EV Drive Torque Mode Switching to Minimize Backlash and NVH
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Solution Overview
Problem
Existing torque control methods in electric vehicle drive systems struggle to avoid backlash bands, leading to drivability issues, excessive response times, and NVH problems, while current backlash correction methods fail to prevent vibration occurrence.
Innovation Solution
A torque control method that determines a torque control mode based on the vehicle's driving state and transitions between modes, limiting torque slope to avoid backlash bands by dividing torque operations between front- and rear-wheel motors, using reverse and co-directional distribution strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If torque change rate is set large to improve acceleration responsiveness, then vehicle responsiveness is improved, but NVH issues occur due to drive shaft torsion, gear backlash striking, and torque shock
Solution Approach 1:
The controller predicts future torque requirements and proactively adjusts torque commands before backlash occurs. By using a disturbance observer to estimate drive shaft speed and comparing it with a model speed, the system anticipates backlash conditions and pre-adjusts torque to avoid gear backlash striking and torque shock, thereby reducing NVH while maintaining responsive acceleration.
Solution Approach 2:
The system implements active feedback control by continuously monitoring drive shaft speed through a disturbance observer and comparing it with model speed. When backlash is detected or predicted, the controller provides feedback correction to the torque command, dynamically adjusting torque change rate to prevent NVH issues while preserving acceleration responsiveness.
2Object-generated harmful factors
If torque change rate is set small to reduce NVH, then vibration is reduced, but vehicle responsiveness deteriorates and acceleration time increases
Solution Approach 1:
The controller predicts future torque requirements and proactively adjusts torque commands before backlash occurs. By using a disturbance observer to estimate drive shaft speed and comparing it with a model speed, the system anticipates backlash conditions and pre-adjusts torque to avoid gear backlash striking and torque shock, thereby reducing NVH while maintaining responsive acceleration.
Solution Approach 2:
The system implements active feedback control by continuously monitoring drive shaft speed through a disturbance observer and comparing it with model speed. When backlash is detected or predicted, the controller provides feedback correction to the torque command, dynamically adjusting torque change rate to prevent NVH issues while preserving acceleration responsiveness.
3Object-generated harmful factors
If active feedback torque correction control is applied to suppress vibration after backlash occurs, then NVH is reduced, but vehicle responsiveness deteriorates due to hardware characteristics
Solution Approach 1:
The controller predicts future torque requirements and proactively adjusts torque commands before backlash occurs. By using a disturbance observer to estimate drive shaft speed and comparing it with a model speed, the system anticipates backlash conditions and pre-adjusts torque to avoid gear backlash striking and torque shock, thereby reducing NVH while maintaining responsive acceleration.
Solution Approach 2:
The system implements active feedback control by continuously monitoring drive shaft speed through a disturbance observer and comparing it with model speed. When backlash is detected or predicted, the controller provides feedback correction to the torque command, dynamically adjusting torque change rate to prevent NVH issues while preserving acceleration responsiveness.
Data Source
AI summary
A torque control method in a drive system of an electric vehicle includes determining, by a controller, a torque control mode corresponding to a current vehicle driving state among a plurality of preset torque control modes; and transitioning, by the controller, from a current torque control mode to the determined torque control mode, in which the transitioning to the determined torque control mode comprises performing, by the controller, limitation to a torque slope using a torque command at an immediately previous control cycle with respect to a front-wheel torque command that is a command for a front-wheel motor and a rear-wheel torque command that is a command for a rear-wheel motor, in a transient section where transition between torque control modes occurs.