Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...

Direct Torque Control with Space Vector Modulation
Assuming small changes of δ Ψ
, the cosδ Ψ
≅ 1, and equations (5.41) reduces to:
Rs
Usx
=Ψ
s
( s+ ) + WΨ
(5.42)
L
s
RsΨ
PM
Where WΨ
=
L
s
The transfer function between stator flux amplitude
Ψ
s
and x-axis of stator voltage is:
G
Ψ
Ψ
s Ls
1 1
() s = = = =
U R
sx
+ WΨ
sLs + Rs
s
s +
s+
A
L
s
Ψ
(5.43)
Where W
Ψ
Rs
Rs
≅ ΨPM
cosδΨ
≅ Ψ
L
L
s
Rs
For motor parameters (see Appendices ): A = Ψ
115.333
L
= .
s
PM
Continuous s-domain
The flux control loop is shown in Fig. 5.27, where CΨ ( s)
is a transfer function of the PI
controller given by [105]:
C
Ψ
s
⎛ K ⎞
iΨ
KpΨ
s+
⎜
K ⎟
pΨ
() s =
⎝ ⎠
(5.45)
s
where
K
iΨ
=
K
T
pΨ
iΨ
Ψ s_ref
C
Ψ
() s
U sx
W Ψ
()
Rs
Ψ
L
s
PM
cos
δ Ψ
+
G
Ψ
s
Ψ s
Figure 5.27. Block diagram of flux control loop in s-domain.
Hence, the transfer function of the closed stator flux amplitude control loop is obtained as:
90