| Energy conservation and emission reduction are the subjects of the automotive industry development nowadays.The development of new energy automobile is promoted by the growing awareness of the public and the continuous advancement of the electronic technology.As a kind of new energy automobiles,plug-in hybrid electric vehicle(PHEV)is the best choice for the transition to the clean energy vehicle.Energy-saving technology of automobiles is of great significance to improving the energy efficiency of vehicles.Based on the basic principles of automotive regenerative braking technology,the flywheel regenerative braking and the motor regenerative braking system are combined as a composite regenerative braking system in this paper,which can maximize the recovery of braking energy.The flywheel can effectively adjust the optimal operating point and motor peak of the engine,improving the energy efficiency.The main contents of this article are as follows:Firstly,lithium batteries,electric motors,and biomass-based diesel engines were as the main power sources,while the braking energy recovery system was as an auxiliary power source of the system.These two parts formed a composite energy source.Part of the kinetic energy can be converted into the mechanical energy of the flywheel,or the battery electrical energy through the generator when the vehicle brakes or decelerates,while it can be fed back to the vehicle as kinetic energy during acceleration.The key technologies of the flywheel energy storage,and the effects of the material,shape,speed,and mass of the flywheel on the state of energy storage were analyzed in this paper.Secondly,the characteristics of vehicle braking energy recovery were analyzed,such as the basis for energy recovery,brake energy utilization.It was mainly to recover energy during deceleration braking,while it was less recovered during emergency braking.The composite braking energy flow was analyzed.A single-stage planetary gear mechanism was selected as a power coupling and energy flow distribution device to reduce the loss of braking energy in the recovery process.Besides,the braking energy recovery characteristics of the flywheel were analyzed,theoretically verifying the feasibility of the flywheel energy storage device loaded into the vehicle powers.Based on the analysis of the energy-saving potential of the motor and the comparison of the three cycle conditions,the typical simulation in urban cycle conditions was confirmed.Thirdly,the basic parameters of the key components of the power system were determined through theoretical calculation and analysis.In addition,the mathematical model of the power train was established.Based on the relationship between the characteristics of the material and the state of energy storage of the flywheel,the basic specifications of the flywheel were determined compared with the parameters of the three flywheel energy storage devices.Finally,the three commonly used control strategies and their characteristics of PHEV were analyzed.The control strategy based on the rule was determined to manage the energy through comparative analysis.The simulation of the power train was done by the Matlab/Simulink and ADVISOR software to analyze the fuel economy and power of the vehicle.Results show that the work condition of the engine has been significantly improved by integrating the composite braking energy recovery system and the engine.The operating point is basically stable in the best efficiency area.At the same time,there is a peak-regulating effect on the motor.The braking energy recovery rate and the power performance of the vehicle are obviously improved. |
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