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

Direct Torque Control with Space Vector Modulation
q − axis
β
δ Ψ
Ψ s _ ref
∆δ Ψ
θ Ψ
s
Ψ s
Ψ PM
d − axis
θ r
Figure 5.1. Space vector diagram illustrating torque control conditions.
α
5.2 Cascade structure of DTC–SVM scheme
The structure of proposed control scheme is shown in the Fig. 5.2. [11,33,42,48,51,53,54]
U DC
Ψ s _ ref
U
s α _ ref
S A
S B
M e _ ref
e M
∆δ Ψ
U
s β _ ref
S C
θ Ψs Ψs
I s
M e
I s
γ m
Figure 5.2. Cascade structure of DTC-SVM scheme.
The error between reference and measured torque can be expressed as:
Ψ Ψ sin( δ +∆δ ) Ψ Ψ sinδ
eM = M − M = p
− (5.3)
3 s_
ref PM Ψ Ψ
_
[
s PM Ψ
e ref e b
]
2
Ls
Ls
From equation (5.3) we can see that the relation between torque error and increment of load
angel
∆δ Ψ
is nonlinear. Therefore, we used PI controller which generates the load angel
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