Marvel Studios head Kevin Feige recently spoke with MTV News about "Iron Man 3" and discussed both Tony Stark's psyche and the various versions of the armor we'll see in the film.
"It's almost like post-traumatic stress: he has retreated after the events of 'The Avengers' into his workshop, where he's building advanced versions of his suits. He has [designed] a version of the suit that can latch onto him in individual pieces ... anytime, anywhere.
He starts to realize [that] he doesn't want to be out of the suit. He's seen a lot of things in 'Avengers' and has encountered a lot of powerful people, much more powerful than he is.
Much of the movie is Tony in the middle of the country without his tools and a fairly broken suit to help him. But that's his superpower: his power is his brain. It's fun to put Tony Stark in a corner with nothing and see how he can get out of it."
Source: MTV News