| The increasing severity of energy crisis, environmental pollution and greenhouse effecthas put forward higher requirements for energy-saving and emission reduction to theautomobile industry. In addition to further technological innovation to improve theenergy-saving effect of traditional automotive, the development of new energy vehicles hasbecome an inevitable trend of automobile industry reform. Pure Electric Vehicle (PEV) hasbeen widespread concern in the whole world because of its great potential for energy-savingand environmental protection, and easier industrialization. Governments and autocompanies have taken the industrialization of PEV as the recent development goal, whichsimultaneously puts forward more urgent and actual requirements to improve thetechnology level as well as the vehicle performance of PEV.The improvement of technology and performance of pure electric vehicle requires thecollaboration of OEMs and component suppliers, and they should fully play their respectivetechnical and industrial advantages. The component suppliers should further enhance theircomponents· level of technology R&D, production and manufacturing. And the OEMsshould establish a key technology R&D system of PEV relying on the existing product andtechnology platform, complete the integration of vehicle and powertrain components,develop and perfect vehicle control technology to play the full role of vehicle performanceincluding power performance, economy performance, and cost behavior, so to expand themarket and user acceptance of PEV and promote the industrialization.Relying on the requirements of the863Program The Design and Technical Development of FAW New Structure Small Pure Electric Vehicleμ (No.2011AA11A219),the International Science and Technology Cooperation Project Collaborative Research onPowertrain Technology Platform of New Structure Small Pure Electric Vehicleμ (No.2012DFA61010), and the Technology Development Plan of Jilin Province Research onKey Technology of Vehicle Control System for New Structure Small Electric Vehicleμ (No.20116002), and relying on the close cooperation with China FAW Group Corporation R&DCenter, this paper carries out the research on powertrain technology platform, powertrainparameters design and optimization, and FAW next generation PEV control technology. Themain contents of this paper are as follows.1. The vehicle performance requirements and their main influencing factors areresearched based on the analysis of the movement mechanical characteristics.(1). Analyze the vehicle performance requirements and the corresponding evaluationindexes from the three aspects of power, economy and cost characteristics. The cost ishighlighted as one of the key indicators of performance evaluation, and the driving rangewithin battery life cycle is taken as an important indicator of maintenance and operationcost of PEV.(2). The importance of reducing automotive weight to improve vehicle economy levelsis cleared by the energy consumption sensitivity analysis. And the weighted average ofmultiple driving cycles is taken as the basis of economy evaluation. Then analyze theadvantages of using two speed transmission in PEV, and take two speed as the basicprinciple of transmission selection.Put forward the feasible direction and target for the vehicle performance optimization bythe analysis of the performance requirements and the corresponding influencing factors.2. Systematically research the characteristics and laws of the two major powertraincomponents (electric motors and power batteries) used in PEV by combining mechanismanalysis and experimental research. (1). Based on the working principle of Permanent Magnet Synchronous Motor used invehicle, research the internal relations between the feature parameters and componentcharacteristics of motor system and the vehicle performance, including the impact of batteryvoltage to the motor output power, the impact of motor base speed to the accelerating powerdemand of vehicle, the impact of peak torque to the quality of the motor system, and theequivalent estimation of motor efficiency and distribution range using key feasureparameters, and etc.(2). By the experimental research to the samples of the target battery, clear the maininfluencing factors of power battery characteristics which are closely related to the vehicleperformance, and research the characteristic laws of the open circuit voltage, the capacitycharacteristics, the rate discharge characteristics, the internal resistance characteristics, theenergy efficiency characteristics and the cycle life characteristics.Through the characteristics research of the powertrain components, establish the tie andbridge between PEV and powertrain components, conductive to put forward more practicaltechnology demands to the powertrain components from the point of vehicle, and providemore accurate data support and technology foundations for powertrain system modeling andperformance optimization.3. Research the powertrain parameters design technology of PEV, take the improvementof vehicle performance potential as the design target, complete the powertrain parametersdesign and optimization for the target vehicle, and carry out the simulation analysis.(1). Take the vehicle curb weight as the key representational factor of economy and costcharacteristics and put forward the minimum of vehicle curb weightμ manual parameterstuning program which takes the power performance indexes as the entry point and takes thesingle driving range and full life-cycle driving range as the restriction and adjustmentfactors, and realizes weight reduction target by manual tuning of powertrain parameters.This program doesn·t have to create complex system models and only needs less workload to realize the key feature parameters design to meet the requirement of economyperformance and cost characteristics of PEV.(2). Because of the influences of the overall efficiency of powertrain systems in the realdriving cycle on vehicle performance are not fully considered in the manual parameterstuning program, a global optimization method· for powertrain parameters is proposed,which takes the economic indicators and vehicle curb weight as the comprehensiveoptimization goals, and power performance as constraint, to realize the global optimizationof the powertrain parameters by establishing the optimization mechanism that combinedoptimization software and electric vehicle performance simulation software, maximizes thepotential to enhance the vehicle performance from powertrain parameters design.(3). Simulation comparison was carried out in the vehicle performance simulationplatform with the vehicle parameters before and after optimization, the results showed thatthe curb weight minimum manual parameter tuning optimization scheme could effectivelyachieve the basic requirements of the vehicle weight reduction, and on this basis the globaloptimization method could further reduce vehicle energy consumption level, and enhancethe economy potential.The optimization to the powertrain parameters of target vehicle can realize the expecteddesign goals and requirements that reduce the vehicle curb weight and improve theeconomy performance on the premise of ensuring the power performance.4. According to the structural characteristics of PEV and the development goal of thevehicle control system products, determine the vehicle control system software frameworkconsists of Power Mode, Economic Mode and Limp-home Mode, and develop a torquecontrol scheme of Ref-Torque MAP plus Fuzzy Torque Compensation based on the PowerMode and Eco Mode.(1). In Power Mode, take highlighting the vehicle power performance as the goal. Byincreasing the accelerator pedal load coefficient in the Ref-Torque MAP, increasing the torque compensation, and introducing hard acceleration intension recognition and torquecontrol strategy with higher sensitivity to effectively improve the vehicle’s powerperformance.(2). In the Eco Mode, appropriately reduce the amplitude of Ref-Torque MAP in orderto reduce the demand on the output power and discharge rate of the power battery whenunder the same accelerate pedal position, to improve the energy efficiency, and to extend thedriving range. At the same time, for the different accelerate demand of the driver, provideappropriate compensation torque to the Ref-Torque MAP, to consider the basic drivability,and enhance the driving experience and the practicality of the Eco Mode.(3). Develop the torque constraint control strategy in allusion to the abnormalphenomena which have not evolved to the stoppage fault such as motor over-temperatureand power battery under-voltage, to make the PEV have limp home function on the premiseof avoiding irreversible damage to the powertrain components, and improve the PEV·scapacity of processing the abnormal phenomena.Develop the vehicle control strategy to rich the control functions, enhance the controleffect, and meet the objectives and requirements of vehicle control system.5. Taking dSPACE as the rapid control prototype, code transformation and parameterstesting were carried out to the target vehicle·s control strategy, and then the real vehicletorque control and performance testing experiments were completed on the roler bench,focusing on verification of control functions·realization and actual control effect under eachcontrol mode. The test results demonstrated the realization of each control function, andshowed the effectiveness of the control strategy developed. |
PDF Full Text Request