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

Voltage source PWM inverter for PMSM supply
time”. It guarantees safe operation of the inverter. The typical value is from 1µ s - 5µ s .
When the lowest value is for small power IGBT and is growing in respect to increasing
of IGBT power. More details about real IGBT module you can find in Appendices.
The effect of dead time can be examined from one phase of PWM inverter. The basic
configuration is shown in Fig. 3.9. Consist of upper and lower power devices T
1
and T
2
,
and reverse recovery diodes D
1
and D
2
, connected between the positive and negative
rails of power supply. The gating signals S
A
and S
Ai
come from control block. Output
voltage terminal U
0
is connected to motor phase.
S A
T 1
D 1
U DC
I sA
S Ai
T 2
D 2
LOAD
U 0
S
Dead time
Td
Figure 3.9 Circuit diagram of one inverter leg.
Fig. 3.10 shows the ideal control signals and real control signals with inserted dead time
T
d
. As can be observed the time duration of real drive signal for upper transistor is
shorted than ideal drive signal and for lower transistor is longer than ideal.
Ideal drive signals
Real drive signals
S A
S A
T d
S Ai
S Ai
T d
Figure 3.10 Gate signals control of one inverter leg.
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