A Novel Torque Distribution Strategy for Distributed-Drive Electric Vehicle Considering Energy Saving and Brake Stability

This paper presents a novel torque distribution strategy (TDS) and a modified regenerative braking strategy (MRBS) for distributed-drive electric vehicle (DDEV) considering energy saving and brake stability. The presented TDS minimizes the energy consumption from battery in driving process. In order to overcome the shortcomings by using polynomial approximation for motor efficiency and the local minima problem, an exhaustive search method (ESM) is proposed to obtain the optimal front-rear torque distribution ratio. First, the power summation of four in-wheel motors is selected as the cost function of the optimization problem. Second, the ESM is designed to obtain the optimal torque distribution ratio according to current torque demand and motor speed based on motor efficiency map. Maximum motor torque and tire-road conditions are taken as constraints. Third, a MRBS is proposed to improve energy recovery performance by take ECE R13 and motor efficiency into account. In order to improve computational efficiency, the optimized ratio for every achievable motor operation point is stored as a 3-dimension look up table. Finally, simulation experiments based on MATLAB/Simulink are carried out to verify the effectiveness of the proposed torque distribution strategy under NEDC and UDDS driving cycle. The simulation results show that the proposed TDS can improve the energy efficiency by 5.3% under NEDC and 5.5% under UDDS than even-drive strategy.