The Analysis Of Passive Series Regenerative Braking Control Based On Energy Constraint Control

Vigorously promoting the development of electric vehicles is an important part of the national automobile industry layout,and the low energy density of the battery and the short driving range of the vehicle have become the main factors restricting its development.The development of regenerative braking technology provides a new way to solve this problem.Using the regenerative braking characteristics of the motor,the kinetic energy of the vehicle during the braking process is converted into electrical energy and stored in the energy storage unit for reuse to improve the energy utilization.The regenerative braking system mostly adopts the method of motor and hydraulic compound braking.This article focuses on the hybrid energy storage system and electromechanical braking force control in the passive series regenerative braking system.The specific work content is as follows:(1)Combined with the working process of the regenerative braking system,the energy flow is analyzed.The braking force control method is designed with energy constraints,which is settled by relationship between the vehicle deceleration and the rate of the ultracapacitor terminal voltage during the regenerative braking.For engineering requirements,the passive series hybrid energy storage system structure is determined,and the energy recovery process is analyzed to optimize the design;in addition,the traditional hydraulic brake system control algorithm is improved.(2)Through the force analysis of the braking process,due to the unique regenerative braking process of electric vehicles,a braking force distribution strategy based on fuzzy rules is proposed;secondly,the vehicle hydraulic braking system is modeled,which system model was calibrated using the vehicle supercharging experiment.(3)The system model based on the single-step series hybrid energy storage system and the three-step series hybrid energy storage system was built,and the verification of simulation was carried out in combination with typical working conditions;In order to further verify the feasibility of the system under the hardware environment,hardwarein-the-loop verification was carried out.The research results show that,considering the energy recovery efficiency under the single-step and three-step regenerative braking system,the fuzzy braking force distribution strategy is higher than that under the fixed ratio distribution,but the improvement of the three-step regenerative braking system is more obvious;compared with the single-step system,the single-step system has better braking comfort performance.