Regenerative Braking Torque Allocation Strategy for Dual-Rotor In-Wheel Motor Drive Electric Vehicle Based on the Maximum System Energy Recovery

The dual-rotor in-wheel motor (DRIWM) drive electric vehicle has multiple braking modes. Determining how to select the most suitable braking mode for the current driving conditions and dynamically allocate the regenerative braking torque of the inner and outer motors is the key to achieving maximum energy recovery. On the basis of regenerative braking characteristic analyses of the DRIWM, the switching rules of the vehicle braking modes were designed based on the optimal system efficiency, and the specific working ranges of various braking modes were determined. According to the efficiency characteristics of the inner and outer motors, a regenerative braking torque allocation strategy based on the principle of maximizing the system energy recovery was proposed in the dual-motor coupled regenerative braking mode. The simulation results show that, during the entire CLTC-P cycle condition, the three regenerative braking modes of the DRIWM can effectively recover braking energy within their designed working ranges. Moreover, both the inner motor and outer motor can operate at the best efficiency when they undertake the optimal braking torque to achieve the maximum braking energy recovery. The experimental results show that a variable voltage charging scheme for the DRIWM is adopted, which can further ensure that both the inner and outer motors can simultaneously store energy with the maximum efficiency to the power battery pack.