| China is a country with a large number of cars and is increasing year by year.Although the share of commercial vehicles accounts for only 13%of its total,the commercial vehicle industry has become the main battlefield of "carbon emission reduction" because the emission of heavy commercial vehicles is about equivalent to that of 300 passenger vehicles.At the same time,with the proposal of the national "double carbon" goal and the gradual increase of the market demand for new energy heavy commercial vehicles,energy conservation and emission reduction and "double carbon" goals seem to point out the direction for the research and development of commercial vehicles.The new energy of commercial vehicles is the general trend.At present,the integrated electric drive assembly of new energy commercial vehicles has gradually become one of the mainstream R&D products in recent years.Aiming at the problem of power interruption in shift of integrated electric drive assembly transmission,a new non power interruption shift logic of dual motor drive assembly is proposed,and the shift quality of the EV truck is improved.Taking the pure electric heavy truck as the research object,this thesis comprehensively studies the vehicle performance of single motor drive assembly and the technical defects of gear shift power interruption;Aiming at its technical defects,the dual motor integrated drive assembly is developed,the power uninterrupted shift logic is proposed,the problem of power interruption is improved,and the improvement of its power and economy is compared and studied.First,combined with the current severe situation of commercial vehicle emission in China,this thesis analyzes the background and significance of the research on the transmission of new energy commercial vehicles.Although the structural types of electric drive assembly of new energy commercial vehicles are diverse,integrated electric drive assembly is still one of the mainstream technical solutions.In the research of gearshift of integrated electric drive assembly,the important problem to be faced is the power interruption problem.Researching,analyzing and solving the problem of power interruption has become a key factor restricting the development of integrated electric drive assembly.Second,the configuration design of the dual motor drive assembly is completed.Firstly,this paper studies the type of the shift mechanism of the commercial vehicle electric drive assembly,and determines that the dual electric drive assembly adopts the electro pneumatic shift mode.Then it studies the general layout requirements of commercial vehicles for electric drive assembly and the performance requirements of new energy commercial vehicles for electric drive.In order to improve the quality and competitiveness of the whole vehicle,it also has higher requirements for NVH(Noise,Vibration,Harshness),lightweight and other attributes of electric drive assembly.Finally,the configuration of the dual motor drive assembly is completed.The dual motor is used to match the independent deceleration and shift mechanism.A reasonable mechanical configuration scheme is provided to improve the power interruption of gear shifting.Third,based on the basic parameters and performance objectives of the vehicle,this paper completes the parameter matching and design of the dual motor drive assembly.The first step is to sort out the design input parameters of the electric drive assembly and the vehicle performance objectives,such as power indicators and economic indicators.The second step is to complete the matching and selection of the motor parameters of the dual motor drive assembly.The peak power of the dual motor is 560kW and the rated output torque is 1360 nm.At the same time,the transmission ratio of the EMT(Electronic Mechanical Transmission)transmission of the electric drive assembly is calculated and determined:11.218 for the first gear and 4.569 for the second gear,which provides parameter support for the subsequent study of the shift curve law of the dual motor drive assembly.Four,this paper completes the shift logic and shift curve calculation of dual motor drive EMT.The first step is to study the type and characteristics of the shift curve of the electric drive assembly.The second step is to study the evaluation indexes that affect the shift performance of commercial vehicles,and output the subjective evaluation method of the shift performance of commercial vehicles.The third step is to complete the shift logic design of dual motor driven EMT according to the vehicle parameters.The control logic of dual motor step-by-step shift can ensure that at least one motor can continuously output power during the shift process.Finally,according to the vehicle parameters,the shift curves under different working conditions are calculated,including economic,power and combined shift curves.Five,the third step is to complete the shift logic design of dual motor driven EMT according to the vehicle parameters.The control logic of dual motor step-by-step shift can ensure that at least one motor can continuously output power during the shift process.Finally,according to the vehicle parameters,the shift curves under different working conditions are calculated,including economic,power and combined shift curves.Finally,the process of building the simulation model of the electric drive vehicle is introduced,and the power and economy of the electric drive assembly are simulated.Through comparative analysis,part of the dynamic performance indicators of the dual motor drive assembly scheme have been significantly improved,in which the 0-80km/h shift acceleration time has been increased by 12.5%,and the 1%and 4%slope continuous speed has been increased by 19.66 and 63.04%.By studying the power interruption of single motor and dual motor drive assembly,it is found that the dual motor drive assembly can effectively maintain power output during gear shifting,with an acceleration of 0.479m/s2,which is close to the vehicle acceleration before and after gear shifting(0.561m/s2,0.551m/s2).It is found that the shift impact of the dual motor drive assembly is similar to that of the single motor drive assembly.Finally,the powertrain test is carried out on the bench,and the road test of the whole vehicle is carried out to verify the accuracy of the simulation results.Through vehicle simulation and real vehicle verification,it can be concluded that the vehicle speed is increased by 4.057km/h during the step-by-step shift of dual motors,and this shift strategy can improve the power interruption problem. |
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