EV Torque Recovery Control on Slippery Roads With ABS Feedback
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Solution Overview
Problem
The safety and driving experience of electric vehicles on slippery roads are compromised due to repeated activation and inactivation of the anti-lock braking system (ABS) caused by energy recovery during coasting, leading to vehicle wheel locking.
Innovation Solution
Implementing a torque control method that presets a torque-lower-limit-value to prevent wheel locking, adjusting this value based on the anti-lock braking system's activation, and resetting it after a predetermined time to ensure smooth movement on slippery surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If energy recovery is performed during coasting process, then kinetic energy is converted into electric energy to be stored, but vehicle wheel may be locked due to low road adhesion coefficient
Solution Approach 1:
The patent dynamically adjusts the torque lower limit parameter based on vehicle operating conditions. When ABS activation is detected, the torque lower limit is modified from a first value (enabling energy recovery) to a second value (preventing wheel locking), thereby resolving the contradiction between energy recovery and vehicle safety on slippery road surfaces
Solution Approach 2:
The system implements feedback control by monitoring ABS activation status and road adhesion conditions. When ABS is activated, the controller detects this feedback signal and accordingly adjusts the torque lower limit parameter to prevent wheel locking, while resetting to the original value when conditions improve to resume energy recovery
2Reliability
If torque lower limit is set to prevent wheel locking, then vehicle safety is improved, but energy recovery capability is reduced
Solution Approach 1:
The patent employs dynamic parameter adjustment where the torque lower limit is not fixed but changes based on real-time vehicle conditions. The parameter switches between first value (for energy recovery) and second value (for safety) based on ABS activation status, optimizing both energy recovery and safety performance across different operating scenarios
3Reliability
If ABS is activated repeatedly during coasting, then wheel locking is prevented, but driving experience is seriously affected
Solution Approach 1:
The system takes preliminary action by proactively adjusting the torque lower limit parameter when ABS activation is detected. Instead of allowing repeated wheel locking and ABS activation cycles, the controller preemptively modifies the torque parameter to maintain stable wheel rotation, thereby preventing further ABS activations and ensuring smooth driving experience
Data Source
AI summary
A method for torque control of an electric vehicle on a slippery road surface and a terminal device are provided. The method includes: presetting a torque-lower-limit-value; setting, when an anti-lock braking system of the electric vehicle is activated, the torque-lower-limit-value as a second numerical value to reduce an absolute value of a reverse torque exerted on the vehicle wheel due to the energy recovery, and the vehicle wheel enters an anti-lock state; maintaining the anti-lock state of the vehicle wheel for a preset first time period; comparing the currently requested torque value with a preset third numerical value after the first time period is passed; and resetting the torque-lower-limit-value to the first numerical value to enable the vehicle wheel to exit the anti-lock state, if the currently requested torque value is greater than the third numerical value.