Optimal regenerative braking torque of permanent-magnet synchronous motor in electric vehicles

This study investigated a method to determine the optimal regenerative braking torque with maximum energy recovery at given speed, which is essential for the regenerative braking control of electric vehicles. The method is based on the loss modelling of a permanent-magnet synchronous motor (PMSM) system, which consists of electric motor and inverter. The system-loss model is established based on a PMSM mathematical model including iron loss and is used to derive the optimal regenerative braking torque symbolic formula. In addition, the parameter sensitivity of the optimal regenerative braking torque is analysed and a method for online parameter identification is used to obtain the actual parameter values in real time. Thus, the accuracy and adaptability of the optimal regenerative braking torque during the motor-operation process is improved. The analysis results are validated through simulation and bench tests.