Regenerative Braking Torque Control Under Wheel Load Changes
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Solution Overview
Problem
Hybrid and electric vehicles face limitations in regenerative braking capacity, particularly when fully loaded or towing a trailer, which reduces their driving range due to insufficient conversion of kinetic energy into electric charge.
Innovation Solution
A vehicle operating method that adjusts the torque of electric machines based on estimated coefficients of friction, normal load, vertical and longitudinal speed changes, and lateral slip, allowing for dynamic adjustment of regenerative braking torque to optimize energy capture and trailer braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking capacity is increased to capture more kinetic energy, then driving range is improved, but vehicle stability and wheel slip control deteriorate under loaded conditions
Solution Approach 1:
The system dynamically adjusts regenerative braking torque based on real-time wheel slip conditions, normal load, and friction coefficient estimates. The controller continuously modifies torque application to maintain optimal energy capture while preventing wheel lockup and slip, especially under varying load conditions.
Solution Approach 2:
The system uses feedback from wheel speed sensors, normal load measurements, and friction coefficient estimation to continuously adjust regenerative braking torque. This closed-loop control ensures that energy capture is maximized while maintaining wheel slip within acceptable limits.
2Use of energy by moving object
If regenerative braking torque is increased to improve energy conversion, then driving range extends, but trailer braking performance deteriorates when fully loaded
Solution Approach 1:
The system dynamically adjusts the distribution of braking torque between the vehicle and trailer based on real-time conditions including normal load, friction coefficient, and braking demand. This dynamic allocation ensures optimal energy capture from the vehicle while maintaining adequate braking performance for the trailer.
Solution Approach 2:
The system changes the braking torque parameter dynamically based on estimated friction coefficient, normal load, and braking conditions. By adjusting torque distribution as parameters change, the system optimizes both energy capture and trailer braking performance across varying operating conditions.
3Use of energy by moving object
If dynamic adjustment of regenerative braking torque is implemented to optimize energy capture, then driving range improves, but control system complexity increases
Solution Approach 1:
The system uses readily available sensor data from the vehicle's existing infrastructure (wheel speed sensors, load measurements) to autonomously adjust regenerative braking torque. The controller self-regulates based on pre-programmed logic that responds to real-time conditions, eliminating the need for additional complex control mechanisms.
Solution Approach 2:
The control system integrates multiple functions into a single controller that handles both vehicle stability control and energy optimization. By making the controller multi-functional, the system achieves complex control objectives without adding separate dedicated systems for each function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the conversion of kinetic energy into electric charge during regenerative braking, improving the vehicle's driving range, especially under loaded and towing conditions, by dynamically adjusting torque and trailer braking.
Implementation Method 1
electric machines may convert torque from the vehicle's wheels into electric charge
Data Source
AI summary
Methods and systems are provided for adjusting regenerative braking in response to normal loads applied to each of a vehicle's wheels coupled to an electric machine. In one example, a regenerative braking torque for a wheel may be adjusted in response to a normal load that is applied to the wheel as wheel load changes during vehicle braking.