This is a real good concept. I love the unique design and the cartoons look as good as the movie.
In 1991, they actually did make a Back to the future animated series. it was kinda goofy, but pretty funny.
In the series Doc Brown was voiced by Dan Castellaneta (aka Homer Simpson) but it did have Christopher Lloyde as Doc in the live action segments at the end of the episode.
But I like your design much better. It fits the characters perfectly. great job.