EV Torque Control Reducing Drive-Shaft Dead-Zone
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric vehicle control methods face delays in response during gear meshing due to gear backlash, particularly during slow acceleration or deceleration, leading to prolonged dead-zone periods and delayed torque rise, which affects the vehicle's drive-shaft torque response.
Innovation Solution
A control method for electric vehicles that calculates a final torque command value by considering the drive-shaft torsional angular velocity and using a vehicle model to estimate the dead-zone period, allowing separate feedback gains for the dead-zone and non-dead-zone periods to quicken the drive-shaft torque response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the drive motor torque is increased at the timing when the gears are meshed again, then the shock caused when the gears are meshed is restrained, but the timing when the torque rises delays due to the delay of the timing when the gears are meshed, which causes a delay in a response of the drive-shaft torque to a drive motor torque command
Solution Approach 1:
The control device predicts the timing of gear meshing in advance using a vehicle model that estimates the dead-zone period based on motor torque command values and gear backlash characteristics. By preparing the torque increase action before the actual gear meshing occurs, the system eliminates the delay that would otherwise cause delayed torque response, while still restraining shock through coordinated torque application at the predicted meshing moment
2Ease of operation
If the vehicle slowly accelerates from a coast or deceleration, then the increase slope of the torque command value of the motor becomes small, but the timing when the gears are meshed again delays and the dead-zone period becomes long
Solution Approach 1:
The vehicle model predicts the duration of the dead-zone period in advance based on the current motor torque command value and gear backlash characteristics. By identifying prolonged dead-zone periods before they fully develop, the system can prepare appropriate torque control actions ahead of time, ensuring that torque is applied effectively when gears mesh regardless of how long the dead-zone period becomes during slow acceleration
Solution Approach 2:
The control device dynamically adjusts the torque command value based on the predicted dead-zone period duration. When a prolonged dead-zone is anticipated, the system modifies the torque application strategy to ensure optimal response upon gear meshing, transforming the static torque control into a dynamic adaptation that responds to varying acceleration conditions and dead-zone durations
Data Source
AI summary
A control method for an electric vehicle includes controlling a torque of a motor based on a final torque command value by calculating the final torque command value such that a vibration damping control to reduce vibrations of a driving force transmission system of a vehicle is performed on a target torque command value set based on vehicle information, calculating the final torque command value based on the target torque command value and a value obtained by multiplying a drive-shaft torsional angular velocity by a feedback gain, estimating, by use of a vehicle model that models the driving force transmission system, a dead-zone period during which a motor torque output from the motor is not transmitted to a drive-shaft torque of the vehicle, and determining whether or not the vehicle is just before stop of the vehicle.