Dual-Motor AWD Torque Map Control for EV Efficiency
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Solution Overview
Problem
Existing electric vehicles with two electric motors face inefficiencies due to the lack of a mechanical connection between the front and rear axles, leading to suboptimal torque distribution and increased installation space requirements, which complicates the implementation of all-wheel drive systems.
Innovation Solution
A method utilizing a characteristic map to manage torque distribution between the two electric motors based on driver input and vehicle speed, allowing for discontinuous transitions between different system states, where one or both axles are driven, optimizing efficiency by activating or deactivating motors and adjusting gear ratios, and incorporating predictive systems to minimize state changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical all-wheel drive setup is used, then traction and climbing ability are improved, but efficiency deteriorates and installation space increases
Solution Approach 1:
The drivetrain is segmented into independent front and rear axle electric motors, allowing each motor to operate independently based on actual driving conditions. This segmentation enables the system to provide all-wheel drive capability when needed while allowing individual axles to be deactivated when not required, thus improving efficiency while maintaining traction capability.
Solution Approach 2:
The system dynamically switches between different drive modes (front-wheel drive, rear-wheel drive, and all-wheel drive) based on real-time conditions such as vehicle speed, torque demand, and battery state of charge. This dynamic adaptability allows the system to optimize efficiency by deactivating motors during single-axle operation while maintaining the capability for all-wheel drive when traction is required.
2Reliability
If both electric motors are continuously activated, then all-wheel drive capability is maintained, but energy consumption increases
Solution Approach 1:
Instead of continuously activating both motors, the system applies partial action by selectively activating only the necessary motor(s) based on current driving conditions. The control strategy determines when single-motor operation is sufficient and when dual-motor operation is required, thereby reducing energy consumption while maintaining all-wheel drive capability when needed.
Solution Approach 2:
The system changes operational parameters by switching between different torque distribution strategies and motor activation states. The characteristic map defines different torque distributions for different operating regions, allowing the system to optimize energy consumption by selecting appropriate parameter combinations based on vehicle speed, torque demand, and battery state of charge.
3Loss of energy
If frequent state changes are implemented for torque distribution optimization, then efficiency is improved, but driving comfort deteriorates due to motor derating risks
Solution Approach 1:
The system performs preliminary actions by predicting future driving conditions and proactively adjusting motor activation states before transitions are required. This predictive approach allows the system to minimize frequent state changes by anticipating when torque distribution adjustments will be needed, thereby maintaining efficiency while avoiding unnecessary transitions that could compromise driving comfort or risk motor derating.
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 torque distribution, reducing energy consumption and improving drivability by optimizing motor usage and gear selection, while minimizing the risk of motor derating and maintaining driving comfort by reducing frequent state changes.
Implementation Method 1
When a motor is deactivated, it is separated from the drive train by means of a clutch
Data Source
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AI summary
A method for operating a vehicle, wherein the vehicle has at least a first and a second electric motor, wherein the first electric motor can drive a front axle of the vehicle and the second electric motor can drive a rear axle of the vehicle, wherein the first and second electric motors are operated with a torque dependent on a characteristic map, wherein the characteristic map defines delimited areas depending on a driver-requested torque and a vehicle speed, with discontinuously different torque distributions for the first and the second electric motor.