Electric Vehicle Torque Controller Cornering Dynamics
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Solution Overview
Problem
Electric vehicle driving systems with independent left and right wheel motors face challenges in maintaining torque difference during cornering, which affects cornering performance, as the torque difference between wheels decreases with increasing demand torque, leading to insufficient motor output and response to driver requests.
Innovation Solution
A driving-force controller that detects driver operations, calculates demand torque and torque difference, and prioritizes between demand torque and torque difference modes based on accelerator pedal position and steering angle to maintain optimal torque distribution between left and right wheels, ensuring improved cornering performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the motors output maximum power to meet driver demand torque, then the driver's acceleration request is achieved, but the torque difference between left and right wheels becomes smaller, reducing cornering performance
Solution Approach 1:
The control system dynamically adjusts the priority between demand torque mode and torque difference mode based on the degree of acceleration requirement. During cornering, when acceleration requirement is low, the system prioritizes torque difference to improve cornering performance. When acceleration requirement increases, the system dynamically switches to prioritize demand torque to meet driver acceleration requests, thus adapting to changing driving conditions
Solution Approach 2:
The system changes the control parameter priority based on the degree of acceleration requirement. By detecting accelerator pedal operation, the system determines whether to prioritize torque difference (for cornering) or demand torque (for acceleration) and adjusts the torque distribution accordingly, resolving the contradiction between cornering performance and acceleration response
2Ease of operation
If the torque difference between left and right wheels is maintained during cornering, then cornering performance is improved, but the total motor output becomes insufficient to meet driver acceleration requests
Solution Approach 1:
The system dynamically switches between torque difference mode and demand torque mode based on real-time detection of acceleration requirements. When the degree of acceleration requirement exceeds a threshold during cornering, the system transitions from prioritizing torque difference to prioritizing demand torque, ensuring sufficient total output while maintaining cornering capability when appropriate
3Productivity
If the system prioritizes demand torque generation, then driver acceleration requests are met, but the torque difference needed for cornering is reduced
Solution Approach 1:
The system changes the priority parameter between the two control modes based on the degree of acceleration requirement detected during cornering. By using accelerator pedal position and operation rate as input, the system determines whether to prioritize torque difference or demand torque, dynamically adjusting the torque distribution to balance cornering performance and acceleration response
Data Source
AI summary
A driving-force controller for an electric vehicle including at least two motors that independently drive left and right wheels, includes a detector that detects driving operation by a driver, and a controller that calculates a demand torque Tr of the driver, the torque difference ΔT applied to the left and right wheels during cornering, left and right torque-difference maintaining torques TLK and TRK of the motors when generating the demand torque Tr while maintaining the torque difference ΔT, and controls the motors based on the torque-difference maintaining torques TLK and TRK. The controller determines the priorities of a demand torque mode that generates the demand torque Tr and a torque difference mode that generates the torque difference ΔT depending on the driving operation detected by the detector.