Driven Axle Slip Control for Electric Vehicle Traction
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Solution Overview
Problem
Existing vehicle systems lack effective control over wheel slip during various driving conditions, particularly with electric drive units, which can lead to uncontrollable drifting and reduced traction.
Innovation Solution
A method for controlling a driven axle of a motor vehicle by establishing actual and target wheel speeds, determining slip, and adjusting drive torque through a control device to maintain a limit torque, preventing excessive slip and ensuring controlled wheel movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drive torque is increased to improve acceleration performance, then the productivity is improved, but the wheel slip increases causing loss of traction and controllability
Solution Approach 1:
The control device continuously monitors the actual speed of the wheel and vehicle, calculates the slip, and adjusts the drive torque accordingly. When slip exceeds a threshold, the control device reduces drive torque to maintain traction, creating a closed-loop feedback system that balances acceleration performance with traction control.
Solution Approach 2:
The system dynamically adjusts the drive torque based on real-time slip conditions. The control device modifies the torque output of the electric drive unit according to the calculated slip, allowing the system to adapt its characteristics to maintain optimal traction while preserving acceleration capability when conditions permit.
2Reliability
If the drive torque is limited to prevent excessive slip, then the reliability of traction control is improved, but the acceleration performance deteriorates
Solution Approach 1:
The control device applies partial torque limitation only when and where needed. Instead of continuously limiting torque, the system monitors slip and applies torque reduction only when slip exceeds the threshold, allowing full acceleration performance to be utilized when traction conditions are adequate while providing targeted intervention only when necessary.
3Measurement precision
If the control system continuously monitors wheel and vehicle speeds to calculate slip, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The control device performs multiple functions using the same sensor inputs. The wheel speed sensor and vehicle speed data are utilized not only for slip calculation but also for traction control, stability control, and other vehicle dynamics functions, making the control system multi-functional and reducing the need for separate dedicated systems.
Data Source
AI summary
Controlling an actual slip of at least one driven axle of a motor vehicle with at least one axle having at least one wheel and a one drive unit for providing a drive torque for the axle and for the wheel can be carried out by a control device for controlling the drive unit. The control device can be configured for establishing a first actual speed of the motor vehicle; establishing a second actual speed of the at least one wheel; calculating a target speed of the at least one wheel for the established first actual speed taking into account parameters; determining an actual slip of the at least one wheel with respect to a substrate on which the motor vehicle is being moved; when the actual slip exceeds a defined first limit slip, generating a limit torque by which the drive torque produced by the drive unit is adjusted.