ABSTRACT Nowadays, the endurance mileage of electric vehicle is commonly short. For the purpose of enhancing the endurance mileage of 4WD electric vehicles, this paper proposes a new control strategy based on the generation efficiency of in- wheel motors. When the brake strength is low, the strategy defines the torque on which the motor has the highest generate efficiency as the upper limit of the braking torque of the front axle. What's more, the proportion of mechanical braking force is reduced. Because of these, the vehicle has a higher generation power. The simulation model is built up by using Matlab/Simulink and CarSim software, and the strategy is simulated under several driving cycles. The result shows that, comparing with the two traditional braking force distribution strategies, the new strategy can obviously improve the regenerative efficiency. INTRODUCTION Because of the restriction of the battery technology, the electric vehicles commonly have deficiency in endurance mileage, and recharging is not convenient. As a result, the electric vehicles are mostly used in urban areas. When driving in urban areas, the vehicles brake frequently and the braking strength is commonly low. To enhance the endurance mileage of electric vehicles, the power generation efficiency in low braking strength should be firstly raised. Equipped with in-wheel motors, the 4WD electronic vehicles could get more flexible arrangements [ 1] and the output torque of driving wheels on both sides could be controlled and measured independently [ 2]. Therefore the maneuverability of electric vehicles gets largely improved. The property of in- wheel motors deeply influences the regenerative braking and the energy efficiency of the vehicles.Many experts and research institutions have made some researches about regenerative braking. Hiroshi Fujimoto established a method to coordinate control of regenerative braking and tire slip coefficient based on electric vehicles equipped with in-wheel motors, and verified it by simulation [3]. Joseph Hartley built up a strategy to contribute brake force based on fixed proportion and verified it on real vehicle test [ 4]. Eric Krueger established a control strategy based on slip coefficient judgment and reduce the decelerations disturbances caused by reductions in regenerative brake torque [ 5]. Considering the varying property of the generation efficiency of in-wheel motors and the characteristic of 4WD electric vehicles, this paper proposes a new regenerative braking control strategy based on the generation efficiency of the motors. The strategy firstly improves the regenerative efficiency in low braking strength and reduces the proportion of mechanical braking force so that the vehicle can get a higher regeneration power. The simulation model is built based on the Matlab/Simulink and CarSim software. Besides the strategy is simulated based on several driving cycles and compared with the two traditional braking force distribution strategies. The result shows that the new strategy can obviously improve the regenerative efficiency. The paper firstly compares the regenerative efficiency of the two traditional braking force distribution strategies; secondly, the new regenerative braking control strategy is proposed in consideration of the power generation efficiency of the in- wheel motors; then, a simulation based on MATLAB/ Simulink and CarSim is conducted and the simulation results is presented; finally, conclusions drawn from simulation result are presented. The Regenerative Braking Control Strategy of Four- Wheel-Drive Electric Vehicle Based on Power Generation Efficiency of Motors2013-01-0412 Published 04/08/2013 Wenkai Xu, Hongyu Zheng and Zongyu Liu Jilin Univ Copyright © 2013 SAE International doi:10.4271/2013-01-0412Downloaded from SAE International by Univ of Nottingham - Kings Meadow Campus, Friday, August 10, 2018TRADITIONAL BRAKING FORCE DISTRIBUTION STRATEGY There are two typical kinds of braking f