Research On Four Wheel Drive Electric Vehicle Hybrid Braking Strategy Based On Driving Intention Recognition

Oil energy crisis and environmental degradation have a serious impact on people’s life,so this problem has got the attention of the whole society and the government,electric vehicles are produced under such a situation.Four wheel motor independent drive electric vehicle with its simplified traditional system,space saving,motor control flexibility compared with the ordinary electric car has got attention of the experts and scholars all over the world and through the efforts have achieved great results.In the key technology of electric vehicle,regenerative braking technology can be used to recover the braking energy,thereby increasing the driving range of electric vehicles.Electric vehicle with braking energy recovery device has two sets of braking systems,mechanical braking system and motor braking system.Due to the reasonable distribution of the two braking system,the electric cars can recover a lot of braking energy.,therefore,based on this consideration,the introduction of the driving intention to determine,through the driver’s intention to judge,to identify a variety of braking intention model,then,the matching between the two braking system is carried out according to the different braking modes.The specific research contents are as follows:(1)In this paper,the background of the research on the identification of motor drive,the intention of braking and the energy recovery of the four wheel hub motors are analyzed,and describes Current research status on the braking intention recognition and the recovery of braking energy.(2)The fuzzy parameters are analyzed and the fuzzy identification parameters are selected,they include the acceleration pedal opening,the brake pedal opening,the brake pedal opening rate and the vehicle speed,then the intention recognition model was established,and the six kinds of braking intention are identified,they include high speed emergency braking mode,high speed general braking mode,high speed gentle braking mode,medium speed emergency braking mode,medium speed nonemergency braking mode,low speed braking mode.(3)Through the ECE regulations,we get the range of the coefficient of dynamic coefficient which is in accordance with the requirements of this article.Then,according to the seven models of fuzzy recognition,the distribution relationship between the braking force and the mechanical power is set up.(4)Motor model,battery model,15 degrees of freedom vehicle dynamics model,wheel model are built by using MATLAB/Simulink platform,through the simulation of a variety of typical initial speed,the braking distance curve,the braking speed curve and the SOC curve are obtained to verify the effectiveness of regenerative braking strategy,through braking distance under the braking initial velocity specified in GB,to verify compliance of the braking strategy.Six braking modes identified by driving intention,the coordination of the mechanical braking force and the braking force of the motor is carried out according to different braking modes,and the simulation of the braking strategy is carried out to verify the effectiveness of the proposed strategy.