  We study an online reservation system that allows electric vehicles (EVs) to
park and charge at parking facilities equipped with electric vehicle supply
equipment (EVSEs). We consider the case where EVs arrive in an online fashion
and the facility coordinator must immediately make an admission or rejection
decision as well as assign a specific irrevocable parking spot to each admitted
EV. By means of strategic user admittance and smart charging, the objective of
the facility coordinator is to maximize total user utility minus the
operational costs of the facilities. We discuss an online pricing mechanism
based on primal-dual methods for combinatorial auctions that functions as both
an admission controller and a distributor of the facilities' limited charging
resources. We analyze the online pricing mechanism's performance compared to
the optimal offline solution and provide numerical results that validate the
mechanism's performance for various test cases.
