| The new powertrain driving system integrated with drive motor and transmission of pure electric vehicle has the characteristics of compact structure,high power density and wide speed range.As an important part of the power transmission system,it optimizes the power output of the system by adjusting the speed of driving motor and the shift point of the transmission to meet the acceleration,deceleration,climbing,braking and other driving conditions of pure electric vehicles.Its performance parameters and control accuracy have a vital impact on the power,economy and comfort of the whole vehicle.In the development process of key components,the establishment of test-bed plays an important role in accurate measurement and control of powertrain drive system,and shortens the development cycle of powertrain system and reduces the risk of development and testing.Referring to the traditional evaluation method of power system,this thesis presents an evaluation method for the driving performance of a new type of power assembly drive system which integrates drive motor and transmission.In the design and analysis of the evaluation method,the analytic hierarchy process(AHP)is used to select seven evaluation indexes which have great influence on the power drive system: temperature rise of peak power,maximum working efficiency under rated power,transmission ratio density,high efficiency interval efficiency,precision of torque control,maximum working speed and peak torque.The corresponding weights of each index are determined,and the evaluation formula for this type of assembly is established to evaluate its performance score.Based on the test technology and method,and according to the requirement of the evaluation system index,this thesis makes a detailed study on the requirement analysis and overall planning of the measurement and control system of the new driving assembly testbed.The structure of the mechanical system and the electrical-control system of the test-bed are elaborated in detail.The hardware structure and connection of the test-bed are designed,and the main control modes of the measurement and control system are analyzed.The hardware structure and connection of the test-bed are designed,and the main control modes of the measurement and control system are analyzed.The electric measurement and control system is divided into real-time control,field communication and data acquisition.The acquisition methods of speed,torque,voltage and current are determined.The specific models and technical parameters are defined according to the function requirements of the main hardware components.This thesis takes LABVIEW and PLC as the core of program design,and designs the host computer and slave computer control programs of the measurement and control system.Using OPC technology,the communication between upper computer and lower computer is realized,and the communication and precise control functions of frequency converter and dynamometer are realized by programming in software.Based on LABVIEW the main design process of the software is analyzed,the main interface of the operation is drawn,and the modular design of the main functions of the host computer program is completed by using parallel thread execution loop technology.Through the design of the above software program,the application of related technology is realized.According to the composition of power assembly drive system and the test requirements of the indicators,this thesis designs the test of the measurement and control system,including the high efficiency working area,the highest working speed,the peak speed,the highest efficiency,the accuracy of torque control,temperature rise and so on.Through the above test results,it is proved that the test-bed measurement and control system designed can test the performance of pure electric vehicle powertrain drive system,and have good reliability.The feasibility of the evaluation method is verified by the analysis of the test data. |
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