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.

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Based on the characteristics of the back electromotive force (back-EMF), the rotor position information would be detected. Hence, the main theme of this paper is to design a practical approach to detect the zero cross point (ZCP) of back-EMF through virtual neutral voltage for sensorless brushless direct current (BLDC) motor drives. In contrast to conventional methods, the real neutral voltage of motor is not needed. In order to compensate the phase delay of the back-EMF due to low-pass filter (LPF) under different speeds, a voltage-controlled phase shifter, consisted of hysteresis comparator and voltage-controlled resistor (VCR), is proposed in this paper. The detail circuit model is introduced and some experimental results obtained from a sensorless prototype are shown to confirm the practicality of proposed senosorless drive method.