Advanced shifting control of synchronizer mechanisms for clutchless automatic manual transmission in an electric vehicle

• A concept of clutchless automatic manual transmission for electric vehicle is introduced.
• The dynamic characteristics of synchronizer and synchronization process are analyzed.
• A robust position control scheme for the gear-shift actuators is proposed and validated.

On the basis of improving drivability and efficiency, an electric vehicle equipped with automatic manual transmission is a considerable framing. However, the conventional geared transmissions usually install automated clutch which require the hydraulic power in addition to the slippage in the clutch plate invoking some energy loss as well as wear. For this reason, a practical approach with respect to clutchless automatic manual transmission (CLAMT) and its gear-shifting control strategy for an electric vehicle was proposed by our research team. In order to determine the key factors affecting the gear-shifting operation of CLAMT, a dynamic model of the CLAMT driveline was developed and the dynamic characteristics of the transmission synchronizer during each gear-shifting phase were analyzed in this paper. The analysis indicates that the gear-shifting operation of CLAMT not only requires a power motor with the capability of rapid mode-switching and precise speed regulation, but also demands that the shift actuators have the ability of exact position adjustment and strong robustness against shift load variations. To realize rapid and accurate gear-shifting control, the key technique relating to the robust position control scheme for the gear-shifting actuators were described in detail and validated on a designed CLAMT test rig.