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

Voltage source PWM inverter for PMSM supply
Next from
U
ref
, α
ref
it is necessary to calculate the time interval for particular vectors.
U 2
U ref
120°- α
UU
0, 7
t 0
t 2
α ref
t 1
Using the low of sine it is possible to write:
U 1
120°
Figure 3.18 One sector in voltage plane.
U
ref U1 U2
= =
sin120° sin(60 °−α
) sinα
ref
ref
(3.12)
From this relations calculated value of vectors
sin(60 °−αref
) 2
U1
= Uref = Uref sin(60 °−αref
)
sin120°
3
(3.13a)
sin
ref 2
U2
= U α = U
sin120°
3
sinα
ref ref ref
(3.13b)
and respectively the normalized times are given:
3 U
1
ref
1
= = sin(60 °− αref
)
(3.14a)
2
U
U
DC
DC
t
3
U
3 U
2
ref
2
= = sinα
ref
(3.14b)
2
U
U
DC
DC
t
3
U
Putting Eq. (3.13a-b) in to Eq. (3.14a-b) the normalized value can be presented as:
2 3
t1
= Msin(60 °− α ref
)
(3.15a)
π
2 3
t2
= Msinα
ref
(3.15b)
π
or in other form:
48