Research On Drive And Shift Control Technology For Electric Vehicle With Two Speed Dual Clutch Transmission

Because of low pollution and noise, energy conservation, simple structure andmaintenance, pure electric vehicles is widespread concerned and has become a hot spot inthe development of automotive industry. Dual clutch automatic transmission (Dual ClutchTransmission, DCT) maintaining the traditional manual transmission simple structure andhigh mechanical efficiency advantages, achieving uninterrupted power shift and improvingvehicle dynamics and economy performace, is a new automatic transmission. Therefore,DCT has become a hot spot in the field of research and development of gearbox.Based on the above background, this paper applies two speed dual clutch transmissionto pure electric vehicle, and research on drive and shift control technology for electricvehicle with two speed dual clutch transmission. the main contents are as follows:(1) Based on the analysis of control system for pure electric vehicle with two speedDCT, drive torque fuzzy control strategy for pure electric vehicle is developed using fuzzycontrol algorithm according to accelerator pedal opening degree, the accelerator openingchange rate and the drive motor speed and two driving modes including power mode andeconomy mode is proposed. The driver model, accelerator pedal fuzzy analytical model,two speed DCT control model, drive motor model, two speed DCT model, battery model,vehicle dynamics model and simulation model of vehicle are established using the Matlab/Simulink software, and simulation tests for pure electric vehicle with two speed DCT underthe ECE, ECE_EUDC cyclie are carried out.The simulation comparative analysis in powermode, economy mode and the normal linear analytic mode are carried out. The results showthat the power and economy performance of pure electric vehicle with two speed DCTbased on drive torque fuzzy control strategy are better than the normal linear analytic mode.(2) Based on the analysis of hill-start assist system of internal combustion enginevehicle, the hill-start control strategy and control flow of pure electric vehicle with twospeed DCT are presented, drive motor target torque of different hill-start process stage iscalculated, the brake pedal and braking force displacement relationship is derived, hill-startof pure electric vehicle is obtained by adjusting motor torque according to braking force.Pure electric car hill-start control model is established using Matlab/Simulink/stateflow,and hill-start simulation results show that the proposed control strategy can assist vehicle complete hill-start with no slip, small jerk, and good starting results.(3) Methods for determining the clutch target torque during shift process of DCT areresearched based on the analysis of different stages of the shift, and dynamic model of eachshift phase is established. According shift quality evaluation indicators, two objectivefunctions is determined using jerk and friction work, the shift process optimizationconstraints are established, clutch target torque is optimized during shift using paretomulti-objective genetic algorithm, different sets of clutch target torque trajectory areobtained, and the simulation of shfit is carried out. The simulation resluts show that usingpareto multi-objective genetic algorithm for the target torque trajectory optimization ofclutch during shift can obtain different sets of clutch target torque trajectory, recieve a bettershift quality, and supply more selectable programs for clutch target torque control duringshift.(4) Dry clutch torque model is established based on the analysis of dry dual clutchstructure, lever spring load characteristics and proportional flow valve characteristics areanalyzed. Because the traditional control methods has problems in nonlinear control, thegeneralized regression neural network is applied to the clutch shift control. GRNNintelligent control method for the displacement of clutch is proposed, and simulation modelis established. The simulation results show that the displacement is controlled with highprecision and small error by using clutch displacement GRNN control algorithm which canmeet the control accuracy requirements of dry dual clutch shift.(5) Electronic control system of electric vehicle with two speed dual clutchtransmission is designed, hardware and software for pure electric vehicle electronic controlsystem are developed, and vehicle test is carried out to verify the proposed control strategy.Through theoretical analysis and experimental study, drive and shift control technologyfor electric vehicle with two speed dual clutch transmission are researched. The test resultsshow that dynamics and economy, hill-start performance, shift quality of vehicle areimproved, and this paper has a certain reference value for pure electric vehicle drive andshift technology research.