The Torque Distribution Control Of Front-and-Rear Independent Drive 4WD Electric Vehicle Based On Multi-Driving-Restraints

At present,as people gradually realize the importance of environmental and energy issues,electric vehicle have become an iconic industrial product in the new era.But with the increase of people’s demand for material life,how to achieve the solid position of electric vehicle to replace traditional fuel cars has become the growing concern of many scientists and technician.Multi-motor-driven four-wheel-drive(4WD)electric vehicle are one of the many attempts.For four-wheel-drive electric vehicle,how to effectively utilize the characteristics of multi-motor to improve the performance of vehicle has become one of the research hotspots.In this paper,Single Motor Front and Single Motor Rear Independent Drive(SFSRID)dual-motor 4WD pure electric vehicle is taken as the object,and its drive control of the vehicle under economic,dynamic,and safety constraints is studied.A multirestraint torque distribution control strategy(MRCS)including optimal distribution of efficiency,fuzzy recognition of torque compensation,and anti-slip torque correction is proposed.A series sufficient simulation tests is performed to verify effectiveness of the strategy.Firstly,analyzed the principle and characteristics of the power system of the SFSRID4 WD electric vehicle.The power system parameters are matched according to the design parameters and performance indicators of the vehicle.Based on the Matlab / Simulink,the key components of the vehicle are modeled and the forward simulation model of the vehicle is built.Secondly,analyzed three basic drive control issues of SFSRID 4WD electric vehicle which about economic anxiety,power improvement and safety assurance,then proposed a multi-restraint drive control strategy(MRCS).The strategy is mainly based on the torque distribution of optimal efficiency,supplemented by fuzzy identification torque compensation and anti-slip safety torque correction,so as to effectively solve the problems of economic,dynamic and stability constraints.Aiming at economic restraint,a basic torque distribution based on optimal efficiency was proposed.The efficiency models of the key components of the power system(motors,final drive,and power battery pack)are analyzed separately,and the system efficiency model is established.Based on this,a nonlinear optimization equation is established with the goal of optimal system efficiency.A feasible spatial discrete algorithm is used for solving.Aiming at dynamic restraint,A fuzzy torque compensation strategy based on driving intention recognition is proposed.This control strategy builds a double-layer fuzzy controller to realize the identification of driving intention and the compensation of torque.Aiming at safety restraint,a correction strategy of anti-slip torque distribution based on the target slip rate is proposed.This control strategy is based on a magic tire model and a seven-degree-of-freedom vehicle model,and a target slip rate PI controller is established to control the front and rear axle slip rates.Finally,verifying the MRCS drive control strategy of vehicle by series simulation tests.Tests on acceleration at different accelerator pedal change rates shows that the acceleration performance is improved under torque compensation strategy.Tests on uniform roads with low Adhesion coefficient and combined roads with high and low Adhesion coefficient shows that under the anti-slip correction strategy,the vehicle speed on the low attachment roads is significantly increased,and the combined road can quickly complete the anti-slip response.It is verified that the effectiveness of the anti-slip correction strategy on improving vehicle stability and power performance.Comparative verification tests of MRCS,average torque distribution,and load-based distribution control strategy on different typical drive cycles shows that MRCS can effectively improve the vehicle’s fuel economy performance.The energy consumption per 100 kilometers decreased by 9.55%,and the cruising range reached 550 km under NEDC cycle,which proved that it has good effects in terms of economy,dynamics and safety and stability.