POLITECHNIKA WARSZAWSKA

5. Speed estimation of induction motor
u s
i s
Flux Model
z -1
ψ ru
-
ε
Neural Netwok
with
Weight ^ ω m
+
ψ ri
Fig.5.10 . Block diagram of the NN based speed estimator
The discrete current model of rotor flux one can calculate from Eq.5.17.
Ψri(k) = [(1-Ts/Tr)+jωmTs/T N ]Ψ ri(k-1)+(TsxM/Tr) is(k-1) (5.18)
where Ts is the sampling time.
The model based on Eq.5.18 is similar to neural network. One weight is proportional
to mechanical speed, and the output is Ψri [130].
Ψri(k) = w 1 Ψ ri(k-1) + w 2 jΨ ri(k-1) + w 3 is(k-1) (5.19)
The error output is given by
e(k) = Ψri(k) - Ψru(k) (5.20)
Therefore, to calculate estimated mechanical speed ωm one can use back propagation
training algorithm [144].
The ANN in this case has very simple form and is presented in Fig.5.11.
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