Research on Composite Braking Control Strategy of Four-Wheel-Drive Electric Vehicles with Multiple Motors Based on Braking Energy Recovery Optimization

Four-wheel-drive system with multiple motors has been one of the important development trends of electric vehicles, which has an important impact on the regenerative braking of electric vehicles. Aiming at the configuration characteristics of a composite braking system for the four-wheel-drive electric vehicle with multiple motors, this paper proposed a novelty composite braking control strategy based on braking energy recovery optimization. Firstly, the characteristics and constraints of braking dynamics of four-wheel-drive electric vehicles with multiple motors were analyzed. Secondly, the composite braking control strategy to optimize braking energy recovery was developed. The control strategy mainly optimized the motor braking of the front and rear axle according to the braking energy recovery efficiency within the range of motor braking to maximize the recovery of braking energy. And the motor and hydraulic braking forces were concertedly distributed to improve braking stability. Finally, the semi-physical simulation platform is used to verify the composite braking control strategy under single braking conditions and CLTC-P cycle condition. The test results demonstrate that the composite braking control strategy proposed in this paper can effectively improve braking energy recovery and braking stability.