Evaluation of Eddy Current Losses in the Cooling Sleeve of a Toroidal High Speed Permanent Magnet Machine

Thanks to the development in fields of materials and power electronics, the use of high speed electrical machines has boosted significantly in recent decades due to their many advantages and applications. To enhance this king of machines, it is absolutely necessary to reduce losses. This is especially applicable to eddy current losses. Their evaluation in the cooling sleeve of a toroidal high speed permanent magnet machine in this paper has been performed through 2D analytical harmonic model implemented in Matlab, 2D FEM model implemented in Cedrat Flux software and laboratory tests. The final goals have been to obtain a validated model to estimate eddy current losses and determine experimentally if the segregation of losses method is applicable to the considered problem. Two different materials, copper and aluminum, have been analyzed changing their thickness and varying the airgap between the external part of stator coils and cooling sleeve. The results show how electrical conductivity, frequency and geometry influence eddy current losses.