Research On Energy Management Strategy Of Coaxial Parallel Hybrid Electric Vehicle

In recent years,with the rapid increase in the number of environmental pollution and energy shortage are becoming more and more serious.Energy conservation,emission reduction and low-carbon travel have become the focus of attention all over the world.Many scholars have carried out a serious of related research and application.The ultra-long range and low emission capacity of hybrid electric vehicles can solve the problems of short mileage of pure electric vehicles and exhaust emissions of fuel vehicles.Through the establishment of adaptive energy management strategy,the control of the whole vehicle in all aspects can reach the best state.Therefore,how to distribute the energy reasonably and adjust it to the optimal is very important.Taking a small passenger vehicle as the research object,this paper studies the energy management strategy of coaxial parallel hybrid electric vehicle.First of all,based on the comprehensive analysis of the three structural types of hybrid electric vehicles and their respective advantages and disadvantages,it is determined that the coaxial parallel P2 hybrid electric vehicle is taken as the main research object,according to the basic parameters of a certain type of vehicle,select the appropriate engine,motor,transmission,battery and other key components.Then,in other to verify the road conditions and approach the actual performance of the vehicle,the maximum speed,100 km acceleration time and climbing performance of hybrid electric vehicle are established,and the parameters of engine,battery and motor power are matched according to the complexity of WLTC operating conditions.Secondly,the working principle of parallel hybrid electric vehicle is briefly analyzed,and the energy management strategy based on determining rules is designed.After establishing a serious of logical relations,key parameter variables and parameter thresholds,five working modes are established with the help of software MATLAB/Simulink and experience,which are one pure electric mode,three hybrid modes and one energy recovery mode.The goal is to minimize the fuel economy and power consumption performance of the hybrid electric vehicle,strictly stipulate the access conditions and torque distribution rules under different working modes,complete the construction based on the regular energy management strategy,and analyze the simulation results.Then,on the basis of determining the regular energy management strategy,adding PI and fuzzy braking control as the optimal control strategy,a method of combining vehicle target output torque with PI dynamic control is proposed to reduce the difference between target output torque with PI dynamic control is proposed,which provides a reasonable regenerative braking system,so as to improve the efficiency of energy recovery.Finally,the vehicle model is built by CRUISE simulation software and the electrical and mechanical signals are connected,and then joint simulation is carried out with MATLAB software.Firstly,the power and climbing performance are simulated and analyzed,and three cycle conditions of NEDC,WLTC and CLTC-P are established.The simulation results of energy management strategy before and after optimization are analyzed,in which the speed error,mode switching,battery SOC,fuel economy and exhaust emissions are simulated and compared.It is proved that the vehicle performance index of the optimized energy management strategy meets the requirements,the speed error is significantly reduced,the fuel economy and pollutant emissions are reduced,and the power consumption is also reduced to achieve comprehensive optimization.