
Permanent Magnet Synchronous Motors 6-21
per pole pair (whose ends are uniformly distributed along the rotor circumference) is related to the
n
umber of stator slots Q so that
N
Q
p
rfb
= ±
2
1
(6.24)
A
d
ierent
s
trategy
to
c
ompensate
t
he
to
rque
h
armonics
o
f
a
nisotropic
m
otors
i
s
b
ased
o
n
a
t
wo-step
d
esign procedure [27,28]:
1
.
A s
et
o
f
u
x
b
arrier
g
eometries
i
s
i
dentied
s
o
a
s
t
o
c
ancel
a t
orque
h
armonic
o
f
g
iven
o
rder.
is means that a harmonic of given order is zero according to the geometry of the rotor ux
b
arriers.
2
.
C
ouples
o
f
ux
b
arriers
b
elonging
to
t
his
s
et
a
re
c
ombined
to
gether
s
o
a
s
t
he
r
emaining
to
rque
h
armonics
o
f
o
ne
ux
b
arrier ...