Electric Vehicle Torque Control Preventing Wheel Slip
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Solution Overview
Problem
Conventional control systems for electric vehicles fail to effectively suppress simultaneous slip of front and rear wheels, especially when driver operation is excessive on varying road surfaces.
Innovation Solution
A control apparatus for electric vehicles that includes a front electric motor and a rear electric motor, with a control system that calculates and adjusts torque command values to ensure a lower achievement rate for one motor compared to the other, thereby preventing simultaneous slip by compensating for torque reductions and managing torque distribution based on road conditions and vehicle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque distribution is adjusted to suppress wheel slip on upward slopes, then starting performance is improved, but simultaneous slip of front and rear wheels cannot be prevented when driver operation is excessive
Solution Approach 1:
The control system dynamically adjusts the achievement rate of torque command values based on driving conditions and driver operation intensity. When excessive driver operation is detected, the system reduces the achievement rate to prevent simultaneous wheel slip, while maintaining high achievement rates under normal conditions for optimal starting performance.
Solution Approach 2:
The system changes the parameter of achievement rate (temporal delay characteristic) based on detected driving conditions. By varying this parameter according to road gradient, vehicle speed, and driver operation intensity, the system adapts torque response characteristics to prevent simultaneous slip while maintaining starting capability.
2Speed
If torque command values are increased to improve acceleration performance, then vehicle responsiveness is improved, but the risk of simultaneous wheel slip increases
Solution Approach 1:
The control system preliminarily adjusts the achievement rate of torque command values based on predicted wheel slip risk. Before simultaneous slip can occur, the system has already reduced the achievement rate in response to detected conditions, preventing the harmful effect while maintaining acceleration performance.
Solution Approach 2:
The system continuously monitors wheel speed, vehicle acceleration, and torque command achievement rates, using this feedback to dynamically adjust torque distribution. When feedback indicates approaching slip conditions, the system reduces achievement rates to prevent simultaneous slip while maintaining overall acceleration performance.
3Reliability
If the achievement rate of torque command is reduced to prevent simultaneous slip, then wheel slip suppression is improved, but torque response speed may be affected
Solution Approach 1:
The system applies different achievement rates to front and rear motors based on local conditions. By selectively reducing the achievement rate only when and where simultaneous slip risk exists, the system maintains high torque response speed in other conditions while preventing simultaneous slip when needed.
Data Source
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AI summary
Provided is a control apparatus for an electric vehicle, which is capable of suppressing simultaneous slip of front and rear wheels. The control apparatus for an electric vehicle includes a control portion configured to control a front electric motor and a rear electric motor so that an achievement rate of a torque command with respect to a target torque in one motor of the front and rear electric motors is lower than the achievement rate in the other motor of the front and rear electric motors.