Life Length and Stress Tests of Electric Machines for Electric Vehicles

• Main Author: Sanz Desco, Raul
• Format: Others
• Language: English
• Published: KTH, Skolan för kemivetenskap (CHE) 2017
• Subjects: Electrical machines; winding insulation; power cycling; thermomechanical stresses; winding cooling; Polymer Technologies; Polymerteknologi
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-214554

Electrical machines have been widely used along the last decades with large life length under operating conditions. However, they will become more important in the upcoming years because of the emerging electric car industry. Thus, the maintenance cost of this technology can be reduced by extending the lifetime in the electrical machines. Despite the fact that existing numerous studies within the life length in these devices, only few study the effect of the thermomechanical stresses of insulation. The core of this master thesis is to study the influence of these stresses in the insulation material of a winding. The tested electrical machines were subjected to different test conditions, allowing to analyse multiple aging effects in the winding. To achieve these effects, power cycling tests were carried out on stators, where the windings were tested in cycles with different ΔT and two cooling methods: air cooling and oil cooling. The results showed large aging differences between the two cooling methods employed. The aging effect in the oil cooling method was higher than in the air cooling method for the same number of cycles. However, the aging effects regarding the same cooling process had not wide differences between the different test temperatures.