  We analyze the equilibrium micromagnetic domain wall structures encountered
in Permalloy strips of a wide range of thicknesses and widths, with strip
widths up to several micrometers. By performing an extensive set of
micromagnetic simulations, we show that the equilibrium phase diagram of the
domain wall structures exhibits in addition to the previously found structures
(symmetric and asymmetric transverse walls, vortex wall) also double vortex and
triple vortex domain walls for large enough strip widths and thicknesses. Also
several metastable domain wall structures are found for wide and/or thick
strips. We discuss the details of the relaxation process from random
magnetization initial states towards the stable domain wall structure, and show
that our results are robust with respect to changes of e.g. the magnitude of
the Gilbert damping constant and details of the initial conditions.
