Regenerative Braking Torque Control to Avoid ABS Intervention
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Solution Overview
Problem
Electric vehicles equipped with anti-lock brake systems (ABS) face challenges in maximizing energy recovery through regenerative braking due to ABS operations interfering with the regenerative braking process, requiring additional sensors for vehicle body speed estimation and resulting in insufficient energy recovery.
Innovation Solution
An apparatus and method that utilize a disturbance extractor and torque compensator to adjust regenerative braking torque based on a behavior model of the electric vehicle, preventing ABS operation and maximizing energy recovery by calculating compensation torque to offset disturbances and prevent hysteresis phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is applied to maximize energy recovery, then energy recovery rate is improved, but ABS enters operating range causing wheel lock and interrupting regenerative braking
Solution Approach 1:
The controller proactively adjusts regenerative braking torque before ABS activation occurs by monitoring wheel speed differences and predicting ABS operating range entry. When the difference between vehicle body speed and wheel speed approaches the ABS threshold, the controller reduces regenerative braking torque in advance, preventing ABS activation and maintaining continuous energy recovery.
Solution Approach 2:
The system continuously monitors wheel speed, vehicle body speed, and their difference to provide real-time feedback to the controller. This feedback loop enables dynamic adjustment of regenerative braking torque based on current operating conditions, ensuring energy recovery is maximized while keeping wheel speed difference within safe limits that prevent ABS activation.
2Use of energy by moving object
If conventional target slip control is used to improve energy recovery, then regenerative braking efficiency is improved, but additional sensors are required to estimate vehicle body speed
Solution Approach 1:
The system uses existing sensors (wheel speed sensor and motor controller data) to self-determine vehicle body speed through calculation rather than requiring additional dedicated sensors. The controller leverages available data from the regenerative braking system itself to compute vehicle speed, eliminating the need for separate sensing hardware while maintaining control accuracy.
Solution Approach 2:
The controller acts as an intermediary that processes information from existing sensors and existing vehicle parameters to derive vehicle body speed indirectly. Rather than directly measuring vehicle body speed with a separate sensor, the system uses the controller's computational capabilities to calculate it from motor current, wheel speed, and vehicle parameters already present in the system.
3Use of energy by moving object
If regenerative braking torque is increased to maximize energy recovery, then energy recovery rate is improved, but wheel speed difference increases causing ABS activation
Solution Approach 1:
The controller dynamically adjusts regenerative braking torque based on real-time wheel speed difference conditions. When wheel speed difference is small, higher regenerative braking torque is applied to maximize energy recovery. When wheel speed difference approaches the ABS threshold, the controller dynamically reduces torque to maintain safety margins, creating an adaptive balance between energy recovery and ABS prevention.
Data Source
AI summary
An apparatus and method control regenerative braking torque of an electric vehicle on which an anti-lock brake system (ABS) is mounted. The apparatus and method can compensate the regenerative braking torque of the driving motor based on the behavior model of the electric vehicle, such that the ABS is prevented from entering an operating range to the maximum limit to maximize the energy recovery rate through regenerative braking. The apparatus includes a disturbance extractor that extracts a disturbance in a specific frequency band from a difference between a behavior model and an actual behavior of the electric vehicle. The apparatus includes a torque compensator that compensates for the regenerative braking torque based on the disturbance extracted by the disturbance extractor.