Regenerative Braking Torque Derating for Low-Traction Roads

Solution Overview

Problem

Existing hybrid and electric powertrain systems experience frequent traction control events due to automatic regenerative braking on slick roads, leading to inefficient energy capture and potential safety issues, as the braking torque application is not adapted to current road conditions.

Innovation Solution

A method and system that utilizes a vehicle's onboard ABS device to detect traction loss, adjusting regenerative braking torque limits based on ambient and GPS information, incrementally derating torque during traction control events and gradually returning to normal operation after a verification period, with adjustments influenced by temperature and weather conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If regenerative braking is automatically applied when the accelerator pedal is released, then energy capture efficiency is improved, but traction control events increase on slick roads

Engineering Contradiction:

Improveenergy capture efficiencyVSAvoidtraction control stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system dynamically adjusts the regenerative braking torque limit based on detected road conditions. When slick road conditions are detected through traction control events, the system reduces the regenerative braking torque limit to prevent excessive wheel slip. This dynamic adaptation allows the system to maintain high energy capture efficiency on dry roads while ensuring traction control stability on slick roads.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the traction control system to detect when traction control events occur. This feedback mechanism allows the system to identify slick road conditions and automatically adjust the regenerative braking torque limit accordingly. The feedback loop ensures that energy capture is optimized when conditions permit while preventing traction loss when conditions deteriorate.

Inventive Principle:

Principle #23Feedback

2Reliability

If regenerative braking torque limit is reduced to prevent traction control events, then traction stability is improved, but energy capture efficiency deteriorates

Engineering Contradiction:

Improvetraction control stabilityVSAvoidenergy capture efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the regenerative braking torque limit based on detected road conditions. When slick road conditions are detected through traction control events, the system reduces the regenerative braking torque limit to prevent excessive wheel slip. This dynamic adaptation allows the system to maintain high energy capture efficiency on dry roads while ensuring traction control stability on slick roads.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of regenerative braking torque limit based on road conditions. By detecting traction control events, the system identifies when to reduce the torque limit parameter to maintain traction stability. This parameter adjustment ensures that energy capture efficiency is maximized when conditions allow while preventing traction loss when conditions deteriorate.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If a dashboard switch is provided to turn off regenerative braking, then driver control is improved, but energy capture is disabled long-term even in favorable conditions

Engineering Contradiction:

Improvedriver controlVSAvoidenergy capture efficiency

Core Design Contradiction:

Ease of operationVSUse of energy by moving object

Solution Approach 1:

The system provides self-service by automatically detecting slick road conditions through traction control events and adjusting the regenerative braking torque limit without requiring driver intervention. This eliminates the need for a dashboard switch while maintaining driver control over the vehicle. The system serves itself by using its own traction control data to make intelligent decisions about regenerative braking application.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses feedback from the traction control system to detect when traction control events occur. This feedback mechanism allows the system to identify slick road conditions and automatically adjust the regenerative braking torque limit accordingly. The feedback loop ensures that energy capture is optimized when conditions permit while preventing traction loss when conditions deteriorate, eliminating the need for manual driver control switches.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3992040B1Method and system for performing regenerative braking with feedback from brake-traction control system

Publication Date: 2025.09.10 CUMMINS INC

Figure 1A~1B
Figure 2
Figure 3A~3B

AI summary

Methods and systems for operating a vehicle on a reduced traction surface are disclosed. A controller of the vehicle obtains at least one of: ambient information or GPS information, determines a derate increment size based on the ambient or GPS information, imposes a sustained derate by applying a torque limit on a braking torque of the vehicle based on the derate increment size in response to detecting a traction control event. The controller also determines a verification period and a derate reduction period based on the ambient or GPS information to reduce the sustained derate in response to detecting a lack of traction control event during the verification period at a rate determined by the derate reduction period.