Study Of The Control Strategy For Power Battery Thermal Management On Electric Vehicles

The charge and discharge performance of lithium ion power battery is dropped down inlow temperature. In order to solve this problem,this paper takes a square soft packedLiMn2O4battery as the research object. The thermal propertieswere studied, differentheating methods were compared and analyzed in this paper. A simulation study of thebattery pack side heatingis conducted and a variety of variable power heating controlstrategy is proposed.Firstly, thermal impact on battery performance was explored. Through charge/dischargetests under different rates and ambient temperatures, the influence of temperature oncharge/discharge plot, capacity, internal resistance and open circuit voltage, was researched.Secondly, this paper compared pre-heating methods according to the recycle ofdual-source trolley-buses, andevaluated these methods by performance rebounded afterheating, the energy consumption of the heating process, consistency of the temperaturefield, as well as the velocity of temperature rise.Thirdly, basing on heat conduction theory,both mathematical model and finite elementmodel of battery pack pre-heating wereestablished.Material thermal properties, initial andboundary conditions were derived by theoretical calculation and experimental method.Then, the impact of the number of heating film, heating power, the start heatingtemperature and the ambient temperature to the battery pack heating results was simulatedand analyzed.Fourth, two segmented heating variable power control strategy were proposed based onthe pre-heating simulation. The first one issuitable to the vehicle starts at any time and thesecond one is suitable to the vehicle starts at a scheduled time. These two methods not onlyensure the battery pack temperature field uniformity, but also improve the velocity oftemperature rise.