Abstract: A two-speed automatic transmission used in electric sport utility vehicle was developed to improve the performance of the propulsion system of the vehicle. The motor active synchronization were researched using gear ratio choice principle and shift change control algorithm. Simulation results show that the two-speed automatic transmission reduces the maximum torque demand, the motor running speed and mechanical noise, and improves driveline efficiency. The bench tests show that the motor active synchronization control reduces the power interruption time, and helps the transmission achieve a high shifting quality.

Key words: pure electric vehicle, two-speed transmission, fixed ratio reducer, motor active synchronization