Research On Energy Management And Mode Switching Strategy Of Dual Motor Multi-gear Coupling Powertrain

New energy vehicles are the first choice to solve the problem of fuel vehicle emissions and oil consumption.Therefore,the government's strong support has also given birth to the vigorous development of the new energy automobile industry.Although China's auto industry suffered the first negative growth after 28 years of rapid growth in 2018,the sales of new energy vehicles continued to grow against the trend.Pure electric vehicles are the best development direction of new energy vehicles.Their development has been limited by the bottleneck of cruising range.Under the condition of limited battery energy density,it is an effective way to optimize the vehicle drive configuration and reduce drive loss.Therefore,this paper combines the economic advantages of dual motors and the power advantages of multi-speed drives to study the energy management and mode switching strategies of Dual-motor Multi-gear Coupling Powertrain(DMCP)to enhance pure electric.The main research contents of the thesis are as follows:By comparing and analyzing the advantages and disadvantages of multi-speed ratio and fixed speed ratio,dual motor and single motor structure,a new DMCP configuration is proposed.This configuration uses two motors,three gears,for mode switching via clutch and synchronizer.Then introduce the principle of five driving modes of DMCP,and carry out the power system transformation for a single motor fixed speed ratio pure electric vehicle to match the relevant parameters of DMCP.Finally,build the DMCP model based on AMESim soft ware to verify the dynamic performance of DMCP under the primary selection parameters.According to the research on the energy saving potential of DMCP,the genetic algorithm is used to optimize the gear parameters of DMCP.For the characteristic analysis and power calculation of the five driving modes of DMCP,the lowest power driving mode distribution map of 0-120km/h is drawn by MATLAB programming.The boundary of the model is adjusted and the driving mode is simplified by data analysis.For the problem of dual motor power distribution in coupled mode,this paper designs a fast and computationally close and optimal power allocation algorithm.In order to study the multi-mode switching of DMCP,combined with the characteristics of torque compensation of dual motors,10 mode switching strategies without power interruption are designed.Based on the existing AMESim model,the detailed driving motor model is established,including the corresponding torque control algorithm.For the problem of multiple changes of motor torque during mode switching,the torque control algorithm of the drive motor is designed to achieve stable torque variation.The forward simulation and co-simulation methods are used to verify the energy management and mode switching strategy of DMCP.The simulation results show that the gears and torque distribution of DMCP under NEDC,UDDS and JC08 conditions can achieve the expected effect,and drive in the lowest power mode,which is 8%~12%economical compared to single motor system.The simulation analysis of three modes is adopted.The results show that DMCP can achieve no power interruption compared with single motor system,and the impact degree is less than 0.6 m/s~3.