Electric Vehicle Gear Shifting Torque Control
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Solution Overview
Problem
Electric vehicles experience a decrease in driving torque and delays in RPM synchronization during kick-down gear shifting, leading to responsiveness issues and a G-drop phenomenon, especially in equal-power sections.
Innovation Solution
A method of controlling gear shifting in electric vehicles that corrects motor torque by calculating the de-rating torque and synchronization ratio based on pre- and post-gear shifting RPMs, and adjusts the torque command to maintain acceleration linearity and prevent torque reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If kick-down gear shifting is performed in EV mode, then gear ratio is changed to increase acceleration, but motor torque decreases and responsiveness is delayed
Solution Approach 1:
The control device increases motor torque before gear shifting occurs (in anticipation of the shift) to compensate for the torque reduction that will happen during the shift. This preliminary torque increase ensures that acceleration is maintained throughout the gear transition rather than experiencing a drop in power delivery.
Solution Approach 2:
The control device applies a counteracting torque increase to prevent the harmful effect of torque reduction during gear shifting. By detecting the gear shift state and actively compensating with additional torque, the system counteracts the natural torque drop that occurs during equal-power section shifts, thereby maintaining acceleration linearity.
2Productivity
If gear shifting is performed in equal-power section, then gear ratio changes to improve acceleration, but RPM synchronization control is delayed
Solution Approach 1:
The control device begins torque correction before the gear shifting is complete, anticipating the RPM synchronization requirement. By pre-adjusting torque based on detected gear shift state, the system prepares the motor for the upcoming RPM change, reducing the time needed for synchronization.
Solution Approach 2:
The control device continuously monitors gear shift state and uses this feedback to dynamically adjust motor torque. This closed-loop control ensures that torque correction is applied at the optimal moment during the gear transition, minimizing synchronization delay while maintaining acceleration performance.
3Ease of manufacture
If conventional gear shifting control is used, then transmission efficiency is maintained, but G-drop phenomenon occurs during kick-down shifting
Solution Approach 1:
The control device uses feedback from gear shift state detection to dynamically adjust motor torque during the shifting process. This feedback mechanism allows the system to maintain transmission efficiency while preventing the G-drop phenomenon by compensating for torque changes in real-time based on actual shifting conditions.
Data Source
AI summary
A method of controlling gear shifting in an electric vehicle includes: determining whether or not an electric vehicle travels in an electric vehicle (EV) traveling mode; determining whether or not kick-down gear shifting is required in the EV traveling mode; determining whether or not acceleration linearity control is possible, in a case where the kick-down gear shifting is required; performing correction of a torque of a motor in a case where the acceleration linearity control is possible; and performing gear shifting in a transmission on the basis of the corrected torque of the motor.