Research On Bra King Energy Recovery Strategy Of Pure Electric Vehicle Driven By Four-wheel Hub Motors

Nowadays,society has been plagued by the large amount of energy consumption and environmental pollution caused by the large-scale use of traditional fuel vehicles.As the country has increased its support for new energy vehicles,new energy vehicles have received attention from people.Four-wheel hub motors independently drive electric vehicles as a new energy vehicle,which not only solves the pollution problem of fuel vehicles,but also omits part of the structure of traditional vehicles.On the one hand,it improves the economic performance of automobiles and the protection of the environment,on the other hand,it improves the efficiency of power transmission,which has become a new direction for future automobile development.The braking energy recovery of pure electric vehicles effectively improves the mileage of pure electric vehicles,and the braking energy recovery effect of electric vehicles independently driven by four-wheel hub motors is better.In this paper,it takes four-wheel hub motors independently drive electric vehicles as the research object,studies the power system matching of four-wheel hub motors independently drive electric vehicles,establishes a four-wheel hub motor independently drive electric vehicle power generation model,analyzes the influencing factors of the brake energy recovery of the hub motor,and puts up with the four-wheel hub Motor braking energy recovery strategy.First of all,the power performance parameters of the four-wheel hub motors independently driven by electric vehicles are determined.According to the relevant standards,the design index parameters for the performance of the four-wheel hub motor independently driven electric vehicle are proposed.The main parameters of the motor and battery are calculated using the vehicle parameters,and the appropriate motor and battery model are selected;the selected motor,battery and other parameters are determined by the AVL CRUISE software Carry out dynamic performance simulation.The results show that the maximum speed of the four-wheel hub motor independently driven electric vehicle meets the relevant requirements in GB/T 28382-2012"Technical Conditions for Pure Electric Passenger Vehicles".Secondly,it analyzes the force in the braking process of the four-wheel hub motor independently driven by the electric vehicle and the braking energy recovery power generation model.It analyzes the front and rear wheel braking forces to determine the "instability"conditions of the vehicle;establishes a four-wheel hub motor braking energy recovery power generation model,and uses genetic algorithms to solve multi-constrained nonlinear functions.The results show that:when the required braking force is small,the front axle motor alone drives the overall power generation efficiency;as the braking torque increases,the efficiency is the highest when the four motors are nearly evenly distributed;when the required braking torque is large,The braking torque of the rear axle motor is higher.Thirdly,the influencing factors of in-wheel motor regenerative braking are tested.By analyzing the energy flow of the in-wheel motor electric vehicle,the evaluation index of the regenerative braking test is proposed;the inertial simulation principle is used to test the influence of the in-wheel motor speed and battery SOC on the in-wheel motor regenerative braking.The test results show that when the speed of the in-wheel motor is less than 350 r/min,the reutilization rate is less than 45%;when the battery SOC is higher than 80%,the recyclability rate is lower than 45%;the average utilization rate in other areas is higher than 50%.%;For the recovery rate,the relationship with the SOC of the power battery is not obvious,but as the initial braking speed increases,the recovery rate increases;as the rated speed is exceeded,the recovery rate is basically maintained at about 90%.Finally,the braking strategy is simulated.It divides the braking intensity,and uses typical urban road speeds to analyze the rationality of common vehicle speeds and braking intensity;designs braking control strategies based on the influence factors of braking energy recovery,and cycle through different braking intensities and NEDC.Performing simulation tests under working conditions.The simulation results show that the braking energy recovery efficiency under the three braking intensities is greater than 30%;under NEDC cycle conditions,the regenerative braking control strategy saves 28kJ more energy than the AVL CRUISE control strategy.