  N=2 supersymmetric field theories in two dimensions have been extensively
studied in the last few years. Many of their properties can be determined along
the whole renormalization group flow, like their coupling dependence and
soliton spectra. We discuss here several models which can be solved completely,
when the number of superfields is taken to be large, by studying their
topological-antitopological fusion equations. These models are the CPN model,
sigma models on Grassmannian manifolds, and certain perturbed $N=2$ Minimal
model.
