The winding of an in-wheel electric motor is water sensitive. Epoxy resin, with which the stator of an in-wheel motor is casted, is prone to cracking. The crack allows water to access the winding. In case water reaches the winding, an electrical breakdown occurs, that causes the engine to malfunction. To prevent water from entering into the cracks, the stator is wrapped with external protection. The purpose of the thesis is to determine all requirements needed to perform foil wrapping of the stator. We tested two different types of foil. For the steel foil we determined the proper glue for the application, curing parameters of the glue and prestressed the foil. We evaluated the results by open circuit measurements, where we focused on the induced eddy current losses. For the polymer heat shrinking foil we determined the surface preparation of the stator, the addition of epoxy glue, the compressive force in form of a stator mold and the curring parameters of the glue. We tested the foil with a heat shock test, where we observed interactions between different stator materials. The results for the steel foil showed that the wrapping process is very demanding, but on the other hand the eddy current losses were still manageable. The polymer heat shrinking foil proved to be a better choice, the compressive force ensured good adhesion between the foil and the stator. The testing results didn't show larger irregularities, the foil wasn't damaged and passed the test.
|
