Hybrid Vehicle Regenerative Braking Torque Segmentation
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Solution Overview
Problem
During antilock braking events in hybrid electric vehicles, regenerative braking is typically disabled to avoid destabilization, resulting in inefficient energy recovery and increased wear on friction brakes due to powertrain oscillations.
Innovation Solution
A controller filters the requested antilock wheel brake torque into different frequency components and commands the motor to provide regenerative brake torque for the lower frequency component, while the friction brake handles the higher frequency component, with adjustments based on wheel slip, battery state, and motor limits to ensure stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative braking is enabled during antilock braking events, then energy recovery efficiency is improved, but vehicle stability deteriorates due to powertrain oscillations
Solution Approach 1:
The braking torque is segmented into different frequency components using spectral analysis. The controller separates the oscillatory component (which causes powertrain oscillations) from the steady-state component, allowing regenerative braking to handle only the steady portion while friction brakes manage the oscillatory portion, thus maintaining stability while recovering energy.
Solution Approach 2:
The controller dynamically adjusts the regenerative braking torque parameter based on the spectral content of the requested braking torque. By monitoring frequency components and adjusting the regenerative torque contribution in real-time, the system optimizes energy recovery while preventing destabilizing oscillations.
2Reliability
If regenerative braking is disabled during antilock braking events, then vehicle stability is maintained, but friction brake wear increases
Solution Approach 1:
The braking system is segmented into two parallel paths: regenerative braking handles the steady-state torque component while friction brakes handle the oscillatory component. This segmentation allows friction brakes to remain engaged during ABS events (maintaining stability) while their workload is reduced, extending their service life.
Solution Approach 2:
The system merges regenerative and friction braking systems to work cooperatively during ABS events. By combining the advantages of both systems (regenerative energy recovery and friction brake stability control), the system achieves both stability maintenance and reduced friction brake wear.
3Loss of energy
If regenerative braking is enabled during antilock braking events, then energy recovery is improved, but control complexity increases due to frequency filtering requirements
Solution Approach 1:
The control system replaces complex mechanical vibration isolation mechanisms with electronic signal processing. By using spectral analysis and frequency filtering algorithms in the controller, the system achieves oscillation separation without adding mechanical complexity, managing control complexity through software-based solutions.
4Reliability
If friction brake torque is increased during antilock braking events, then vehicle stability is maintained, but energy recovery efficiency decreases
Solution Approach 1:
The friction brake torque is segmented to include only the oscillatory frequency component, while the steady-state component is assigned to regenerative braking. This segmentation reduces the overall torque burden on friction brakes during ABS events, allowing energy recovery to handle more of the braking load and improve efficiency.
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 regenerative braking during antilock events, recovering more kinematic energy as electrical energy and reducing friction brake wear, while maintaining vehicle stability and reducing stopping distance.
Implementation Method 1
The motor is coupled to the wheel and configured to provide regenerative brake torque
Implementation Method 2
The friction brake is coupled to the wheel and configured to provide friction brake torque
Data Source
AI summary
A hybrid electric vehicle includes at least one wheel, a friction brake, a motor, and at least one controller. The friction brake is coupled to the wheel and configured to provide friction brake torque, and the motor is coupled to the wheel and configured to provide regenerative brake torque. The controller is configured to command the motor to provide a regenerative brake torque to satisfy a low frequency torque component or a high frequency torque component of a required antilock wheel brake torque during an antilock braking event.