| Global energy and environment system are facing huge challenges,and the traditional automobile,which exhaust the carbon dioxide and consume the fossil oil,need a revolutionary change,so the development of new energy automobile has become the consensus of all countries in the word and the automobile industry.As the technical means of the emission reduction and fuel economy further improvement for new energy automobile,regenerative braking technology is the focus in the study of new energy automobile.Regenerative braking system is from the motor participation in the traditional braking system,so it has to both address problems about the allocation and the coordination of motor brake and hydraulic brake.Based on the cooperation with enterprise project,this thesis researched a electric servo brake system applied in the new energy vehicles,and the researches carried on are as follows:1.The vehicle configuration has been analyzed;the composition and functions of the electric servo brake system have been analyzed,then the inputs and outputs of brake controller are introduced,and based on the characteristics of the servo system,the control structure and requirements of electric servo brake system have been proposed.Through the analysis of the brake system of the main working process and failure mode,it is concluded that the electric servo brake system is the full decoupling configuration and able to achieve regenerative braking.2.In order to get the pressurization ability and performance of tandem motor cylinder in the electric servo brake system,from the characteristics of test vehicle and the property of the coordination of motor brake and hydraulic brake in the process of regenerative braking,the brake test scheme has been designed.In accordance with the test process,tests have been carried on drum dynamometer and road as follows:fixed brake pedal test,high SOC brake test,changed brake pedal test and shift switch brake test.The data associated the brake,such as motor torque and brake wheel cylinder pressure,were analyzed,and the pressurization ability and performance was obtained.3.The working principle and performance of brushless direct-current motor(BLDC)and the ball screw,the structure of slave cylinder have been analyzed,in addition the main parameters of BLDC and ball screw which influence the work performance have been carried on the simulation analysis.On the basis of the average velocity and the maximum velocity of slave cylinder,making the braking deceleration and brake pedal speed in the typical working condition and emergency braking condition as the reference index,the parameter design process of the tandem motor cylinder was put forward.The model of BLDC and ball screw were selected,and preliminary parameters were determined.4.Based on the AMESim simulation model and real vehicle brake test data,the gear reduction ratio and the pitch of ball screw were determined.The electric servo brake system was simulated on the AMESim-Simulink platform,then the results showed that the hydraulic braking force can increase rapidly and satisfy the braking demand and pressurization requirements. |
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