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

Direct Torque Control with Space Vector Modulation
It corresponds to the transfer function of closed stator flux control loop:
G
C
0.2688
( z)
= =
z − z+ C z −z+ 0.2688
Ψd
Ψ _ closed
2 2
Ψd
(5.54)
Using digitalized motor parameters A
can calculate the parameters of digital PI flux controller as:
Ψd
− AΨT (1 − e s
)
− A Ts
= , BΨ d
e Ψ
A
= and chosen C Ψ d
value, we
Ψ
K
pΨ
C B
A
Ψd
Ψd
= (5.55a)
Ψd
T
iΨ
K
T
pΨ
s
= (5.55b)
K
iΨ
K
iΨ
K
pΨ
= (1 − BΨd)
(5.55c)
B
Ψd
For example with sampling time T = 200µ
s, parameters of PI controller are:
s
K
pΨ
0.2688BΨd
0.2688*0.9772
= = = 1328.64
(5.56a)
A 0.0001977
Ψd
T
iΨ
KpΨTs
1328.64*200µ
s
= = = 8572µ
s
(5. 56b)
K 30.999
iΨ
K
iΨ
K
pΨ
1328.64
= (1 − BΨd) = *(1-0.9772) = 30.999 (5. 56c)
B
0.9772
Ψd
For different sampling time the closed transfer function GΨ _ closed
( z)
of digital flux control
loop should be kept to:
G
C
0.2688
( z)
= =
z − z+ C z −z+ 0.2688
Ψd
Ψ _ closed
2 2
Ψd
(5.57)
In order to find the original function of Z transfer function GΨ _ closed
( z)
using the Z properties
as (sum transformations) [2]:
n
z
z
∑ f kT Z F z Z G z
k = 0
z−1 z−1
−1
z a
= Z [ ]
2
z−1( z − z+
a)
−1 −1
(
s) = [ ( )] = [
Ψ _ closed( )]
(5.58)
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