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

Voltage source PWM inverter for PMSM supply
Compensation
block
IsA
IsB
Compensation of
inverter
I sC
U DC
T comp
U α _comp
U β _comp
*
U α _ideal
*
U β _ideal
*
U α _ real
*
U α _ real
*
U β _ real
PWM
Modulator
S
A
S B
S C
Inverter
*
U β _ real
U α _out
U β _out
I α _out
I β _out
Load
Figure 3.14 Block diagram illustrating the dead time and voltage drop across power devices
compensation method in three phase motor supplied from non-ideal voltage source inverter.
In order to compensate the inverter non-linearity to the ideal reference voltage
*
components in stationary reference frame ( U α
,
(
_ comp
_ ideal
*
U β _ ideal
) a compensation signal
U α
, U β _ comp
) is added. As a consequence the real reference voltage components
*
( U α
,
_ real
*
U β _ real
) are pre-distorted. Further those signals are delivered to PWM
modulator with non-ideal inverter. As a result the output voltages are not distorted in
Fig. 3.14 and thus phase currents in the load (red signals in Fig. 3.14) are almost
sinusoidal.
To calculate an average compensation voltages ( U α _ comp
, U β _ comp
), the parameters of
IGBT modules as:
• dead time T
d
,
• turn on T
ON
and turn off T
OFF
of IGBT transistors,
• and also on a voltage drop on diode V
D
and transistor
should be know.
V
T
,
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