
3-26 Power Electronics and Motor Drives
Mechanical equation of motion of (3.7) is of course the same as for an induction machine. Relationship
b
etween
o
riginal
s
tator
p
hase
v
ariables
a
nd
t
ransformed
s
tator
d
−
q
a
xis
q
uantities
i
s
i
n
t
he
g
eneral
c
ase
a
nd in the three-phase case governed with (3.25) and (3.24), respectively, where
θ θ ω
s
dt≡ =
.
3.8.3 Permanent Magnet Synchronous Machines
Since in permanent magnet synchronous machines eld winding does not exist, the eld winding equa-
tions
(
(3.41c)
a
nd
t
he
l
ast
o
f
(
3.42))
a
re
o
mitted
f
rom
t
he
m
odel.
I
t
i
s
a
lso
o
bserved
t
hat
t
he
p
ermanent
m
agnet
ux
ψ
m
now replaces term L
md
i
f
in the ux linka