Dual-Axle BEV Torque Split Using Traction Torque Ranges
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Solution Overview
Problem
Existing battery electric vehicles (BEVs) face challenges in efficiently controlling torque split between propulsion units, which affects vehicle dynamics, traction, and overall efficiency.
Innovation Solution
A controller system that receives torque request and traction signals to determine a traction torque range for each propulsion unit, allowing for a proposed torque distribution that ensures no loss of traction, thereby generating appropriate torque control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If torque is increased to improve vehicle performance and acceleration, then power and speed are improved, but traction may be lost causing wheel slip and reduced control
Solution Approach 1:
The controller dynamically adjusts torque parameters by determining a traction torque range based on real-time vehicle operating conditions (wheel speeds, vehicle speed, longitudinal/lateral acceleration, coefficient of friction). The proposed torque distribution is modified to ensure it falls within this range, preventing wheel slip while maintaining performance.
Solution Approach 2:
The system uses feedback from traction signals indicating vehicle operating conditions to continuously monitor and adjust torque distribution. The controller compares proposed torque with the determined traction torque range and generates control signals to keep actual torque within acceptable limits, ensuring traction is maintained.
2Use of energy by moving object
If torque distribution is optimized for efficiency, then energy consumption is reduced, but vehicle dynamics attributes such as traction and stability may be compromised
Solution Approach 1:
The torque distribution is made dynamic rather than static. The controller continuously determines a proposed torque distribution that balances efficiency with vehicle dynamics requirements, adjusting in real-time based on changing operating conditions to maintain both efficiency and stability.
Solution Approach 2:
The system modifies torque distribution parameters to ensure they fall within the determined traction torque range while seeking efficient operation. The controller balances energy efficiency goals with the need to maintain vehicle dynamics by adjusting torque allocation between propulsion units based on real-time conditions.
3Reliability
If complex control algorithms are used to optimize torque split, then vehicle performance and traction control are improved, but controller complexity increases
Solution Approach 1:
The control function is segmented into distinct steps: receiving torque request and traction signals, determining traction torque range, determining proposed torque distribution, comparing proposed torque with traction range, and generating control signals. This modular approach manages complexity while maintaining effective control.
Solution Approach 2:
The proposed torque distribution acts as an intermediary between the driver's torque request and the actual torque applied to wheels. The controller uses this intermediate proposed distribution to balance multiple competing requirements (performance, efficiency, traction) before final torque application.
Data Source
AI summary
A controller is provided for a vehicle having front and rear axles, each axle having two wheels, and first and second propulsion units. The controller controls the first and second propulsion units to generate a combined torque with reference to a total requested torque. The controller is configured to: receive a torque request signal; receive traction signals indicating available traction at at least one wheel; determine a traction torque range defined by a maximum and minimum torque for at least one of the at least first or second propulsion units in dependence on one or more of the traction signals; determine a proposed distribution of torque between each of the at least first and second propulsion units with reference to the total requested torque; and determine a proposed torque to be generated by each of the at least first and second propulsion units in dependence on the proposed distribution of torque.