Research On Predictive Energy Management Strategy Of Hybrid Vehicle

With increasing concern over environmental pollution and energy crisis,countries worldwide have higher requirements for environmental protection and efficient use of energy.Hybrid vehicle is a promising solution for long-distance and heavy-duty transportation with heavy trucks due to low fuel consumption,low emissions,strong power,and long range.In order to improve the energy-saving rate of heavy trucks under high-speed cruising conditions,considering the influence of road changes on vehicle fuel consumption based on ADAS map,this paper conducts research on predictive energy management strategy(PEMS)of hybrid heavy trucks.The aim is to carry out predictive planning and control of vehicle speed and energy distribution of power components with the road information.Under the premise of ensuring the transportation timeliness,the fuel economy of hybrid heavy trucks can be improved efficiently.The specific research contents are as follows.Firstly,the hybrid heavy truck simulation model and road model are established.Based on the vehicle parameters and dynamics,the component models and vehicle model are built to realize the accurate calculation and simulation of each component.According to the highway design criteria,the typical road slope model is established,which includes four typical working conditions of uphill,downhill,up-downhill and down-uphill.Additionally,real highway road data is processed using the wavelet filtering algorithm to complete the construction of the real road model.Secondly,the energy saving principle and design objects of PEMS are analyzed,where the overall scheme is determined according to the design objects,and the PEMS hierarchical control strategy is proposed based on the dynamic programming algorithm.The upper-level algorithm performs vehicle speed planning,and the future speed sequence that minimizes the energy consumption of power components is determined based on the change of road slope;the lower-level algorithm performs energy distribution,the required driving power of whole vehicle is calculated based on the speed planning results of the upper-level algorithm,and the energy distribution of power components is determined with the goal of minimizing engine fuel consumption.In the design of vehicle speed planning algorithm,the influence of different penalty coefficients in the cost function on the planning results is analyzed,and the final penalty coefficients are determined from two aspects of speed following and fuel economy.Thirdly,this paper investigates the single-layer control strategy of PEMS using the model predictive control(MPC)algorithm.Based on the change of road slope ahead,the single-layer control strategy simultaneously optimizes the future vehicle speed and energy distribution with the objective of minimizing engine fuel consumption.In order to reduce the computational complexity of the algorithm,the traditional optimization algorithm can be replaced by the dimension reduction iterative algorithm,which is optimized from the aspects of calculation process and search range limitation.The algorithm convergence,result optimality and computation speed are verified based on the real road condition data,and the results show that dimension reduction iterative algorithm can reduce the quantity of computation while ensuring the optimization effect,and can be applied to the optimal solution of PEMS single-layer control strategy.Finally,the simulation model is validated based on the real vehicle test data to ensure the credibility of the model calculation.The energy-saving effects of hierarchical control strategy and single-layer control strategy of PEMS are verified based on the typical road slope model,and the final results are compared with the results of dynamic programming energy management strategy under cruise control system.The real vehicle test data of the target vehicle equipped with rule-based energy management strategy under driver-controlled speed conditions are selected,and the results are compared with the simulation results of PEMS hierarchical control strategy and singlelayer control strategy on the same road section.In light of the experimental results and algorithm design objects,it can be concluded that the predictive energy management strategy,which considers the influence of vehicle speed and energy distribution on vehicle fuel saving,is effective in improving the fuel saving rate of hybrid heavy trucks during high-speed cruising conditions.