Research on gear-change control technology for the clutchless automatic-manual transmission of an electric vehicle

A lightweight electric vehicle equipped with an automatic-manual transmission offers many advantages in terms of the transmission efficiency, the improvement in driveability, and the shift quality. A conventional automatic-manual transmission for a vehicle powered by an internal-combustion engine requires an electronically controlled clutch to isolate and engage the engine power for smooth gear changes, because of the high inertia of the internal-combustion engine. This makes the system complicated and, therefore, more expensive. Hence, a clutchless automatic-manual transmission with the advantages of a high efficiency, a low cost and a simple structure was adopted and developed in this paper. This study is focused on exploring the feasibility of a clutchless automatic-manual transmission adopted in an electric vehicle and proposes a gear-change control technique for a clutchless automatic-manual transmission, which includes identification of the model parameters, control of the synchronization speed during gear engagement, and motion control of the gear-change actuator mechanism. Theoretical analysis, simulation and experiment confirm that the designed control technique is able to achieve smooth gear shifting. Therefore, the feasibility of a clutchless automatic-manual transmission is verified.