
25-16 Power Electronics and Motor Drives
In the direct structure (Figure 25.16a), some diculties occur with the direct adjustment of the con-
troller parameter based on the error e
c
(k), as this error is not directly accessible at the NN output and
cannot be used for the corrections calculation of NN weight factors. It is especially dicult in the case
of nonlinear plants, as their description (transfer function) is not known or changing with respect to
the operation point. Nevertheless, with the assumption, that the plant is described by certain func-
tion f
p
(u(k)), the backpropagation method can be only used, if the derivative
′
f u k
p
(