Electric Traction Motor Torque Control for Vehicle Stability
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Solution Overview
Problem
Existing methods for operating motor vehicles with electric traction machines struggle to maintain stable driving behavior during braking and acceleration, particularly in achieving strong deceleration or acceleration while ensuring driving stability.
Innovation Solution
A method that involves setting a speed setpoint range on a control unit to regulate torque control, adjusting actual torque to match the setpoint torque when within the range, and prioritizing speed control to bring the actual speed within the setpoint range when it is outside, using electric traction machines to apply torque effectively, and dividing braking torque between service brakes and traction machines for optimal braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If torque control is performed to adjust actual torque to target torque, then acceleration performance is improved, but driving stability deteriorates when wheel speed is outside optimal range
Solution Approach 1:
The control method dynamically switches between torque control mode and speed control mode based on the wheel's actual speed relative to the target speed range. When speed is within range, torque control provides strong acceleration; when speed is outside range, speed control ensures stability by preventing further deviation. This dynamic adaptation resolves the contradiction between acceleration performance and driving stability.
2Force
If service brakes are used for deceleration, then braking force is provided, but braking distance increases and braking performance is insufficient
Solution Approach 1:
The invention merges the braking functions of service brakes and electric traction motors into a coordinated braking system. The service brakes provide baseline braking force, while the electric traction motor contributes additional braking torque through regenerative braking or dynamic braking. This combination achieves stronger overall braking force and shorter braking distance compared to service brakes alone.
3Productivity
If electric traction motor provides braking torque, then braking performance is improved, but wheel speed control precision deteriorates without speed range limitation
Solution Approach 1:
The control system continuously monitors the wheel's actual speed and compares it with the target speed range, using this feedback to determine the appropriate control mode. When the actual speed deviates from the target range, the system switches to speed control mode to correct the deviation, ensuring precise wheel speed control while maintaining improved braking performance through electric torque application.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method improves driving stability and acceleration by ensuring the motor vehicle operates within optimal torque and speed conditions, allowing for rapid and effective deceleration and acceleration, and maintaining torque distribution across multiple wheels for enhanced control.
Implementation Method 1
drive unit (8, 9, 10, 11) comprising at least one electric traction machine (8, 9, 10, 11)
Implementation Method 2
service brake and the electric machine jointly providing the braking force
Data Source
AI summary
The invention relates to a method for operating a motor vehicle (1), which has a drive device comprising at least one electrical traction machine (8, 9, 10, 11), wherein, in order to provide a torque at a wheel (3, 4, 6, 7) of the motor vehicle (1), a target torque is set at a control unit of the traction machine (8, 9, 10, 11) and torque control for setting an actual torque produced by the traction machine (8, 9, 10, 11) is carried out by means of the control unit. According to the invention, a rotational speed target range is additionally set at the control unit and, if the actual rotational speed of the wheel (3, 4, 6, 7) is in the rotational speed target range, the actual torque is controlled to the target torque in the course of the torque control and, if the actual rotational speed is outside of the rotational speed target range, the torque control is carried out in such a way that the actual rotational speed is changed toward the rotational speed target range. The invention also relates to a motor vehicle (1).