Space Vector Modulated – Direct Torque Controlled (DTC – SVM ...

2. Voltage Source Inverter Fed Induction Motor Drive
Taking into consideration the electrical circuit in Fig. 2.19 the voltage distribution
can be obtained. The voltages can be written as:
2
1
1
U A
= U dc
; U B
= − Udc
; U C
= − U
dc
(2.32)
3
3
3
1
1
1
U A0
= U dc
; U B0
= − Udc
; U C0
= − U
dc
(2.33)
2
2
2
U
N0
1
= U
A0
−U
AN
= − Udc
(2.34)
6
This analysis may be repeated for all vectors provided to obtain voltages presented in
Table 2.1.
Table 2.1. The voltages for the eight converter output vectors
U 0
U 1
U 2
U 3
U 4
U 5
U 6
U 7
U
A0
1
−
2
1
U dc
2
1
U dc
2
1
−
2
1
−
2
1
−
2
1
U dc
2
1
U dc
2
U dc
U dc
U dc
U dc
U
B0
UC0
U
A
U
B
UC
U
N0
1 1
1
− U
dc
− U dc 0 0 0 − U
dc
2 2
2
1 1 2 1 1 1
− U dc
− U dc U
dc
− U dc − U
dc
− U
dc
2 2 3 3 3 6
1 1 1 1 2 1
U dc − U dc
U dc
U dc
− U dc U
dc
2 2 3 3 3 6
1 1 1 2 1 1
U dc
− U dc − U dc
U
dc − U
dc
− U
dc
2 2 3 3 3 6
1 1 2 1 1 1
U dc
U dc
− U
dc U
dc
U dc
U dc
2 2 3 3 3 6
1 1 1 1 2 1
− U
dc
U dc
− U dc
− U dc
U
dc
U
dc
2 2 3 3 3 6
1 1 1 2 1 1
− U dc
U dc
U dc
− U dc
U
dc
U
dc
2 2 3 3 3 6
1 1
1
U dc
U dc 0 0 0 U
dc
2 2
2
The average value for sampling time of U NO voltage can be written as follows:
U
N0
1 U
dc ⎛ 1 1
= ⎜−
t0
− t1
+ t2
+ t7
T 2 ⎝ 3 3
s
⎞
⎟
⎠
for the sectors I, III, V (2.35)
and
U
N0
1 U
dc ⎛ 1 1
= ⎜−
t0
− t2
+ t1
+ t7
T 2 ⎝ 3 3
s
⎞
⎟ for the sectors II, IV, VI (2.36)
⎠
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