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

Direct Torque Control with Space Vector Modulation
The torque control loop should be as fast as possible even with some overshoot. This improve
response to disturbance (for example from flux control loop –see Fig. 5.38).
M
e_ ref( z)
C ( ) M
z
U sy
Dz ( )
z −1
G ( ) M
z
}
AM
s
ZOH
2
s + B s+
C
M
M
M ( ) e
z
Figure 5.38. Block diagram of torque controller in discrete domain with disturbance.
a )
b)
Figure 5.39. Disturbance rejection in torque control loop: a) short voltage impulse, b) voltage
step.
To improve reference tracking performance (without any overshoot) it is recommended to
insert a input prefilter (see Fig. 5.40 ) described by transfer function:
z−b z−b z−0.6663
PM
( z)
= K = K = K
(5.80)
K
pM ( z−a) z−0.855
( z − )
K + K
pM
iM
Where:
K
1
=
=0.43413 is gain of the prefilter.
z − 0.6663
lim
z→1
z − 0.855
104