Gearshift and brake distribution control for regenerative braking in electric vehicles with dual clutch transmission

Abstract

To alleviate the problem of limited driving range per charge in electric vehicles, a dual clutch transmission based regenerative braking power-on shifting control system is proposed and investigated in this paper. Power-on shifting refers to the shift process where the power flow between the wheel and the power source is not cut off and could be maintained around a desirable value. This character is more important for regenerative braking than the normal driving conditions as the regenerative braking force from the motor accounts for a large part of the total braking force. Due to the difference between the normal driving condition and the regenerative braking process, existing normal driving shifting control strategies, which could introduce significant torque interruption, cannot be directly applied for regenerative braking. As a result, the energy recovery capability and efficiency are compromised. To solve this problem, a power-on shifting control strategy for regenerative braking is proposed as well as an energy-safety oriented braking strategy. To demonstrate the effectiveness of the proposed system, mathematical models are built and dynamic responses of the transmission system during braking both in up-shift and down-shift processes are presented. Moreover, the efficiency and recovery capability improvements made by achieving power-on shifting during regenerative braking are verified through a typical deceleration driving cycle and a specially designed daily deceleration scenario.