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

Direct Torque Control with Space Vector Modulation
5.3 Parallel structure of DTC–SVM scheme
Block scheme of the control structure is shown in Fig. 5.25. Two PI controllers are used for
regulation torque and flux magnitude loops [11,55].
U DC
Ψ s _ ref
e Ψ
ss
U sx _ ref
s
_ ref
S A
S B
M e _ ref
e M
U sy _ ref
U α
U
s β _ ref
S C
θ Ψs
Ψ
I s
M e
γ
m
Figure 5.25. Parallel structure of DTC-SVM scheme.
In this control scheme the reference stator flux magnitude
Ψ and reference
s _ ref
electromagnetic torque
M are compared with estimated values, respectively. The flux and
e_
ref
torque errors eΨ , e are delivered to PI controllers, which generate command value the stator
s
M
voltage components in stator flux coordinates
U , U
_
sx_
ref
sy
ref
. This voltage signals are
transformed to stationary coordinates using the stator flux position angle θ Ψ s
. The reference
stator voltage vector ( U
s α _ ref
, U
s β _
ref
) is delivered to space vector modulator (SVM), which
generates the switching signals
S , S , S to control power transistors of the inverter.
A
B
C
The presented control strategy is based on simplified stator voltage equations described in
stator flux oriented x-y coordinates (equations 2.27a-b):
U
d
Ψ
s
sx
= Rs Isx
+ (5.37)
dt
U = R I +Ω Ψ = R I + E = k M + E
(5.38)
sy s sy Ψs s s sy sy s e sy
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