  Time-delay autosynchronization (TDAS) can be used to stabilize unstable
periodic orbits in dynamical systems. The technique involves continuous
feedback of signals delayed by the orbit's period. One variant, ETDAS, uses
information further in the past. In both cases, the feedback signal vanishes on
the target periodic orbit and hence the stabilized periodic orbit is one of the
original dynamical system. Furthermore, this control method only requires the
knowledge of the period of the unstable orbit. The amount of feedback gain
needed to achieve stabilization varies with the bifurcation parameter(s) of the
system, resulting in a domain of control.
  In this paper we compute the domain of control of the unstable periodic
orbits of the \textit{buck} converter. We obtain a closed analytical expression
for the curve $g:S^1 \rightarrow\C$ whose index determines the stability, and
this index is then numerically computed. We run several simulations of the
controlled system and discuss the results.
