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

Direct Torque Control with Space Vector Modulation
• increment of torque angle ∆δ Ψ
coming from torque control loop (see Fig.5.2.) is equal
zero. It means that the torque is not produced,
• stator flux vector position θ Ψ s
and rotor flux vector position θ r
are equal zero. It
corresponds to situation, where the those two flux vectors lie along the α axis.
In this special case the reference stator flux amplitude Ψ
_
=Ψ
α _
can be controlled
s ref s ref
trough the reference stator voltage component U
α _
= U
_
, when the voltage drop on the
s ref s ref
stator resistances in α,
β axes are neglected (see Fig. 5.5). Therefore, the simplified flux
control loop can be shown in Fig. 5.6.
Ψ =Ψ α
s _ ref s _ ref
s sα
Ψ =Ψ
−
∆Ψ sα
controller
P
U
sα _ ref
= Us _ ref
U β
=
s _ ref
0
PMSM
Ψ sα
Ψ sβ
Continuous s-domain
Figure 5.6. Simplified flux control loop in α,
β coordinates.
Simplified flux control loop in s domain is shown in Fig. 5.7, where CΨ ( s)
is a transfer
function of the P controller given by:
CΨ() s = KpΨ
(5.11)
The transfer function between stator flux amplitude Ψ
s
=Ψ sα and stator voltage amplitude
U
s
can be expressed as:
G
Ψ
Ψ
s 1
() s = = (5.12)
U s
s
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