| In the environment of energy shortage and environmental pollution,it is imperative to introduce energy saving and environmental protection technology to the automobile industry.With zero pollution technology,regenerative system has become the mainstream vehicle energy saving technology:The technology can store the energy in the brake under the premise of ensuring safety,and return to the vehicle power system as an auxiliary power.The regeneration system can significantly improve the fuel economy of vehicles in the process of suburban or lower normal slope.The regeneration system can significantly improve the fuel economy of vehicles in the process of suburban or downhill.When equipped with regenerative system for tractor-semitrailer vehicle,two problems need to be solved:the problem of multi-axis power distribution,the rational distribution of mechanical power and regenerative braking force.This paper is based on the prototype of tractor-semitrailer vehicle.The purpose is to design an energy decoupling regenerative braking system without affecting the original power system and ensuring the braking safety.Based on MATLAB/Simulink software platform,this paper has completed the following work:(1)The braking process of tractor-semitrailer vehicle is analyzed,the dynamic load of wheel is calculated,and the ideal braking force distribution model considering load transfer is established.The basic structure of hydraulic regeneration system is analyzed,and an energy decoupling regenerative braking system suitable for multi-axle vehicle energy recovery is designed.(2)According to the parameters of the whole vehicle,the structural forms of the main components of the system are determined,and the matching methods of the key parameters of the hydraulic pump/motor and hydraulic accumulator are given.The design goal is to achieve synchronous drive and ensure the reliability of regenerative braking.The torque and speed controller is developed for the regenerative system using PID control technology,and the response simulation analysis of the controller is carried out to verify the feasibility of the design.(3)The influence factors of regenerative braking process are analyzed,and the regenerative braking force control strategy is designed based on logic threshold control.On the basis of this,the corresponding fuzzy rules are formulated by taking the vehicle speed,accumulator energy storage state and brake demand as inputs,and the regenerative braking force distribution coefficient as output,a regenerative braking force controller based on fuzzy control is designed by using fuzzy toolbox.(4)The simulation model of that whole vehicle is established in MATLAB/Simulink software.The typical braking and driving conditions are designed,the C-WTVC cycle conditions of heavy vehicles are selected.The regenerative braking system is simulated,and the regenerative braking performance is evaluated by energy recovery rate and driving contribution rate.The simulation results show that when the regenerative system has a state transition,the vertical force of the traction seat under the logic threshold control strategy has a large fluctuation,and the control performance is obviously lower than that of the fuzzy control strategy.At the same time,under a variety of simulation conditions,the regeneration braking system with synchronous drive can meet the braking and driving requirements,effectively recover energy,and improve the vehicle energy utilization rate.This paper provides a reference for the promotion and research of hydraulic regeneration system. |
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