Line Braking Torque Allocation Scheme for Minimal Braking Loss of Four-Wheel-Drive Electric Vehicles

In four-wheel-drive electric vehicles, appropriate distribution of braking torque could increase the regenerated power. However, existing online distribution methods did not consider comprehensively about tire losses and its cooperation with hydraulic braking. Thus, a motor- hydraulic online braking torque allocation scheme that minimizes electromechanical and tire losses is proposed. The online distribution is solved by discussion and polynomial fitting. Calculation results show that the proposed scheme has a relatively high efficiency for either nominal or mass/center of gravity changed vehicle parameters. Finally, co-simulation results of Carsim and Simulink show the effectiveness of the proposed method under different driving cycles; the efficiency enhancement could be 4.3% in high-speed-driving cycles and 1.5% in low-speed-driving cycles.