Regenerative Braking Torque Control for Engine Stall Prevention
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Solution Overview
Problem
Existing vehicle powertrain systems face challenges in effectively determining and managing regenerative braking torque capacity, particularly in balancing short-term and long-term axle torque capacities and preventing engine stalling during regenerative braking, which affects the efficiency and smooth operation of vehicles.
Innovation Solution
A powertrain system that includes an internal combustion engine and an electric machine, where the electric machine is rotatably coupled to the crankshaft, and a method for controlling the electric machine to determine preferred regenerative braking capacity based on short-term axle torque capacity, long-term axle torque capacity, engine stall regenerative braking capacity, and operator braking requests, allowing for controlled torque output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking torque is increased to improve energy recovery, then energy efficiency is improved, but engine stalling risk increases
Solution Approach 1:
The control system performs preliminary determination of engine stall regenerative braking capacity before actual regenerative braking occurs. By calculating the maximum torque the engine can withstand without stalling and comparing it with the requested regenerative braking torque, the system proactively adjusts the torque to prevent stalling before it happens, thus allowing higher energy recovery while maintaining engine reliability.
Solution Approach 2:
The system continuously monitors engine operating conditions and adjusts regenerative braking torque based on real-time feedback. The controller compares the requested regenerative braking torque with the determined engine stall capacity and modifies the actual torque applied to the engine, creating a closed-loop control system that maximizes energy recovery while preventing engine stalling.
2Power
If short-term axle torque capacity is maximized for immediate braking performance, then braking effectiveness is improved, but long-term torque capacity management deteriorates
Solution Approach 1:
The system dynamically adjusts regenerative braking torque based on real-time determination of both short-term and long-term axle torque capacities. The controller continuously evaluates the requested torque against both time horizons and adapts the actual torque applied, allowing the system to optimize immediate braking performance while preserving long-term torque capacity for sustained operation.
Solution Approach 2:
The control system determines long-term axle torque capacity in advance and uses this information to guide short-term torque decisions. By having the long-term capacity threshold pre-established, the system can make rapid adjustments during braking events while ensuring that long-term capacity is not compromised, thus balancing immediate effectiveness with sustained management.
3Use of energy by moving object
If complex control algorithms are used to optimize regenerative braking capacity, then regenerative braking efficiency is improved, but control system complexity increases
Solution Approach 1:
The control system segments the regenerative braking control into distinct functional modules: determining short-term axle torque capacity, determining long-term axle torque capacity, determining engine stall regenerative braking capacity, and comparing these with requested torque. This modular segmentation simplifies the overall control architecture while maintaining comprehensive optimization of regenerative braking efficiency.
Solution Approach 2:
The system performs preliminary determinations of various torque capacities (short-term, long-term, engine stall) before final torque application decisions. By pre-calculating these capacity thresholds and storing them for comparison, the control algorithm becomes more efficient and less computationally intensive during actual braking events, reducing real-time processing complexity while maintaining optimization effectiveness.
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 solution enables efficient management of regenerative braking torque, improving vehicle efficiency and preventing engine stalling by optimizing torque transfer and regenerative braking capacity, enhancing the overall performance and smooth operation of the powertrain system.
Implementation Method 1
electric motor/generators that are supplied electric power from high-voltage energy storage systems. Powertrain systems may employ regenerative control systems to recover electric power for charging the high-voltage energy storage system
Data Source
AI summary
A powertrain system including an internal combustion engine, a transmission and an electric machine is described, and includes the electric machine rotatably coupled to a crankshaft of the internal combustion engine. The transmission is coupled to a driveline to transfer tractive torque and braking torque thereto. A method for controlling the electric machine includes determining a short-term axle torque capacity, a long-term axle torque capacity and a maximum regenerative braking stall torque capacity, and determining an operator request for braking. A preferred regenerative braking capacity is determined based upon the short-term axle torque capacity, the long-term regenerative braking capacity, the engine stall regenerative braking capacity and the operator request for braking. Torque output from the electric machine is controlled based upon the preferred regenerative braking capacity.