The elevations 28, 29 are distanced from one another by a first arc length in a first radial position marked by a point 30. The first radial position is situated between a through-opening 31 of the end plate 25 and the collar 27, which defines a second radial position marked by a point 32. In the second radial position the elevations 28, 29 are distanced from one another by a second arc length, which is greater than the first arc length. The elevations 28, 29 thus form a substantially V-shaped part of the cooling channel portion 21, which corresponds to the arrangement of the magnet pockets 7a-7d of one of the magnet pocket arrangements 6. From the first radial position, the cooling channel portion 21 continues in a straight line as far as the through-opening 31, where the elevations 28, 29 adjoin one of the through-holes 24 (see FIG. 1).

Pairs of first fluid-guiding elements 33, second fluid-guiding elements 34 and third fluid-guiding elements 35 are provided within each cooling channel portion 21, 22 and are symmetrical with respect to a plane 36 extending in the radial direction through the middle of the cooling channel portion 21. A fourth fluid-guiding element 37 is additionally provided.

FIG. 4 is a detailed depiction of the end plate 25 with projections (shown by dashed lines) of the positions of the permanent magnets 3a-3d.