All-Wheel-Drive Electric Vehicle Torque Allocation Control
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Solution Overview
Problem
All-wheel-drive electric vehicles face challenges in providing a driver with a sensation of acceleration at high speeds due to the reduction in output torque of electric motors as vehicle speed increases, limiting their ability to accelerate effectively when the driver steps on the accelerator pedal.
Innovation Solution
The implementation of a control unit that dynamically allocates driving force between front and rear electric motors, biasing towards the rear wheels when the accelerator is pressed hard at high speeds, reducing front motor torque and increasing rear motor torque to simulate acceleration sensations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electric motors are used to drive wheels directly in an all-wheel-drive electric vehicle, then the vehicle achieves compact design and high efficiency, but the output torque reduces as vehicle speed increases, limiting acceleration capability at high speeds
Solution Approach 1:
The patent segments the drive system into front and rear electric motors, allowing independent control of each motor's torque output. This segmentation enables the control unit to dynamically adjust torque distribution between front and rear wheels, and to create artificial acceleration sensations by differentially controlling motor torque even when overall vehicle speed is high and total output torque is reduced.
2Ease of operation
If the vehicle operates at high speed, then the vehicle achieves efficient cruising, but the driver experiences reduced acceleration sensation when the accelerator is pressed
Solution Approach 1:
The patent implements dynamic torque distribution control where the control unit continuously adjusts the torque allocation between front and rear electric motors based on accelerator operation amount and vehicle speed. At high speeds, when the driver presses the accelerator, the system dynamically increases torque to one or both motors to create artificial acceleration sensations, making the driving experience more responsive and engaging despite the natural torque reduction at high speeds.
3Ease of operation
If torque is increased at high speed to improve acceleration sensation, then the driver experiences better acceleration response, but energy consumption increases
Solution Approach 1:
The patent changes the torque distribution parameters between front and rear motors based on operating conditions. When acceleration sensation is desired at high speed, the control unit adjusts torque parameters to provide enhanced acceleration feel. The system intelligently manages energy consumption by only increasing torque when acceleration sensation is requested, rather than maintaining high torque continuously, thus balancing driver experience with energy 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 solution enables drivers to experience acceleration sensations at or above the vehicle's actual acceleration by adjusting torque distribution, enhancing the vehicle's ability to accelerate in high-speed ranges where motor output is reduced.
Implementation Method 1
magnet torque resulting from attraction and repulsion between the permanent magnet and a coil
Implementation Method 2
The reluctance torque is combined with magnet torque resulting from attraction and repulsion between the permanent magnet and a coil
Data Source
AI summary
An all-wheel-drive electric vehicle includes one or more front electric motors, one or more rear electric motors, an accelerator sensor, a vehicle speed sensor, and a control unit. The one or more front electric motors are configured to directly drive front wheels. The one or more rear electric motors are configured to directly drive rear wheels. The accelerator sensor is configured to determine an operation amount of an accelerator. The vehicle speed sensor is configured to determine vehicle speed. The control unit is configured to control drive of the one or more front and rear electric motors based on the operation amount of the accelerator and the vehicle speed. The control unit is configured to change an allocation of driving force between the one or more front electric motors and the one or more rear electric motors with a bias toward the rear wheels in a case where the operation amount of the accelerator is increased at or above a predetermined rate in a state in which the vehicle speed is higher than or equal to a predetermined speed.