EV Torque Distribution Control for Tire Diameter Mismatch
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Solution Overview
Problem
In electric vehicles, inappropriate torque distribution can occur due to differential rotation between wheels with different tire diameters, affecting vehicle turning characteristics and performance.
Innovation Solution
A torque distribution control method that calculates a correction value for torque distribution based on the deviation between actual and target values, and limits this correction using an I-term limiter to ensure appropriate torque distribution, particularly in electric four-wheel-drive vehicles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque distribution is corrected based on differential rotation between wheels, then slip correction is improved, but inappropriate torque distribution occurs when differential rotation is caused by tire diameter differences
Solution Approach 1:
The patent changes the control parameter from raw differential rotation to limited differential rotation. By introducing a limitation value based on vehicle speed and torque distribution ratio, the system transforms the parameter to filter out inappropriate corrections caused by tire diameter differences while preserving necessary slip corrections.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the differential rotation, comparing it against the limitation value, and adjusting the torque distribution accordingly. When the differential rotation exceeds the limitation, the correction is restricted, creating a closed-loop control system that prevents inappropriate torque distribution.
2Measurement precision
If correction value is calculated based on deviation between actual and target parameter values, then correction precision is improved, but correction value becomes inappropriate when parameter changes are caused by factors other than slip
Solution Approach 1:
The patent transforms the correction approach by introducing a limitation parameter that depends on vehicle speed and torque distribution ratio. This parameter change allows the system to maintain precision in calculating correction values while ensuring reliability by restricting corrections to physically appropriate ranges.
Solution Approach 2:
The limitation value is dynamically adjusted based on vehicle speed and torque distribution ratio. This dynamic adaptation allows the system to accommodate varying operating conditions while preventing inappropriate corrections, making the control system both precise and reliable across different driving scenarios.
Data Source
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AI summary
A torque distribution control method for an electric vehicle that performs torque distribution control for a plurality of driving wheels, the torque distribution control method including calculating a torque distribution value of any one of the plurality of driving wheels based on a first parameter, and calculating a correction value for the torque distribution value based on a deviation between an actual value and a target value of a second parameter, and correcting the torque distribution value with the calculated correction value, wherein the correction value is limited based on the torque distribution value.