| Since the 21 st century,the energy and environmental crises have brought great challenges to the development of countries around the world.Promoting the development of new energy vehicles has become an effective measure to promote energy conservation and emission reduction planning,and the new energy vehicle industry has become an important strategic layout for many countries.A reasonable operating temperature can improve the efficiency of the drive motor,extend the service life of the drive system,and improve the range of the vehicle,which is of great significance to the performance improvement of new energy vehicles.The electromechanical-hydraulic power-coupled electric vehicle is a new configuration of electric vehicle with electromechanical hydraulic coupler as its core,and the design and matching of its cooling system is an important basic research for subsequent product development and application.In this paper,the following research is conducted on the cooling system of the drive system of the electromechanical-hydraulic power-coupled electric vehicle.The hydraulic cooling scheme of power-coupled electric vehicle is designed.According to the cooling system structure principle,combined with the unique mechanical energy,electrical energy and hydraulic energy coupling characteristics of the electro-mechanical-hydraulic coupler,a new hydraulic cooling system is designed to match the corresponding hydraulic circuit for different operating conditions,to meet the needs of the vehicle under multiple operating conditions such as warm-up,parking and parking energy storage,and through the hydraulic valve to realize the mode switching in different states;with the help of hydraulic accumulator,the system is completed while With the help of hydraulic accumulator,the hydraulic booster and braking energy recovery functions are realized while the cooling system is completed;the parameters of the cooling system are matched and the selection analysis is carried out through theoretical calculation.The thermodynamic model of the cooling system was established and the design function of the cooling system was verified and analyzed.The cooling system model was established by AMESim software,and the tilt angle range of the swashplate based on the cooling demand and hydraulic booster demand was analyzed to verify the hydraulic booster function and brake energy recovery function of the cooling system.The results show that the cooling system can meet the cooling requirements of the drive train under different conditions,the hydraulic booster function effectively reduces the loss of the drive train and the energy consumption of the battery,and the brake energy recovery function realizes the recovery of the braking energy,relieves the limitation of the accumulator volume on the hydraulic booster,and effectively extends the duration of the hydraulic booster function.A Simulink-based control model for the cooling system was established.The cooling system valve position control strategy is built,and the hydraulic valve position matching control is carried out for different operating conditions,and the switching of different operating modes such as hot engine,parking and parking accumulator is realized by Stateflow;the heat generated by the drive system is taken as the disturbance quantity for temperature control,and the fuzzy PID temperature control strategy is designed to intelligently control the cooling fan speed.The fuzzy PID control strategy effectively improves the cooling fan temperature regulation ability,realizes the swashplate tilt angle correction based on the cooling demand,effectively reduces the temperature fluctuation range of the cooling system,and reduces the maximum system temperature from 64.5?to 58.5?,which proves the effectiveness of the cooling system design scheme. |
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