Energy Management in Plug-In Hybrid Electric Vehicles: Preheating the Battery Packs in Low-Temperature Driving Scenarios

Plug-in hybrid electric vehicles (PHEVs) with large battery packs have significant advantages in improving fuel efficiency and lowering harmful emissions. However, battery charging and discharging performance degrades dramatically at low temperatures, resulting in increasing vehicle operating expenses, which hinders the deployment of PHEVs in severe cold regions. To address this challenge, this paper proposes an energy management strategy (EMS) that combines a battery preheating strategy to preheat the battery to a battery-friendly temperature before vehicle operation. This study provides three specific contributions. First, a high-precision electro-thermal-aging coupled model for a wide temperature range is developed, considering the effect of temperature on the battery's available capacity. Second, the grid-and battery-powered preheating strategies are established using a flexible polyimide heating film to preheat the batteries. Finally, the particle swarm optimization (PSO) algorithm is utilized to determine the preheating time, while Pontryagin's minimum principle (PMP) is employed to solve the multi-objective energy management problem. The efficacy of the proposed method in low-temperature driving scenarios is validated, and the link between preheating needs, cost savings, driving mileage, and changes in the price of energy carriers is also explored. Simulation results indicate that at a -20 C-degrees ambient temperature, grid-and battery-powered preheating solutions could cut energy usage by 48.30% and 44.89%, respectively, to the non-preheating option.