| In recent years,with the shortage of petroleum resources and the pressure of environmental protection,countries around the world regard electric vehicles as the development direction of the automobile industry.In July 2015,the National Development and Reform Commission and the Ministry of Industry and Information Technology issued the "Regulations on Investment Projects and Production Access Management for Newly Built Pure Electric Passenger Vehicle Manufacturers",which puts more stringent reqiurements for the acceleration performance,driving range and energy consumption rate of the vehicle.Based on the current domestic and international technology status and market demand,this paper proposes the use of AC asynchronous motor as the power drive mode to develop a new two-speed automatic mechanical transmission(AMT)drive and control system design ideas,with small electric vehicles as the research object This paper focuses on the AC asynchronous motor+two-speed automatic shifting drive scheme,through the solid design of the two-speed transmission,the design and simulation of the electric shift actuator,the software and hardware development of the electric drive two-speed transmission control system,and designment of the overall drive system.The main research content includes:Firstly,according to the modular development idea,according to the overall structure of the new drive scheme of AC asynchronous motor and two-speed automatic shifting drive scheme,the matching design of the drive motor module,power battery module and two-speed AMT transmission module is carried out.In the design of two-speed AMT transmission module,the matching of speed ratio of two-speed AMT system is studied according to the driving requirements of vehicle under starting and accelerating conditions,and the transmission ratio of two-speed AMT system and main reducer are determined respectively.Secondly,based on the modular matching design,the main mechanism of the two-speed AMT transmission system,the electric shifting mechanism,is studied.In the development of electric shifting actuator,the electric shifting mechanism of brushless DC motor+worm gear reduction mechanism+ cam drum+synchronizer is proposed,and the design and modeling of two-speed AMT shifting mechanism worm gear and rotor cam are proposed.And the synchronizer is calculated and modeled to complete the overall design of driving system.Thirdly,dynamic simulation of two-speed AMT transmission is carried out by using ADAMS simulation software.Firstly,the synchronizer is simulated and analyzed,the synchronizer combination process is defined in ADAMS,and the main working components are motion constrained to verify the reliability of the established synchronizer model.Then,the whole two-speed AMT transmission is analyzed by combining the electric shift mechanism with the synchronizer model and the transmission system.and to study the force and displacement relationship between the shifting motor and the synchronizer during the upshift and downshift.At the same time,the software and hardware of dual-speed transmission control system are developed.The main circuit of transmission control unit(TCU),input and output conditioning circuit and communication circuit are designed by using freescale MC9S12XS128 control chip.The control software system of TCU for two-speed transmission is developed,which includes main program,input signal acquisition program,two-speed AMT shift control program and CAN communication program.The communication protocol of TCU and MCU cooperative control is defined to realize TCU and MCU cooperative control.Finally,a two-gear AMT system test bench is built,and the control performance of TCU is validated through load-free,different speed shift test and automatic shift test under cyclic conditions.To compare the test data and simulation data,and the bench test results show that the two-speed AMT transmission assembly and control system designed in this paper are reasonable and can meet the requirements of automatic shift of the whole vehicle. |
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