Environmental Engineering Reference
In-Depth Information
Fig. 5.18
Demagnetization curves of aNdFeB magnets material [VAC]
B
r
= 1
,
13 T
,
H
c
= 860 kA
/
m
,
(
BH
)
max
= 240 kJ
/
m
3
, but a maximum temperature
of 200
◦
C specified for application.
An example of a PM machine is illustrated in Fig. 5.19 where part (a) is the quad-
rant II representation of the
B
(
H
) characteristic; note the demagnetization curve at
20
◦
C and 120
◦
C and the magnetic circuit characteristic drawn as straight shearing
lines for no-load and tracking the armature reaction at short-circuit into account.
Part (b) of the figure shows the calculated field pattern of a machine with eight
poles; note the magnet supports for 2 half-poles each [Stie00].
It is understood that the performance of permanent magnet synchronous ma-
chines is characterized by constant excitation, due to the fixed pole flux value.
a)
b)
Fig. 5.19
PMSM characteristics (
a
) Magnetization; (
b
) field line pattern
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