Research On Coordination Control Technology Of Shifting Process In Pure Electric Vehicle Electric Drive System

With more and more countries proposing timetables for stoping selling of fuel vehicles,China has also issued“dual-slope”policy.As electric vehicles are the most promising new energy vehicle,it is worth researching.The integration and control of the motor and gearbox has gradually become a hot research topic due to low cost with better performance.In this paper,it takes an electric logistics vehicle equipped with a permanent magnet synchronous motor and a non-synchronizer two-speed automatic transmission as the the research object.On the basis of completing the dynamic matching,the quantitative analysis of shifting process was carried out;the strategy of coordinated control of the drive motor,gearbox and shifting actuator was established.According to the shifting quality criterias of evaluation,the algorithm,NSGA-2(Non-dominated Sorted Genetic Algorithm-?),was used to optimize the shifting process based on different driver styles.The full text mainly includes the following contents:(1)With statistics of typical urban working conditions data,high-frequency working points in the overall operation are obtained,and the matching work of motor,gearbox and vehicle was finished.The contents mainly include:rated power,rated torque,maximum power,and maximum torque of motor,gear ratios of the gearbox,and ratio of main reduction gear.(2)Establish a dynamics model of vehicle,which includes:a driver model for torque decision combined by model-based feedforward control and close loop feedback control on velocity;the model of motor,gearbox and main reduction;a control model for studying the dynamic adjustment characteristics of the drive motor.In terms of the control of motor,several control strategies below the base speed of permanent magnet synchronous motor were analyzed,and the strategies that MTPA(Maximum Torque Per Ampere)and i_d=0 were compared for the performance in software implementation.For the control of the weak field of the drive motor,an improved negative i_d compensation method was proposed,which expands the constant torque working area and completes the smoothly control of transition from the constant torque zone to the Field-Weakening region of the drive motor.(3)Establish a model used for driver short-term driving style's recognition.It includes:analyzing driving data and driving styles of different people in different situations,studying the possible pedal operation characteristics under different driving styles;formulated fuzzy rules considering the possible feature of pedal characteristics and establish a fuzzy controller used to identify the driver's short-term driving style.the control parameters of the shifting process will be determined and the driver model will be completed with the driving style.(4)The evaluation index of the shifting quality of the AMT(Automatic Machincal Transmission)for electric logistics vehicle without clutch and synchronizer was proposed.According to this,the range of shifting control parameters was quantitatively studied,and the multi-objective optimization of control parameters in the whole shifting process based on NSGA-2 was completed.Firstly,the characteristics of each shifting stage and the motion of each related component were analyzed,and the dynamics models of the components in each stage were established.Secondly,the mathematical quantification relationship between shifting control parameters and shifting jerk,total shifting time was analyzed;then,ADAMS was used to establish a virtual prototype to simulate the shifting jerk and shifting time under different shifting parameters,further more,it can determine the control parameters;after then,according to the dynamic model and shifting quality evaluation indicators,it takesd the shifting jerk and shifting time as the indexs to establish objective functions to realize multi-objective optimization of the motor torque unloading speed,motor residual torque,speed difference of synchronous meshing,moving speed of meshing sleeve and motor torque recovery speed in the whole process of shifting.And with the method of NSGA-2 we can get the Pareto optimal solution.Finally,the determination of the individualized shifting control parameters under different style factors was performed based on the short-term driving style intensity factor.(5)Improve and verify the performance of shifting control strategy.First,the bench test was carried out to verify the response performance of the motor control;then,the actual vehicle test was carried out to verify the effect of the personalized shifting process and the coordinated control of the active parts by judging the shifting time,the shifing schedule,the relationship between the shifting jerk and the driving style.The test includes:regulation ability and accuracy test of motor speed with bench,shifting performance test of bench,and shifting test in vehicle under different pedal operations or different driver style.