Study On Brake Force Dynamic Coordinated Control Strategy For Electric Vehicles

This paper studies the electric vehicles brake control system, majoring in the braking forcecoordinated control strategy during brake mode switch. Electric vehicles have two entirelyseparate braking system: motor braking system and hydraulic braking system, thus they havethree operating brake modes: motor braking alone, hydraulic braking alone and unitedbraking mode. During braking, combined with the vehicle information (such as speed,motor speed, and the battery SOC value) selected a corresponding mode for braking. Whenswitching, due to the different dynamic response characteristics of motor and hydraulicbrake system, the actual total brake torque has fluctuations, comparing with driverexpectations of the braking torque. The fluctuations affect the driver’s brake feel, causingbraking comfortlessness.The goal of this paper is to minimize braking force fluctuations during braking modeswitch of electric vehicles. Based on the dynamic response characteristics of motor andhydraulic brake system, this paper carried out the following work:1. Introduced the overall layout of the regenerative braking system, analyze the dynamicresponse characteristics of the motor and hydraulic brake system from the theoretical andexperimental method, comparing the dynamic response characteristics of the different brakesystems, and fitting out of the motor system transfer function, all of these laid the foundationfor coordinated control strategy for electric vehicles.2.Based on hierarchical design ideas, put forward the overall structure of the electricvehicles brake control system, the control system as the core of a coordinated controlstrategy, including the driver braking intention recognition strategy, mode switching strategy,brake energy management strategy and dynamic coordinated control strategy. Thecoordinated control included active compensation based on fuzzy PID control for motorbrake system and fluid pressure compensation based on model matching control, twobraking force work together, so as to minimize fluctuations in the actual braking force toensure brake comfort. 3. Based on AMEsim and Matlab/Simulink,developed electric vehicles braking forcedynamic coordinated control system co-simulation platform, three braking conditions suchas braking for low intensity, moderate-intensity brake, gradient strength, respectively ofoffline simulation, through the presence or absence of the coordinated control of thesimulation results verified by comparing the effectiveness of the control strategy.4. On the foundation of the original conditions, built a dynamic coordinated controlhardware in the loop test platform based on of xPC system, in order to verify theeffectiveness of the strategy for the electric cars braking force, selected the same threeconditions test validation of offline simulation, whether coordinated control test resultscompared to verify the effectiveness of the control strategy...