Regenerative Braking Control Theory And Experimental Research For Parallel-series Hybrid Electric Vehicle

Regenerative braking system of hybrid electric vehicle(HEV)is the difference from the traditional internal combustion engine vehicle braking system,and the braking system is one of the key devices in hybrid power automobile for fuel saving.It can save kinetic energy in the car braking deceleration or in the sliding process through the inversion power motor.The generated electric energy is stored in the cell,then the braking energy recovery is completed,and a regenerative braking force is produced.At the same time automobile fuel consumption and emission of pollutants are reduced in the regenerative braking system,but the vehicle deceleration and braking are also realized.Braking energy recovery have a significant effect on energy saving,emission reduction and driving distance extension,and so on.This paper was based on the Heilongjiang Natural Science Foundation project "Study on parallel-series hybrid electric vehicle optimized control and hardware-in-loop simulation".The study mainly focuses on the regenerative braking control strategy and control algorithm for parallel-series HEV.The control strategy has been verified by built the simulation platform and developed the regenerative braking test platform for the parallel-series HEV.The test results showed that the system had the efficient recovery of braking energy,at the same time,ensuring good braking performance.This work ensures the braking efficiency and realizes the high efficient braking energy recovery under several typical braking condition.The background and significance of HEV regenerative braking research are described firstly.The structure and characteristics of HEV drive system is introduced,as well as the current domestic and foreign research on HEV regenerative braking control strategy and test technology.This work analyzed the influencing factors on the braking energy regeneration process in HEV and the problems in the study.The paper took the regenerative braking system of the parallel-series HEV as the research object,and analyzed its structure,working principle,as well as the operating characteristics of the drive motor,the battery and other main components.This work established the main mathematical models for regenerative braking evaluation.This work performed the kinetic analysis for braking process of HEV.The overall vehicle dynamics model,the mathematical models of regenerative braking system assembly and variouscomponents were established.On this basis,this work studied the distribution relationship between the ideal front,rear wheel braking force and the actual wheel braking force.In this work,several issues were determined the vehicle braking force distribution principle,implementation and distribution methods based on the regenerative braking system characteristics of parallel-series HEV and three typical braking control strategy,including best braking feel,optimum braking energy regeneration and parallel braking.The regenerative braking control system belonged to the separated braking controller and vehicle controller.The braking controller controlled the mechanical braking.The vehicle controller controlled the regenerative braking.The CAN bus was used for the communication between the braking controller and vehicle controller.The paper presented the regenerative braking control strategy for parallel-series HEV based the input and output parameters and requirements of regenerative braking control system.The fuzzy PID control algorithms based on PID control were analyzed,fuzzy logic control algorithms which were widely used on the braking control process of HEV.Fuzzy controller was designed based on the proposed regenerative braking control strategy,control parameters of braking control system in parallel-series HEV.The control input,output,fuzzy rules were determined.This work also determined methods by which the fuzzy controller adjusted the PID controller parameters.Finally,fuzzy PID controller of the regenerative braking system in parallel-series HEV was designed with the cascade communication between the fuzzy controller and PID controller.Regenerative braking control strategy models of parallel-series HEV were established by MATLAB/Simulink software.Parametric models for each powertrain and braking system were established by AVL CRUISE software.The regenerative braking control strategy were simulated and analyzed by co-simulation platform of MATLAB/Simulink and AVL CRUISE.Typical braking condition,coasting condition and typical cycle driving condition were chosen.The simulation results had shown the variation among mechanical braking and regenerative braking torque,battery SOC,braking energy regeneration,braking energy regeneration rate and other parameters under different conditions.The paper developed a regenerative braking test platform of parallel-series HEV based on the chassis dynamometer.The platform took the dSPACE MicroAutobox as a real-time controller,the chassis dynamometer as the power absorption and loading device,the VCXvehicle communication module as the data acquisition device of test platform.The regenerative braking system control strategy models established in MATLAB/Simulink were downloaded in dSPACE MicroAutobox.The regenerative braking process control was performed by MATLAB/Simulink/RTW,dSPACE/RTI and ControlDesk software.The tests were performed by fuzzy PID control strategy on the test platform.Three operating conditions were chosen,including typical braking condition,typical steady state condition and coasting condition.Moderate braking intensity and different braking initial velocities were selected for the typical braking condition.The test results showed that the test system of the regenerative braking ran smoothly.Braking energy can be effectively recovered by fuzzy PID control strategy.Braking energy recovery in the three conditions can reach about 20%,25% and 60%respectively.This paper offered a new control methods and test platform for the research on the regenerative braking control system of parallel-series HEV.