Research On Power System Parameter Matching And Energy Management Strategies Of Dual Motor Four-Wheel-Drive Electric Vehicle

With the gradual aggravation of the problems of energy consumption and environmental pollution,energy-saving and environmentally friendly pure electric vehicles have become the mainstream research direction of the automobile industry in recent years.However,due to the inability of single-motor-driven vehicles to balance the relationship between power and economy,dual-motor four-wheel-drive vehicles have gradually received attention and become a research hotspot at home and abroad.This paper takes the dual-motor four-wheel-drive vehicle as the research object,matches the parameters of its power system,designs the drive control strategy and the brake energy recovery control strategy.The designed control strategy is jointly simulated and analysed based on MATLAB/Simulink and CRUISE under different operating conditions.The details are as follows:(1)Matching of powertrain parameters for the dual-motor four-wheel-drive vehicle.Advantages and disadvantages of different dual-motor drive system configurations are analysed.On the basis of the kinematic analysis of the whole vehicle,combined with the parameters of the whole vehicle and the performance demand indicators,the drive motor,power battery and gear ratio are parametrically matched.According to the results of parameter matching,the vehicle model of the dual-motor four-wheel drive vehicle is built in CRUISE software and simulated under different working conditions to verify the reasonableness of parameter matching.(2)Research on the drive control strategy of the dual-motor four-wheel drive vehicle.Based on the relationship between the accelerator pedal opening and the torque loading coefficient,three drive modes are designed.A fuzzy controller with acceleration intent recognition function and a fuzzy controller with drive mode recognition function are designed,and the demand torque is calculated by combining the size of the accelerator pedal opening.The driving modes of the independent front and rear axle drive systems are analysed,according to the working characteristics of the motors,a mathematical model aiming at the optimal utilisation efficiency of the two-motor drive system is established,and the optimal torque distribution control strategy for the two motors is designed.In order to improve the passing performance on low traction surfaces,the drive anti-skid control strategy is designed by analysing the wheel dynamics as well as control methods.(3)Research on brake energy recovery control strategy for the dual-motor four-wheel drive vehicle.Vehicle forces and braking force distribution during braking are analysed.Advantages and disadvantages of different brake energy recovery systems and brake force distribution control strategies are analysed.Motor braking is limited by analysing the factors affecting brake energy recovery.Based on the braking force distribution feasible region,a braking force distribution control strategy is designed.Three different braking modes,namely mechanical brake,motor brake and compound brake,are rationally classified.A fuzzy controller with vehicle speed v,battery SOC,and braking intensity z as inputs and motor braking duty ratio K as output is designed to provide rational control of motor braking duty ratio.(4)Simulation and analysis of drive and brake energy recovery control strategies.A joint simulation model is built based on MATLAB/Simulink and CRUISE to simulate and analyse the drive and brake energy recovery control strategy.The simulation results under WLTC conditions show that under the designed torque control strategy,the battery SOC variation is reduced by 3.19% and the range is improved by 3.42% compared with the commonly used torque control strategy.The simulation results of four different road conditions show that the designed drive anti-skid control strategy is able to effectively control the wheel skidding.The simulation results under four fixed braking conditions show that the designed braking energy recovery control strategy can make the motor braking and mechanical braking be controlled in a coordinated way,and can make the energy recovery.The simulation results under WLTC conditions show that the battery SOC variation is reduced by 18.86% and the range is improved by 20.62%.