Research On Adaptive ECMS Based Energy Management Strategy Of Range-Extended Electric Vehicles

In order to cope with global warming,energy crisis and enviro N.mental pollution,the automobile industry began to accelerate the development of energy-saving and new energy vehicles.As an important branch of new energy vehicles,range-extended electric vehicles(REEVs)have attracted extensive attention in the industry due to their advantages of high full-time electric drive efficiency,no range and charging anxiety.The REEV has two energy sources: power battery and range extender.The energy management strategy of power distribution between different energy sources directly affects the performance of the vehicle.In this paper,energy management strategy based on instantaneous optimization and adaptive equivalent fuel consumption minimization is studied for REEV powertrain.First of all,based on the MATLAB/simulink,the vehicle forward simulation platform was built for a range extended electric vehicle,in which the controlled objects include engine model,generator/drive motor model,power battery model and vehicle driving dynamics model.The controlled object model was verified by real vehicle road test data,and the results show that the model has good accuracy.In order to truly consider the dynamic response process of the power generation of the range extender,a dynamic control model of the range extender controller was built in the simulation platform.The simulation and bench test results show that the range extender controller model can respond to the target power generation quickly and accurately,which truly reflect the dynamic change process of the power generation of the range extender.The paper studied and presented the Pontryagin’s minimum principle(PMP)method to solve the problem of REEV energy management.The range extended energy management strategy was designed by using equivalent fuel consumption minimization strategy(ECMS),which is similar to PMP principle.The relationship between the key parameter of the strategy-the equivalent factor and the costate quantity of PMP,charge and discharge state was analyzed.Combined with the vehicle forward simulation platform,the strategy function was verified under the fixed equivalent factor.The larger the equivalent factor is,the energy management tends to use fuel oil,and the opposite is to use electricity.In view of the difficulty in determining the equivalent factor in different working conditions,an adaptive equivalent factor algorithm based on SOC feedback PI regulation was designed in this paper,and then an adaptive ECMS(AECMS)of range extended energy management strategy is constructed.Compared with the simulation of ruled energy management strategies such as thermostat strategy and power following strategy,the A-ECMS strategy performs better in fuel economy and battery loss under different operating conditions and different initial SOC conditions.Taking the initial SOC of 30% and WLTC condition as an example,the final SOC of A-ECMS strategy is 30.295%,and the comprehensive fuel consumption of 100 km is 6.78 L,which saves 6.2% and 3.4% compared with thermostat strategy and power following strategy.Meanwhile,the effective ampere-hour flux of the battery is 10.78 Ah,which is the lowest among the three,and is more beneficial to improving battery life.