Electric Vehicle Braking Control via Regenerative Friction Force Distribution
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Solution Overview
Problem
Conventional control apparatuses for electric vehicles fail to manage front-rear torque distribution effectively when regenerative torque is limited, leading to potential wheel locking and destabilization of the vehicle, reducing drivability.
Innovation Solution
A control apparatus that calculates regenerative braking forces for both front and rear motors based on requested braking force and power limits, and adjusts frictional braking forces accordingly to maintain ideal braking force distribution, preventing wheel locking and stabilizing vehicle behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative braking force is limited due to battery power limitation, then power source protection is improved, but braking force distribution deviates from ideal ratio causing vehicle destabilization
Solution Approach 1:
The frictional braking force acts as an intermediary to compensate for the limited regenerative braking force. When the battery cannot accept full regenerative power, the frictional brake system supplements the braking force to maintain the ideal front-rear braking distribution ratio, preventing vehicle destabilization while protecting the power source
Solution Approach 2:
The control apparatus dynamically adjusts the frictional braking force parameter based on the regenerative braking force reduction amount. By changing the frictional brake activation level in response to battery power limitations, the system maintains optimal braking force distribution across different operating conditions
2Reliability
If regenerative braking force is reduced due to power limit, then battery charging safety is improved, but rear wheel locking is prevented, however front wheel may lock early reducing drivability
Solution Approach 1:
The control apparatus applies different braking strategies to front and rear wheels based on their specific characteristics and the regenerative braking force reduction amount. The frictional braking force is distributed with a front-rear ratio that differs from the ideal braking force distribution ratio, optimizing local wheel behavior to prevent early front wheel locking and maintain drivability
Data Source
AI summary
An object of the present invention is to provide a control apparatus for an electric vehicle capable of preventing the vehicle from being destabilized because a rear wheel is locked first or drivability from reducing because a front wheel is locked early. A control apparatus includes a regenerative braking force calculation portion configured to calculate a regenerative braking force to be generated on each of a front motor and a rear motor based on a request braking force requested to an electric vehicle, a power limit portion configured to reduce the regenerative braking force based on a power limit on a power source, and a frictional braking force output portion configured to output an instruction for generating a frictional braking force according to a regenerative braking force reduction amount, which is an amount of a reduction in the regenerative braking force by the power limit portion, to a brake apparatus.