Continuously Variable Transmission Calibration Strategy Based On Virtual Simulation

This paper focuses on the theoretical research and CAE simulation analysis of the speed ratio control strategy of continuously variable transmission.At the same time,TCU calibration is carried out based on the speed ratio control strategy.After the calibration,the whole vehicle power and economy are tested on the real vehicle.Analyze and compare the differences between the theoretical analysis and real vehicle test results,and make relevant corrections to the theoretical analysis,so as to ensure the consistency between the theoretical analysis and real vehicle test,accumulate some experience for the development of similar projects in the future,shorten the development cycle for the subsequent project development and save the project cost.The specific research contents are as follows:Starting from the actual research and development of specific models in a main engine factory,this paper selects the SUV model equipped with a CVT transmission as the research object to study the transmission performance law,control strategy,control method and TCU calibration strategy of CVT.(a)The speed ratio variation characteristics of CVT are studied.According to the driving conditions such as starting,acceleration and deceleration,stable driving and braking,the speed ratio control strategy of CVT transmission is theoretically analyzed,the target speed ratio is determined,and the control method of speed ratio is analyzed.Determine the control logic,and select a more accurate control method through theoretical analysis of the advantages and disadvantages of various control logic.(b)Through the establishment of AVL Cruise simulation model,the simulation model of the vehicle is theoretically analyzed,and the evaluation indexes of power performance and economy are determined.Through the engine data such as external characteristics and universal characteristics measured by engine bench test,the power performance and economy of the vehicle are simulated and analyzed by AVL Cruise software.(c)Because the speed ratio control of CVT transmission has two characteristics:time-varying and nonlinear,based on the above two characteristics,based on the established avlcruise model.Using the scheme of fuzzy PID composite speed ratio controller,combined with Matlab / Simulink software,the AVL Cruise and MATLAB /Simulink joint speed ratio control simulation platform is established for joint simulation analysis.At the same time,a variety of cycle conditions are adopted to verify the rationality and correctness of the joint simulation platform.(d)The real vehicle calibration of CVT is carried out according to the speed ratio curve obtained from the simulation analysis.The main content of TCU calibration is the calibration of the shift curve.A good shift curve can give full play to the performance of the vehicle.The calibration of the shift curve is to verify the matching between the speed ratio and the whole vehicle.(e)Carry out real vehicle test on the power and economy of the vehicle,compare and analyze the test results with the previous simulation,verify the quality of TCU calibration strategy,analyze the differences between them,and modify the simulation model according to the real vehicle test results.(f)Through the discussion,the accuracy of the simulation model can be verified.The above model can be used to calculate the power economy of the whole vehicle for the new project.According to the calculation results,the power economy goal of the new project can be formulated to save the development cycle and project cost for the subsequent project development,At the same time,it can guide the OEMs to carry out TCU calibration development.