Hybrid Vehicle Braking Torque Allocation via Anti-Lock Segmentation
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Solution Overview
Problem
Hybrid vehicles with larger inertia electric machines face challenges in regenerative braking, as they tend to increase the risk of wheel locking during braking, and existing systems struggle to effectively combine regenerative and friction braking to manage kinetic energy conversion efficiently.
Innovation Solution
The method involves adjusting the regeneration torque of the primary axle to a lower magnitude value based on low-pass filtered wheel regulation torques and activating anti-lock braking systems to decompose wheel torque into regenerative and friction braking components, ensuring that regenerative braking does not interfere with wheel speed regulation and reducing the risk of wheel locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the electric machine has a larger inertia to provide substantial torque for vehicle acceleration, then the vehicle acceleration performance is improved, but the risk of wheel locking during regenerative braking increases
Solution Approach 1:
The braking torque is segmented into two distinct components: regenerative braking torque (handled by the electric machine) and friction braking torque (handled by the friction brake system). This segmentation allows each subsystem to operate within its optimal range, with the friction brake providing immediate torque modulation to prevent wheel locking while the electric machine handles energy recovery.
Solution Approach 2:
The friction brake system acts as an intermediary between the driver's braking request and the regenerative braking system. When wheel locking is detected or anticipated, the friction brake applies torque to the wheels to prevent locking, while the control system coordinates between the friction brake and electric machine to maintain both safety and energy recovery efficiency.
2Loss of energy
If regenerative braking torque is increased to capture more kinetic energy, then energy storage efficiency is improved, but wheel speed control precision deteriorates
Solution Approach 1:
The system dynamically adjusts the distribution between regenerative braking torque and friction braking torque based on real-time wheel speed feedback. The control system continuously monitors wheel speed and modifies the torque allocation to maintain optimal regenerative braking effectiveness while preventing wheel locking and maintaining speed control precision.
Solution Approach 2:
The control system changes the parameter of braking torque distribution by adjusting the friction brake torque in response to wheel speed conditions. When wheel speed approaches locking thresholds, the friction brake torque is increased while regenerative braking torque is modulated, effectively changing the braking parameter mix to maintain both energy recovery and speed 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 enhances the storage of kinetic energy as electric energy while minimizing the risk of wheel locking, even with larger inertia electric machines, and compensates for unusual vehicle conditions by effectively managing regenerative and friction braking torques.
Implementation Method 1
Kinetic energy of a hybrid vehicle may be converted into electrical energy via an electric machine in the hybrid vehicle's driveline. In particular, vehicle wheel torque may be converted into electrical energy via the electric machine, which may be referred to as regenerative braking.
Implementation Method 2
The regenerative braking torque of a wheel may include lower brake regulation torque frequencies and the friction braking torque of the wheel may include higher regulation torque frequencies so that electric machine torque does not have to respond to the higher wheel regulation torque frequencies.
Data Source
AI summary
Methods and systems are provided for operating a hybrid vehicle during operating conditions where vehicle braking is requested. In one example, regenerative braking is allocated to vehicle axles responsive to wheel torques of respective vehicle axles in response to an anti-lock braking system being activated. Additionally, friction braking torque is allocated to vehicle axles responsive to the anti-lock braking system being activated.