摘要
该文研制了基于液压储能器的制动能量回收试验台,试验台用飞轮模拟车辆的转动惯量,利用液压泵回收能量,将能量存储于蓄能器.该文基于上述工作原理完成了试验台零部件选型和支撑结构的设计,同时基于STM32单片机设计了控制系统硬件,并开发了控制程序,可实时测量转速和蓄能器压力信号.该试验台能够模拟制动能量回收过程,分析不同条件下的能量回收和释放过程.
Abstract
[Objective]The regenerative braking system is a crucial component of electric and hybrid electric vehicles.Demonstrating the working process of this system to students is essential to helping them understand the underlying principles.Given the limitations of real vehicle regenerative braking systems,which do not exhibit the energy recovery process,and the absence of experimental test beds to display the working process,a regenerative braking system simulation test bed is developed.This test bed,designed with specific machinery and control systems,is used to illustrate the working principles of a hydraulic regenerative braking system.[Methods]The experimental test bed simulates the vehicle's moment of inertia using a flywheel group.A hydraulic pump is used for energy recovery,and the recovered energy is stored in an accumulator.Key components are selected according to the working process.The size of the flywheel group is calculated based on the vehicle mass,tire radius,and maximum speed.The pump specifications are determined based on the initial braking speed and maximum braking distance.The accumulator capacity is calculated according to the total energy of the vehicle,which ensures that energy can be stored in the accumulator.The mechanical support of the test bed is designed based on numerical simulations.This design is determined through a comparison of the static stress analysis with the yield strength of the materials.The control system,built around an STM32 microcomputer,includes both hardware and software components.The system receives speed and accumulator pressure data from the corresponding sensors and controls the clutch and electromagnet by toggling the power of the electromagnetic directional valve.To enhance the intuitive experience during the experiment,the MCGS configuration screen is used as the display module.The screen can communicate with the STM32 microcontroller through the Modbus protocol,enabling real-time data display with data curves using a graphical interface design.The system's feasibility is validated through experimental tests,which demonstrate that the designed system can simulate the braking energy recovery and release processes under various speed conditions.[Results]The experimental results show the following:① Upon the activation of the regenerative braking system,the vehicle's kinetic energy can be stored in the accumulator within 8 s,and the flywheel can stop completely.(2)Under the action of the energy recovery system,the flywheel speed gradually decreases while the accumulator pressure gradually increases.③ The flywheel group reaches a maximum speed of 670r/min when driven by the accumulator pressure.[Conclusions]The design of the machinery and control system for the regenerative braking system based on a hydraulic accumulator successfully demonstrates the working principles of a hydraulic regenerative braking system.The experimental results indicate that the microcontroller-based control system meets the requirements at a low cost.The regenerative braking system can independently achieve braking and enable the analysis of the energy recovery and release processes under different speed conditions.Additionally,this experimental system positively impacts students'understanding of regenerative braking systems and can be used to improve the efficiency of such systems.
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