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

Direct Torque Control with Space Vector Modulation
increment required to minimize the instantaneous error between reference
M and actual
e_
ref
M
e
torque.
In control scheme of Fig. 5.2 the torque error signal e M
is delivered to the PI controller,
which determines the increment of torque angle
∆ δ Ψ
. Based on this signal and reference
amplitude of stator flux
Ψ , the reference voltage vector in stator coordinates α,
β is
s _ ref
calculated. The calculation block of reference voltage vector also uses information about the
actual stator flux vector (amplitude
Ψ
s
and position θ Ψ s
) as well as measured current vector
I
s
. The reference stator voltage vector is delivered to space vector modulator (SVM), which
generates the switching signals
S , S , S for power transistors of inverter.
A
B
C
The calculation block of reference voltage vector is shown in Fig. 5.3.
Ψ s _ ref
RsI s α
Ψ
s α _ ref
∆Ψ sα
U α
_
s
_ ref
∆δ Ψ
−
Ψ
s β _ ref
∆Ψ sβ
−
U
s β ref
θ Ψs
Ψ sα
Ψ sβ
Rs
Is
β
Figure 5.3. Calculation block of reference voltage vector.
Based on
∆ signal, reference of stator flux amplitude Ψ
s _ ref
and measured stator flux
δ Ψ
vector position
θ Ψ s
(Fig. 5.3.), the reference flux components
Ψ Ψ in stator
s α _ ref
,
sβ
_ ref
coordinate system are calculated as:
Ψ = Ψ cos( θ +∆δ
)
sα
_ ref s_
ref Ψs
Ψ = Ψ sin( θ +∆δ
)
sβ
_ ref s _ ref Ψs
Ψ
Ψ
(5.4)
Pleas note that for constant flux operation region the reference value of stator flux amplitude
Ψ is equal flux amplitude of permanent magnet Ψ
PM
.
s _ ref
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