Environmental Engineering Reference
In-Depth Information
the number of current sensors, a 3-phase winding was selected for both config-
urations, that is
m 12 ¼ m 4 ¼ 3
ð 5 : 30 Þ
The phase belts for 12-pole and 4-pole configurations are consequently:
q 12 ¼ 2,
q 4 ¼ 6
ð 5 : 31 Þ
Before presenting the complete winding diagram, it is useful to define
the elementary machine coil and the coil polarity as illustrated by referring to
Figure 5.43.
Coil #
71
72
1
2
+
+
+
+
Figure 5.43 Schematic representation of elementary coils in a toroidally wound
machine. All coils are wound in the same directions; the front end of
the coil is designated as ( þ ); the back end is ( ). Each winding is
obtained by connecting coils as in Figure 5.45
It is important to recall that in a toroidal machine, each coil side in the airgap
conducts current in one direction only as denoted in Figure 5.43. To obtain the
same effect as in a standard IM (where each coil conducts the current axially in
both directions; see Figure 5.44), here, two elementary toroidal coils are connected
in series. These two coils then form a coil group, so that the number of coil groups
(i.e. effective coils) in a 72-slot machine is 36.
Figure 5.44 Schematic representation of a conventional coil. The current flows in
both directions - compare with toroidal coil connection, as shown in
Figure 5.43
One possible winding connection, for a 3-phase toroidal machine, which satis-
fies all requirements, is shown in Figure 5.45. Coils #1 and #2, #19 and #20, #55 and
#56 form one branch etc. The top point of each branch ( þ 1, þ 21, þ 5, þ 25, þ 9, þ 29,
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