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

Sensorless Speed Direct Torque Control with Space Vector Modulation (DTC-SVM)
The first part of the equation represents a LP filter. The second part realizes a feedback,
which is used to compensate the error in the output. The block diagram of new
integration algorithm with saturation block is shown in see Fig. 6.11.
I sA
ABC
Is
α
I sB
αβ
Is
β
R s
ωc
s +ω
c
Y lim
− lim
lim
U sA
U sB
ABC
αβ
U
s α
U
s β
R s
Es
α
Es
β
1
s + ω c
1
s + ω c
Ψ α _ comp
Ψ s α
Ψ sβ
Ψ s
θ Ψs
Ψ
s β _ comp
ωc
s +ω
c
Y lim
− lim
lim
Figure 6.11. Full block diagram of voltage model based estimator with saturation block on the
α,
β components.
The main task of saturation block is to stop the integration when the output signal
Ψ
sα
or
Ψ
sβ
exceed the reference value of stator flux amplitude. Please note that if the
compensation signal is set to zero, the improved integrator represents a first-order LPfilter.
If the compensation signal
integrator operates as a pure integrator.
Ψ or Ψ
β _
is not zero the improved
sα
_ comp
s
comp
Discrete time implementation of the improved integrator becomes:
ω
zΨ ( z) =Ψ ( z) + ( U − R I ) T + ( Ψ ( z) −Ψ ( z))
(6.16)
c
sα sα sα s sα s sα _lim
sα
Ts
ω
zΨ ( z) =Ψ ( z) + ( U − R I ) T + ( Ψ ( z) −Ψ ( z))
(6.17)
c
sβ sβ sβ s sβ s sβ _lim
sβ
Ts
The output of saturation block can be described as:
⎧Ψ
sαβ
( z) if (Ψ
sαβ(z))=lim
sαβ
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