System Integration And Coordinated Control Of Frictional Brake And Electromagnetic Brake Of Vehicle

Even after years of development the control function of automotive hydraulic braking system is constantly reinforced, its essence as the friction brake remains unchanged which usually accompany by heat fade under continuous braking and braking noise. To improve the braking efficiency of automotive hydraulic braking system, a concept of integrating the electronic hydraulic brake and electromagnetic brake has been proposed so as to give full play to the advantages of electronic hydraulic brake and electromagnetic brake which will enhance the safety as well as energy-saving and environmental protection of the passenger cars. Currently, both the domestic and foreigner scholars have made some progress in research of the frictional and electromagnetic integrated braking system with an emphasis on the dynamic characteristics analysis of electronic hydraulic brake, the finite element analysis of the electromagnetic brake’s performance, the nonlinear control method of electronic hydraulic brake and electromagnetic brake, the anti-lock control or vehicle stability control on the basis of the electromagnetic brake,the structural design and parameter optimization of frictional and electromagnetic integrated braking system, the analysis of the braking performance during the joint work of friction brake and electromagnetic brake,and so on. Most of the domestic and foreign technical literatures fail to offer a study of the energy-saving optimization design, the coupling nonlinear characteristics analysis, the braking force distribution method, the braking mode switch control and the coordinated control under emergency braking of the frictional and electromagnetic integrated braking system. To address these issues, the study work of this paper is as follows:The theoretical computational methods for the distribution of the exciter field, eddy current field and air-gap field of the electromagnetic eddy current brake and permanent magnet eddy-current brake were tablesd and their accuracies of theoretical calculation methods were verified through experiments and finite element numerical calculation methods so as to systematically investigate the influence of exciter field and eddy current field on the distribution of air-gap field. Then the physical mechanism of eddy current magnetic effect was revealed and the eddy demagnetization effect theory was improved. On the basis of the redefinition of eddy demagnetization effect theory, the dynamic mathematical model of electromagnetic brake could be obtained precisely, the braking characteristics of electromagnetic brake could be explained and its braking performance could be predicted in design process.The dynamic mathematical models for electronic hydraulic brake, electromagnetic brake and vehicle baking were established. The coupling nonlinear model for the frictional and electromagnetic integrated braking system was deduced adopting the power bond graph method. The rapid prototyping platform of frictional and electromagnetic integrated braking system based on National Instruments was set up and an experimental research on its coupling nonlinear characteristics was offered. Experimental research show that the coupling nonlinear model of the frictional and electromagnetic integrated braking system is correct and effective which can be directly used for studying its distribution method of front and rear’s braking force and also be used as the mathematical models for braking mode switch control and anti-lock braking coordinated control through appropriate simplification.The energy consumption models of electronic hydraulic brake and electromagnetic brake were established respectively. The influence of system parameters and structural parameters on the energy consumption characteristics of electronic hydraulic brake and the influence of structural design parameters and operating parameters on the energy consumption characteristics of electromagnetic brake were also analyzed respectively. The energy-saving optimization design mathematical model of the frictional and electromagnetic integrated braking system was set up by taking the energy consumption under ECE-EUDC driving cycle as the major optimization objective and its analysis of illustrative example was carried out with genetic algorithm. Optimization results indicate that the energy consumption of electronic hydraulic brake and the volume of accumulator would be reduced effectively under the premise to ensure braking performance of the electronic hydraulic brake and the energy efficiency characteristics of electromagnetic brake would improve significantly if the low energy power zone of energy consumption power curve with vehicle speed attempt to include the initial brake speed range of typical urban driving cycle in the premise of completing the typical urban operating conditions using electromagnetic brake.The safety characteristics of electronic hydraulic brake was researched and the distribution method of front and rear’s braking force for the frictional and electromagnetic integrated braking system under the friction braking mode was raised. The impact of thermodynamic property on electromagnetic brake’s energy consumption was studied and the distribution method of front and rear’s braking force under the electromagnetic braking mode was proposed. The influence of ECE R13 braking regulations on the front and rear’s braking force distribution was analyzed and the distribution method of front and rear’s braking force under the integrated braking mode was put forward. The simulation study show that the distribution method of front and rear’s braking force under these three braking modes can significantly improve the energy consumption characteristics and safety characteristics of the frictional and electromagnetic integrated braking system.The switch control strategy of the frictional and electromagnetic integrated braking system was proposed and its hybrid Petri network model was established to analyze its stability in the process of braking mode switch by means of Lyapunov function method. The coupling controller of frictional and electromagnetic integrated braking system was designed and an experimental research on the braking mode switch control was conducted. Experimental research indicate that the wheel longitudinal slip ratio would be always lower than the optimal slip ratio in the switch control process of braking mode and at the same time the electromagnetic brake follow the driver’s braking intention and electronic hydraulic brake mainly provide certain braking strength which can ensure the stability and improve the comfort in the switch process of braking mode.The anti-lock braking model of frictional and electromagnetic integrated braking system was set up and the layered coordinated controller for anti-lock braking was designed. The hardware in-the-loop simulation platform of frictional and electromagnetic integrated braking system was also established based on National Instruments to carry out the research on its anti-lock braking performance. The hardware in the loop simulation study show that using electromagnetic brake replace the low-performance electronic hydraulic brake to estimate and control the optimal slip ratio in the process of anti-lock braking control while low-performance electronic hydraulic brake system would only provide a certain amount of braking intensity which could also fully realize the same anti-lock braking control effect of high-performance electronic hydraulic brake system.