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Control Of Optimal Braking Torque For Machanical And Regenerative Braking Systems Of Hybrid Electric Vehicle

Posted on:2014-12-30Degree:MasterType:Thesis
Country:ChinaCandidate:B ShiFull Text:PDF
GTID:2252330392964266Subject:Control theory and control engineering
Abstract/Summary:PDF Full Text Request
The emphasis of research for hybrid electrical vehicle braking system is how toachieve optimum braking effectiveness and the maximum energy feedback, under thepremise of insurance the security and longitudinal stability during braking for hybridelectrical vehicle. In view of the control problem that braking security and stability as wellas energy regeneration for HEV braking system, a new design based on slip ratio ofoptimal braking torque for braking system is presented in this paper, and which is carriedout by mechanical braking system and regenerative braking system.First, in order to deal with the security and stability of the vehicle in braking, aoptimal braking torque based on a slip ratio is researched in this paper. The Luenbergerobserver is constructed to solve the ummeasurable vehicle speed of actual condition andthe unknown road condition, which produced by tire structure, external interference andvelocity factors. Then, optimal braking torque is introduced based observer by usingadaptive estimation algorithm. The convergence of observer for the theoretical analysisand simulation verification of is given in this paper. Meanwhile, theoretical analysis andsimulation results shows that the slip ratio and adhesion coefficient are controlled at theoptimum value for braking system under the optimal braking torque.Second, the control problem of security and stability in vehicle braking processunder urgency condition is studied. The optimum braking torque is carried out byhydraulic braking system. There are a lot of interferences in the actual working process ofhydraulic braking system, which is caused by dry friction and the pressure inside/outsideas well as the unmeasurable piston speed of wheel cylinder. With the performance ofinterference suppression for a reduced-order observer-based output feedback controller isproposed by utilizing design idea of Backstepping for hydraulic braking system,Theoretical analysis and simulation results shows that the actual output brake torque ofhydraulic braking system can accurately track the optimum braking torque.Third, the control scheme that optimum braking torque is coodinated by regenerativebraking system is researched in this chapter. AOH braking torque controller and regeneration braking torque controller are designed based a nonlinear mathematicaldynamics model for actuator of pneumatic braking system AOH model as well as energyfeedback system model, which can proper distribute optimum braking torque. Theoreticalanalysis and simulation results shows that the proposed control scheme can guarantee thesecurity and stability of the HEV braking process, in addition, the purpose of the energyfeedback is achieved.
Keywords/Search Tags:Optimum braking torque, Slip-ratio, Mechanical braking system, Regenerative braking system, Adaptive control, Observer
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