Traction Motor Torque Limiting During Wheel Slip Events

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Solution Overview

Problem

In electric drive systems, wheel slip events cause rapid acceleration of wheels, leading to a rapid increase in electrical power consumption that can exceed the capability of the traction battery, potentially causing battery damage and activating intrusive battery protection features.

Innovation Solution

A control system that includes one or more electronic controllers configured to receive a torque request for the traction motor, determine the prevailing speed value and maximum allowable increase in speed of the traction motor, and set an electrical power consumption limit based on these parameters. The system then controls torque provision to prevent excessive power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If driving torque is reduced as soon as slip is detected in conventional traction control systems, then wheel slip is controlled, but the response time is not critical due to higher inertia in conventional engine and transmission systems

Engineering Contradiction:

Improvewheel slip controlVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The control system performs preliminary calculations of maximum allowable speed increase and power consumption limits before wheel slip occurs. By pre-determining these parameters based on prevailing speed values and latency periods, the system is prepared to respond immediately when slip is detected, eliminating the need for lengthy real-time calculations during the critical response phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts torque limits based on real-time operating conditions including prevailing speed values, latency periods, and calculated power consumption limits. The torque request is continuously modified according to the determined maximum allowable speed increase, creating a dynamic control response that adapts to changing vehicle states while maintaining rapid response capability.

Inventive Principle:

Principle #15Dynamics

2Speed

If driving torque is reduced immediately upon slip detection, then wheel acceleration is limited, but the decelerating power requirement is not high in conventional systems with higher inertia

Engineering Contradiction:

Improvewheel acceleration controlVSAvoiddecelerating power requirement

Core Design Contradiction:

SpeedVSPower

Solution Approach 1:

The system changes the parameter of torque limit based on calculated power consumption limits that account for the specific operating conditions. By determining maximum allowable speed increase as a function of prevailing speed value and latency period, the system dynamically adjusts the torque parameter to prevent excessive power consumption while maintaining effective wheel acceleration control during slip events.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If torque request is controlled based on prevailing speed value and maximum allowable speed increase, then electrical power consumption is limited to battery capability, but the control system complexity increases

Engineering Contradiction:

Improveelectrical power consumptionVSAvoidcontrol system complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors prevailing speed values, calculates maximum allowable speed increase based on latency period, and adjusts torque request accordingly. This closed-loop feedback mechanism ensures power consumption remains within battery capability while maintaining simple control logic through iterative adjustment of torque limits.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP4139155B1Control system and method for controlling electrical power consumption by traction motor caused by wheel slip

Publication Date: 2025.04.09 JAGUAR LAND ROVER LTD

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AI summary

Aspects of the present invention relate to a control system for controlling electrical power consumption from energy storage means by a traction motor of a vehicle caused by a wheel slip event, the control system comprising one or more electronic controllers, the one or more electronic controllers configured to: receive a torque request for an electric the traction motor of the vehicle; determine a current known prevailing speed value of an electric the traction motor of the vehicle; determine a maximum allowable increase in speed of the electric traction motor of the vehicle to occur during a latency period associated with the prevailing speed value of the current known speed of the electric traction motor of the vehicle; determine an electrical power consumption limit in dependence on the torque request, the current known prevailing speed value of the electric traction motor of the vehicle and the maximum allowable increase in speed of the electric traction motor; and control torque provision of the electric traction motor in dependence on the torque request and the electrical power consumption limit.