Energy Management Control Strategy And Control Parameters Optimization Of 48V Hybrid Electric Vehicle

With the increasingly serious problems of environmental pollution and energy shortage,the automobile emission regulations of various countries are becoming increasingly stringent.As a transitional product between traditional fuel vehicle and blade electric vehicle,hybrid electric vehicle has both different advantages,and has great potential in reducing fuel consumption and emission.The 48 V HEV system increased 48 V battery and motor based on the traditional 12 V automobile electrical system,it was low cost,simple structure and easy matching in comparison with high voltage HEV system,and more energy-saving compared with a 12 V Start-Stop system,it has has a bright prospect before the overall popularity of HEV and BEV.Vehicle Control Unit is the core unit to coordinate all parts of vehicle power system,and its control strategy has great influence on vehicle power and fuel economy.Therefore,the 48 V hybrid electric vehicle integrated with ISG(Integrated Starter Generator,)as the research object,designs and optimizes the vehicle energy management and control strategy.Firstly,the configuration schemes of 48 V hybrid electric vehicle with different layouts are introduced.The feasibility,function and advantages and disadvantages of each configuration scheme are analyzed.Considering a greatly degree reduction of fuel consumption,a 48 V HEV system scheme with ISG integration is selected and studied,taking a traditional car as a reference prototype to select and match each components.Secondly,the operation mode and power flow of the vehicle are expounded and analyzed in detail.In order to improve the fuel economy,a vehicle energy management control strategy based on logic threshold is formulated.To establish a vehicle simulation model,and set up the vehicle control strategy model and vehicle model joint simulation,the simulation results show that the control strategy can get reasonable torque distribution and better speed tracking effect,and obtained the equivalent value of vehicle fuel consumption and emissions,the equivalent fuel consumption per hundred kilometers compared to the prototype car reduced 12.3%.Finally,the multi-objective optimization method is used to optimize the vehicle economy and emission performance comprehensively.The electricity consumption of the whole cycle is converted to fuel consumption,then the equivalent fuel consumption is calculated.Taking the equivalent fuel consumption and emissions as the optimization objective,the NSGA-? algorithm is applied to optimize the 5 main control parameters of the main transmission ratio and the battery in the control strategy.The results show that under the NEDC cycle,the equivalent 100 km fuel consumption is reduced by 6.5% compared with that before the optimization,and the CO,HC and NO_x in the emission are reduced by 11%,9.3% and 10% respectively.It is proved that the multi-objective optimization design of this paper has obvious improvement effect on the fuel economy and emission of 48 V Hybrid Electric Vehicle.