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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Modeling and control modes <strong>of</strong> PM synchronous motor drives<br />
For the PM synchronous motor the amplitude <strong>of</strong> stator flux<br />
Ψ<br />
s<br />
is established by<br />
permanent magnet. Operation <strong>with</strong> stator flux amplitude belong the nominal value <strong>of</strong><br />
rotor flux amplitude<br />
Ψ<br />
PM<br />
increases the amplitude <strong>of</strong> stator phase current. Please note<br />
that maximum amplitude <strong>of</strong> the stator current vector is calculated as:<br />
higher value may damage the PM (complete demagnetization).<br />
I<br />
s<br />
Ψ<br />
≤<br />
L<br />
PM<br />
d<br />
, and<br />
From the Fig. 2.8 it can be observed that rated torque is achieved for torque angle<br />
0< < 25 <br />
electrical degree.<br />
δ Ψ<br />
e[ ] M Nm<br />
M<br />
er<br />
[ Nm ]<br />
M<br />
es<br />
[ Nm ]<br />
δ Ψ<br />
[deg]<br />
Figure 2.8. Variation <strong>of</strong> synchronous torque M es<br />
, reluctance torque M<br />
er<br />
and resultant<br />
torque M as a function <strong>of</strong> torque angle (for constant stator flux equal value <strong>of</strong> PM).<br />
e<br />
2.1.3 Mechanical motion equation<br />
The equation <strong>of</strong> rotor motion dynamics describes the mechanical equilibrium <strong>of</strong> a drive<br />
system. Taking the moment <strong>of</strong> inertia to be constant ( J = const.<br />
) and neglecting friction<br />
and elastic torque we can write:<br />
where,<br />
M<br />
e<br />
= Ml + Md<br />
(2.59)<br />
Ml<br />
is the external torque on the motor shaft, and<br />
M<br />
dΩ<br />
dt<br />
where: J is total moment <strong>of</strong> inertia,<br />
M<br />
d<br />
the dynamic torque<br />
m<br />
d<br />
= J<br />
(2.60)<br />
Ω<br />
m<br />
angular speed <strong>of</strong> the rotor.<br />
22