Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...
Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...
Direct Torque Control with Space Vector Modulation (DTC-SVM) of ...
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<strong>Direct</strong> <strong>Torque</strong> <strong>Control</strong> <strong>with</strong> <strong>Space</strong> <strong>Vector</strong> <strong>Modulation</strong><br />
increment required to minimize the instantaneous error between reference<br />
M and actual<br />
e_<br />
ref<br />
M<br />
e<br />
torque.<br />
In control scheme <strong>of</strong> Fig. 5.2 the torque error signal e M<br />
is delivered to the PI controller,<br />
which determines the increment <strong>of</strong> torque angle<br />
∆ δ Ψ<br />
. Based on this signal and reference<br />
amplitude <strong>of</strong> stator flux<br />
Ψ , the reference voltage vector in stator coordinates α,<br />
β is<br />
s _ ref<br />
calculated. The calculation block <strong>of</strong> reference voltage vector also uses information about the<br />
actual stator flux vector (amplitude<br />
Ψ<br />
s<br />
and position θ Ψ s<br />
) as well as measured current vector<br />
I<br />
s<br />
. The reference stator voltage vector is delivered to space vector modulator (<strong>SVM</strong>), which<br />
generates the switching signals<br />
S , S , S for power transistors <strong>of</strong> inverter.<br />
A<br />
B<br />
C<br />
The calculation block <strong>of</strong> reference voltage vector is shown in Fig. 5.3.<br />
Ψ s _ ref<br />
RsI s α<br />
Ψ<br />
s α _ ref<br />
∆Ψ sα<br />
U α<br />
_<br />
s<br />
_ ref<br />
∆δ Ψ<br />
−<br />
Ψ<br />
s β _ ref<br />
∆Ψ sβ<br />
−<br />
U<br />
s β ref<br />
θ Ψs<br />
Ψ sα<br />
Ψ sβ<br />
Rs<br />
Is<br />
β<br />
Figure 5.3. Calculation block <strong>of</strong> reference voltage vector.<br />
Based on<br />
∆ signal, reference <strong>of</strong> stator flux amplitude Ψ<br />
s _ ref<br />
and measured stator flux<br />
δ Ψ<br />
vector position<br />
θ Ψ s<br />
(Fig. 5.3.), the reference flux components<br />
Ψ Ψ in stator<br />
s α _ ref<br />
,<br />
sβ<br />
_ ref<br />
coordinate system are calculated as:<br />
Ψ = Ψ cos( θ +∆δ<br />
)<br />
sα<br />
_ ref s_<br />
ref Ψs<br />
Ψ = Ψ sin( θ +∆δ<br />
)<br />
sβ<br />
_ ref s _ ref Ψs<br />
Ψ<br />
Ψ<br />
(5.4)<br />
Pleas note that for constant flux operation region the reference value <strong>of</strong> stator flux amplitude<br />
Ψ is equal flux amplitude <strong>of</strong> permanent magnet Ψ<br />
PM<br />
.<br />
s _ ref<br />
67