  In the paper the non-linear generalization of the time blocking approximation
(TBA) is presented. The TBA is one of the versions of the extended random-phase
approximation (RPA) developed within the Green-function method and the
particle-phonon coupling model. In the generalized version of the TBA the
self-consistency principle is extended onto the phonon space of the model. The
numerical examples show that this non-linear version of the TBA leads to the
convergence of the results with respect to enlarging the phonon space of the
model.
