Research On Energy Management Strategy Of Extended Range Fuel Cell Electric Vehicle Considering Energy Source Temperature

The game between the energy crisis,environmental issues and social development has promoted the transformation of traditional fuel vehicles to new energy vehicles.The extended-range fuel cell electric vehicle has become one of the main development directions in the future automobile due to its high efficiency,pollution-free and long cruising range.However,the current fuel cell has short life and high operating cost,which makes it difficult to promote fuel cell vehicles on a large scale.Energy management strategy design is one of the key technologies to improve vehicle economy and extend the life of energy sources.Temperature has a greater impact on the output characteristics of the energy source,and high temperature is one of the important factors affecting the life of the energy source.Therefore,this paper designs an energy management strategy under thermal constraints to protect the energy sources;in addition,in view of the high heat generation characteristics of fuel cell,when the ambient temperature is low,an energy management strategy based on the utilization of stack waste heat is designed to improve vehicle economy.The main contents are as follows:(1)Based on a semi-empirical formula,a fuel cell voltage model considering the influence of temperature is established,the temperature characteristics of the fuel cell are analyzed,and a fuel cell temperature rise model is established according to the heat balance equation;the power battery is modeled based on the internal resistance model,and the temperature rise model of the power battery is established.(2)Through the analysis of the current mainstream control strategies,a hierarchical energy management strategy based on the SOC state is designed,and the strategies with or without thermal constraints are compared to illustrate the necessity of thermal constraints.And based on the genetic algorithm,the threshold value based on the SOC state strategy under the thermal constraint is optimized,which improves the economy of the whole vehicle.(3)Based on Pontryagin’s Minimum Principle(PMP),a global optimization strategy under thermal constraints is designed,and a shooting method is used to solve the initial value of the co-state,which significantly improves the economy of the vehicle.(4)For the problem that the global optimization strategy cannot be applied online and in real time,a vehicle speed predictor is built based on the generalized regression neural network,the SOC trajectory is planned based on the expected mileage,and the Model Predictive Control(MPC)under thermal constraints is designed.The hierarchical energy management strategy realizes the online control of the energy management strategy and reduces the energy consumption of the whole vehicle.(5)In response to the problem of poor economy of electric vehicles in low temperature environments,the waste heat of the stack is used to heat the passenger compartment.The energy consumption of air-conditioning accessories and fuel cell warm-up efficiency under low temperature environment are analyzed.Considering the fuel cell warm-up process and using the waste heat of the stack,a dual-state control strategy based on PMP is proposed to reduce the energy consumption of the whole vehicle.