Energy Management System for an Electric Vehicle with a Rental Range Extender: A Least Costly Approach

Range extenders (REs) increase the driving range of electric vehicles (EVs) at the price of additional weight and encumbrance, which are unnecessary in normal urban usage. An innovative concept of an extended range EV is studied here, i.e., an EV that can exploit a rental RE only when necessary to complete a mission. The energy management system not only dispatches power between a battery and an RE but also decides whether or not and when to rent the RE. This paper investigates the optimal control policy that minimizes the monetary cost attained by the user. A simulation analysis carried out in a representative set of scenarios demonstrates the interest of this formulation and shows that mixed-integer convex programming (MI-CP) attains high accuracy in a fraction of the time required by dynamic programming, with a negligible loss of performance. In a real-time framework, the MI-CP core is fed by a forecast of the mission and integrated with a power dispatch strategy that optimizes local performance. The simulation study shows that the resulting policy approaches the global optimum.