ; Odyssefs Lykartsis
Göteborg : Chalmers tekniska högskola, 2014. 136 s.
[Examensarbete på avancerad nivå]

Transportation sector is consuming a large portion of the total energy used by the humans. Today, most of the commercial vehicles are driven by internal combustion engines. Replacing them with electrical machine could have a large impact in the environment. But there is still room for improvement in the electric machines in order to replace the internal combustion engines. The electrical machines that are used in the automotive industry use permanent magnets in their rotors. They have a number of advantages such as very good efficiency and high power density. On the other hand, sensitivity of the magnets in high temperatures and their price is the major drawbacks of permanent magnet machines. The magnets cannot operate in high temperatures because they suffer from demagnetization. To deal with this problem, today, high temperature grade magnets with a lot of segments are used. In this thesis an oil spraying technique is used to cool the magnets in a safe operating temperature, increase their performance and also reducing their manufacturing cost. The analysis is based on theoretical calculations and experimental results from a test rig that was designed and constructed within the thesis. The oil-spraying cooling system, was designed to spray oil on the inside of the rotor of the electrical machine. Due to the high rotational speed the oil forms a thin film that absorbs the heat generated by the magnets. In the thesis a cylinder with an external heat source that simulated the actual rotor was used for evaluation. The actual losses of the magnets in an electrical machine was calculated for different operation points and segmentation of the magnets. Then the temperature of the magnets was calculated, by developing a thermal model, with and without oil spraying. The results showed significant drop in the temperature of the magnets as well as reduction in the number of segments.

Publikationen registrerades 2015-02-06. Den ändrades senast 2015-12-10

CPL ID: 212243

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