An efficient braking energy recovery strategy based on differential game for hybrid electric truck considering electromechanical thermal dynamic

Brake failure is one of the main causes of truck safety accidents under long downhills. Frequent braking increases the risk of brake drums and motor thermal failure. Hence, how to coordinate the motor and pneumatic braking torque to reduce the motor and brake drums temperature rise in case of limited battery recovery capacity is a challenging task. In this paper, an efficient braking energy recovery strategy using differential game optimization is proposed for hybrid electric truck under long downhills. Firstly, the model is established considering hybrid electric power system and temperature rise of the motors and brake drums. Then, combining with real-time slope information and vehicle status, a non-cooperative two-player game model of motors and brake drums temperature rise is constructed, and the optimal braking torque distribution is obtained based on Nash Equilibrium. The proposed strategy is verified in two specific long downhill cycles. The results indicate that the proposed strategy has well control performance and can effectively suppress the temperature rise of the motors and brake drums. The sum of HT under the proposed strategy is 16.09%, 14.92% and 1.85%, 2.27% lower than the rule and Pontryagin's minimum principle under two driving cycles, respectively. The above results fully validate the superiority of the comprehensive performance of the proposed strategy.