Electric Motor Controller Torque Transition for EV Shifting Impact
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Solution Overview
Problem
Quick shifting operations in electric vehicles often result in inadequate mitigation of impacts due to mismatched rotational speeds between the electric motor and the clutch disk, leading to significant torque changes and resulting impacts during gear shifts.
Innovation Solution
An electric vehicle system that includes a shifting state detecting device, an estimating device, and a motor controller to manage the transition between rotational speed control and torque control, ensuring a smoother transition by controlling the electric motor to align the angular velocities of upstream and downstream rotary members and adjusting torque output to minimize impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shifting operation is performed quickly, then the productivity of gear shifting is improved, but the impact caused by shifting cannot be adequately mitigated due to insufficient rotational speed control time
Solution Approach 1:
The system performs preliminary rotational speed control before the shifting operation is completed. The rotational speed control is executed during the shifting process to ensure that the rotational speeds are matched before the gear engagement occurs, thereby preventing shifting impact while maintaining quick shifting operations.
Solution Approach 2:
The control system acts as an intermediary between the driver's quick shifting input and the mechanical transmission system. It introduces a control mediation layer that manages the rotational speed matching during the shifting process, allowing quick shifting while mitigating impact through controlled speed synchronization.
2Speed
If the rotational speed control is switched to torque control quickly, then the response time is improved, but a great impact is generated due to significant torque changes
Solution Approach 1:
The system dynamically adjusts the control mode based on the shifting state. During the shifting process, it maintains rotational speed control rather than immediately switching to torque control. The switching from rotational speed control to torque control is performed gradually after the shifting is complete, thereby reducing torque impact while maintaining fast response.
Solution Approach 2:
The system applies beforehand cushioning by maintaining rotational speed control during the transition period. This prevents abrupt torque changes by cushioning the transition with continued speed control, thereby reducing impact while allowing quick overall response.
3Stability of the object's composition
If the rotational speed of the electric motor is controlled to match the clutch disk speed, then the shifting smoothness is improved, but the control complexity increases during the transition from speed control to torque control
Solution Approach 1:
The system uses feedback from the shifting state detection to determine when to switch from rotational speed control to torque control. By detecting whether the transmission is in a driving power transmission state or a driving power cut-off state, the control system automatically adjusts the control mode, thereby maintaining shifting smoothness while managing complexity through automated feedback-based decision making.
Data Source
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AI summary
An electric vehicle comprises a motor controller for controlling the electric motor in such a manner that the motor controller executes a control routine to perform torque control of the electric motor when the shifting state detecting device detects that the driving power transmission path is in the driving power transmission state, and executes a control routine to perform rotational speed control of the electric motor, when the shifting state detecting device detects that the driving power transmission path is in the driving power cut-off state; wherein in the rotational speed control, the rotational speed of the electric motor is controlled such that an angular velocity of an upstream rotary member in a shifting location of the driving power transmission path estimated by the estimating device gets close to an angular velocity of a downstream rotary member in the shifting location; wherein when the driving power transmission path is shifted from the driving power cut-off state to the driving power transmission state, the motor controller switches the rotational speed control to the torque control after performing predetermined transit control; and wherein the motor controller controls the electric motor such that a change rate of the torque output from the electric motor which occurs until the torque output from the electric motor reaches target torque demanded by a rider is made less in the transit control than in the torque control.