Electric Vehicles En-Route Charging Navigation Systems: Joint Charging and Routing Optimization

Widely recognized as an excellent solution of global warming and oil crisis, electric vehicles (EVs), however, suffer remarkable weakness, such as the limited cruise range, which can be partly addressed by introducing en-route charging navigation systems. Different from traditional navigation, which solves a shortest path problem, the en-route charging navigation resorts to a joint charging and routing optimization. In this brief, we formulate the en-route charging navigation in a dynamic programming setting in both a deterministic and a stochastic traffic network. Specifically, to relieve computational complexity in navigation systems, a simplified charge-control (SCC) algorithm is presented in the deterministic case, which can simplify the charging control decisions within an SCC set. In the stochastic case, an online state recursion algorithm is designed, which can provide an accurate navigation utilizing online information. Numerical simulation verifies the computing burden and accuracy of the proposed algorithms in a deterministic and a stochastic network.

I. Introduction

Electric vehicles (EVs) have been drawing much attention in recent years due to their efficiency and environmental friendliness. However, the limited cruise range, caused by the battery capacity, makes drivers in “range anxiety” especially on a long distance trip, and it makes EVs en-route charging navigation systems crucial. Since time-differentiated pricing, e.g., day-ahead pricing [1], is widely used in electricity market to shift load and stabilize power systems, an en-route charging navigation system under time-differentiated pricing is different from the traditional navigation system, where the path is both weighted by the time-dependent electricity prices and limited by the time-dependent traffic properties. This means that the routing cost is determined by not only the routing decisions but also the charging control decisions. As a result, the charging navigation becomes a joint charging and routing optimization rather than a common shortest path routing.