Automatic gear-shifting control method and system for two-gear transmission of electric vehicle

Abstract

The invention discloses an automatic gear-shifting control method and system for a two-gear transmission of an electric vehicle, and belongs to the technical field of electric vehicle gear-shifting control. The automatic gear-shifting control method comprises the specific steps that whether the gear-shifting condition is met or not is judged, if the gear-shifting condition is met, the gear-shifting mode is conducted, and transmission control unit (TCU) replaces a vehicle controller to control a driving motor controller, so that torque of the driving motor is reduced to zero torque according toa certain curve; in the zero torque, the TCU controls a gear-shifting executing mechanism to shift a gear down to a neutral gear; in the neutral gear, control torque is determined through the TCU byutilizing a certain algorithm, so that the rotating speed of a driving motor is adjusted to the target speed; After the target speed is reached, the TCU controls the gear-shifting executing mechanismto shift gear; a non-gear-shifting mode is conducted, torque is slowly increased to the torque corresponding to an accelerator signal according to a certain curve; torque reducing and torque increasing are conducted according to the certain curve, and the speed is adjusted through the TCU by using a torque mode, so that the speed adjusting time is reduced, quick gear shifting is achieved, abruptness caused by power interruption during gear shifting can be effectively alleviated, and the driving feeling is improved.

Description

technical field [0001] The invention relates to an automatic shift control method of a two-speed gearbox of an electric vehicle and a control system thereof, belonging to the technical field of shift control of electric vehicles. Background technique [0002] Most traditional electric vehicles are driven by a single-stage reducer, which mainly has the following problems: the maximum output torque is small, and the gradeability is insufficient; the fixed transmission ratio is insufficient for medium and high speed performance; the maximum speed of the motor is required to be high, the weight of the motor is relatively large, and the cost is relatively high In response to these problems, the two-speed gearbox can effectively combine the economy and drivability of electric vehicles. At present, when the existing two-speed gearbox is judged to meet the shifting conditions during the shifting process, it is directly in the working state of the drive motor. (The torque of the moto...

AI Technical Summary

Problems solved by technology

[0002] Most traditional electric vehicles are driven by a single-stage reducer, which mainly has the following problems: the maximum output torque is small, and the gradeability is insufficient; the fixed transmission ratio is insufficient for medium and high speed performance; the maximum speed of the motor is required to be high, the weight of the motor is relatively large, and the cost is relatively high In response to these problems, the two-speed gearbox can effectively combine the economy and drivability of electric vehicles. At present, when the existing two-speed gearbox is judged to meet the shifting conditions during the shifting process, it is directly in the working state of the drive motor. (The torque of the motor is not zero) when the gear is backed up, enter the neutral gear for speed regulation, put into gear after the speed regulation is completed, and directly respond to the accelerator signal, without considering the slow down torque before the back gear and the slow rise torque after the gear is engaged, which will cause the car to run at high speed Sudden loss of power (into neutral) during operation, and a large torque is suddenly given after the gear is completed, resulting in forward momentum, which gives people an obvious sense of frustration and seriously affects the driving experience; in addition, the existing methods of speed regulation generally rely on the motor. The speed adjustment mode is used for speed adjustment, and the speed adjustment time is long, resulting in a long time for shifting gears, which means a long time for losing power and affecting the driving experience

Images