Regenerative Braking Torque Control via Wheel Slip Feedback
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Solution Overview
Problem
Current hybrid and electric vehicles face inefficiencies in regenerative braking during anti-lock braking events, as traditional systems deactivate regenerative braking to prevent wheel locking, leading to reduced energy recovery and prolonged braking distances.
Innovation Solution
A vehicle control system that adjusts regenerative braking torque based on the difference between desired and actual wheel slip ratios, allowing simultaneous regenerative and anti-lock braking by coordinating electric machines and friction brakes to maintain optimal wheel slip and energy recovery during anti-lock braking events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative braking is deactivated during anti-lock braking events to prevent wheel locking, then wheel stability is improved, but energy recovery is reduced
Solution Approach 1:
The system dynamically adjusts the regenerative braking torque based on real-time wheel slip ratio feedback. The controller continuously monitors the actual wheel slip ratio and modulates the electric machine torque to maintain optimal slip conditions, enabling regenerative braking to remain active during anti-lock braking events while preventing wheel lockup.
Solution Approach 2:
The control system implements a feedback mechanism where the actual wheel slip ratio is measured and compared against a desired slip ratio threshold. Based on this feedback, the controller adjusts the regenerative braking torque in real-time, allowing the system to maintain both wheel stability and energy recovery simultaneously.
2Reliability
If regenerative braking is deactivated during anti-lock braking events, then wheel lockup is prevented, but braking distance is prolonged
Solution Approach 1:
The system employs dynamic torque modulation where the regenerative braking torque is continuously adjusted based on wheel slip ratio feedback. This allows the electric machine to provide optimal braking force that prevents wheel lockup while maximizing deceleration efficiency, thereby reducing braking distance compared to complete deactivation.
Solution Approach 2:
The control system changes the operating parameters of the regenerative braking system by adjusting torque levels based on slip ratio conditions. By maintaining regenerative braking within optimal parameter ranges during anti-lock events, the system achieves both lockup prevention and reduced braking distance.
3Loss of energy
If regenerative braking torque is increased during anti-lock braking events, then energy recovery is improved, but wheel slip control becomes difficult
Solution Approach 1:
The system uses real-time feedback from wheel slip ratio sensors to continuously adjust regenerative braking torque. This closed-loop control ensures that energy recovery is maximized while maintaining precise wheel slip control, as the controller can immediately respond to any slip condition changes by modulating the electric machine torque.
Solution Approach 2:
The control system dynamically adjusts the regenerative braking torque levels based on current wheel slip conditions rather than using fixed torque values. This dynamic adjustment allows the system to optimize energy recovery at each moment while preventing wheel lockup, making high energy recovery compatible with easy slip control.
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 enables efficient energy recovery during anti-lock braking events, reducing braking distances and improving vehicle stability while maintaining regenerative braking functionality, thus enhancing overall vehicle performance and fuel efficiency.
Implementation Method 1
During regenerative braking, an electric machine may operate as a generator to convert the kinetic energy of the vehicle into electrical energy which is in turn used to charge a battery
Implementation Method 2
The friction brakes are configured to apply torque to wheels of the vehicle to decelerate the vehicle
Data Source
AI summary
A vehicle includes an electric machine, friction brakes, and a controller. The electric machine is configured to recharge a battery during regenerative braking. The friction brakes are configured to apply torque to wheels of the vehicle to decelerate the vehicle. The controller is programmed to, responsive to an anti-lock braking event, adjust a regenerative braking torque of the electric machine based on a difference between a desired wheel slip ratio and an actual wheel slip ratio.