  This paper investigates battery preheating before fast charging, for a
battery electric vehicle (BEV) driving in a cold climate. To prevent the
battery from performance degradation at low temperatures, a thermal management
(TM) system has been considered, including a high-voltage coolant heater (HVCH)
for the battery and cabin compartment heating. Accordingly, an optimal control
problem (OCP) has been formulated in the form of a nonlinear program (NLP),
aiming at minimising the total energy consumption of the battery. The main
focus here is to develop a computationally efficient approach, mimicking the
optimal preheating behavior without a noticeable increase in the total energy
consumption. The proposed algorithm is simple enough to be implemented in a
low-level electronic control unit of the vehicle, by eliminating the need for
solving the full NLP in the cost of only 1Wh increase in the total energy
consumption.
