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

2. Voltage Source Inverter Fed Induction Motor Drive
few methods proposed to decouple the flux and torque control. It is achieved, for
example, by the orientation of the coordinate system to the rotor or stator flux vectors.
Both control systems are described further in Chapter 3.
The equations (2.17), (2.18), (2.19) and the block diagram presented in the Fig. 2.2
can be used to build a simulation model of the induction motor. It was used in a
simulation model, which is presented in Appendix A.2.
2.3. Voltage Source Inverter (VSI)
The three-phase two level VSI consists of six active switches. The basic topology of
the inverter is shown in Fig. 2.3. The converter consists of the three legs with IGBT
transistors, or (in the case of high power) GTO thyristors and free-wheeling diodes. The
inverter is supplied by a voltage source composed of a diode rectifier with a C filter in
the dc-link. The capacitor C is typically large enough to obtain adequately low voltage
source impedance for the alternating current component in the dc-link.
DC side
PWM Converter
U dc
2
U dc
2
0
C
C
S A
+
S A
-
T 1
T 3
T 5
D S B
+
S C
+
1
T 2
D 3
D 5
T 4
T 6
D S
2
B
- D S
4 C
-
D 6
I A
I
A
U B
I C
AB B C
AC side
R A
R B
R C
L A
U A
L B
U B
L C
U C
E A
E B
E C
N
IM
Fig. 2.3. Topology of the voltage source inverter
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