Electric Vehicle Torque Control System for Wheel Slip

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Solution Overview

Problem

Current traction control systems for hybrid and all-electric vehicles are inadequate due to differences in vehicle weight, weight distribution, and drive train torque and power capabilities compared to conventional vehicles, necessitating a system designed specifically for these alternative fuel vehicles.

Innovation Solution

A torque and traction control system for all-wheel drive electric vehicles that includes motor speed sensors, temperature sensors, steering sensors, brake sensors, and accelerator sensors, utilizing a second-stage feedback control system and transient torque boost feedforward control circuit to optimize torque distribution across wheels, accounting for wheel slip and other operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional traction control systems are used in electric vehicles, then the systems can detect wheel spin and redirect torque, but the systems are unsatisfactory due to differences in vehicle weight, weight distribution, and drive train torque capabilities

Engineering Contradiction:
Improveadaptability to electric vehicle characteristicsVSAvoidtraction control effectiveness
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The control system is specifically designed with parameters optimized for electric vehicle characteristics including weight, weight distribution, and drive train torque capabilities. The system adjusts control parameters such as torque redistribution ratios and wheel spin detection thresholds to match EV-specific operating conditions, making the system adaptable and effective for electric vehicles rather than using generic conventional control parameters

Inventive Principle:
Principle #35Parameter changes

2Force

If torque is increased to wheels with traction to improve safety, then traction is improved, but wheel spin and slippage occur under certain conditions

Engineering Contradiction:
Improvetraction forceVSAvoidwheel spin
Core Design Contradiction:
ForceVSObject-generated harmful factors

Solution Approach 1:

The system continuously monitors wheel speed sensors to detect wheel spin conditions and uses this feedback to dynamically adjust torque distribution. When wheel spin is detected on a driven wheel, the system automatically redirects torque away from the spinning wheel to wheels with better traction, creating a closed-loop control system that prevents harmful wheel spin while maintaining optimal traction force

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system takes preliminary action by detecting early signs of wheel spin through wheel speed sensors and preemptively redirecting torque before significant slippage occurs. The control system anticipates potential wheel spin conditions and adjusts torque distribution in advance to prevent the harmful effect from developing fully

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If a sophisticated electronic control system is implemented to optimize torque distribution, then traction control improves, but system complexity increases

Engineering Contradiction:
Improvetraction control effectivenessVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The electronic control system performs multiple functions including wheel spin detection, torque redistribution control, and various driving mode management (snow mode, sport mode, normal mode). By consolidating these functions into a single multi-functional control unit, the system achieves sophisticated traction control effectiveness while avoiding the complexity of having separate dedicated systems for each function

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2223821B1Control system for an electric vehicle
Publication Date: 2020.06.17 TESLA INC
  • EP2223821B1 patent drawingFigure 1~3
  • EP2223821B1 patent drawingFigure 4
  • EP2223821B1 patent drawingFigure 5

AI summary

A method and apparatus for optimizing the torque applied to the primary and assist drive systems of an all-electric vehicle is provided, the torque adjustments taking into account wheel slip as well as other vehicular operating conditions.