Vector Control of an Induction Machine
ture Encoder Counter block, which converts the orthogonal digital pulses.
Rotor-field oriented control is applied to the drive system and the basic structure is shown in Fig. 3,
where the stator current is regulated in the dq frame.
U(I)
Vdc
Analog
In
Is
Analog
In
100
Te
PI
Idq*
Vs* Idq
ωe
ψr esti.
Is
θe
ωe
ωm
Idq
θ
c
ω
2 s
Enc.
Count
sw
PWM
Out
0.3
ψr*
Transform
|ψr*|
Te*
Iq*
Id*
*
/
0.5
dq
abc
Figure 3: Controller model of the induction machine drive system
Fig. 4 shows the equivalent circuit of the induction machine in the dq frame, which rotates syn-
chronously with the rotor flux. The values of
L
M
,
L
σ
S
and
R
R
are calculated from the original machine
parameters, which can be found in the initialization commands of the model, (see Note above in Sec-
tion 1).
V
sd
L
M
R
R
R
s
R
s
R
R
I
Md
V
sq
Figure 4: Equivalent circuit of the induction machine in the dq frame
The PI controllers for the d and q axis currents are included in the subsystem “PI”, as shown in Fig. 5.
The proportional and integral gains are designed following the “Optimum Magnitude” method, which
is described in more detail in the “Boost Converter” demo model of the RT Box Target Support Pack-
age..
Idq*
Vs*
Idq
ωe
+
−
K
Lσ
+
−
+
+
*
*
d-axis
i
o
q-axis
i
o
i
o
K
Kp
K
Ki
1/s
+
+
+−
K
+−
Figure 5: PI controller in the dq frame
3
