Theoretically speaking, one might perceive or counsel a 'duty to vote', but this is likely contingent upon an unstated assumption of a preference for liberty.

That is to say, if you have a preference for liberty, then you ought to vote.  My justification for this would be Kant's categorical imperative that one ought to "act only according to that maxim whereby you can at the same time will that it should become a universal law." 

It if no one actually votes, then our democracy will fail and we will be ruled by a dictatorship soon enough.  Ergo, if one values liberty, and one claims to be rational, then one is obliged to vote.

Note: I am of course assuming that liberty is only generally or widely available under a democratic ruled state.