Regenerative Torque Control for Electric Vehicle Slip Prevention
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Solution Overview
Problem
Existing regenerative braking control systems for electric vehicles experience reduced deceleration feel on low μ roads, leading to a strange sensation when transitioning from low to high μ roads, and are prone to slip and rear wheel locking due to inadequate torque control.
Innovation Solution
A regenerative braking control apparatus that includes a road surface friction coefficient acquisition unit and a regenerative torque control unit, which reduces regenerative torque and increases the rising gradient of regenerative torque at the start of regeneration on low μ roads compared to high μ roads, ensuring consistent deceleration feel and preventing slip and rear wheel locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the regenerative braking control apparatus reduces the rising gradient of deceleration at the start of regenerative braking on low μ roads, then occurrence of slip is suppressed, but deceleration feel of driver reduces and feeling of strangeness occurs
Solution Approach 1:
The patent applies dynamics by making the regenerative torque control strategy adaptive based on road conditions. The control apparatus dynamically switches between two different torque profiles: one for high μ roads and another for low μ roads. This dynamic adaptation allows the system to optimize both slip suppression and deceleration feel according to the actual road friction coefficient, resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
The patent changes the parameters of regenerative torque control based on the detected road surface friction coefficient. When a low μ road is detected, the system changes the torque magnitude and rising gradient parameters to prevent slip. When a high μ road is detected, the system changes these parameters to provide better deceleration feel. This parameter adaptation resolves the contradiction by allowing optimal performance under different road conditions.
2Reliability
If the regenerative torque is reduced on low μ roads, then slip occurrence is suppressed, but deceleration feel becomes inconsistent compared to high μ roads
Solution Approach 1:
The system dynamically adapts its control characteristics based on road conditions. By detecting the road surface friction coefficient and switching between different torque control modes, the system maintains appropriate deceleration feel for each road type while preventing slip on low μ roads. This dynamic behavior ensures both reliability and adaptability.
Solution Approach 2:
The patent applies local quality by providing different torque control characteristics tailored to specific road conditions. Instead of using a uniform control strategy, the system applies locally optimized torque profiles: one set of parameters for high μ roads and another for low μ roads. This localized optimization resolves the contradiction by ensuring appropriate performance for each specific road condition.
3Ease of operation
If the rising gradient of regenerative torque is increased at start of regeneration on low μ roads, then deceleration feel is improved, but slip risk increases due to rapid torque increase
Solution Approach 1:
The patent resolves this contradiction by changing the torque profile parameters based on road conditions. On low μ roads, the system uses a specific combination of reduced torque magnitude and increased rising gradient that provides good deceleration feel without exceeding the friction limit. On high μ roads, different parameters are used. This parameter adaptation allows the system to simultaneously achieve good deceleration feel and slip prevention.
Solution Approach 2:
The system dynamically adjusts the torque rising gradient and magnitude based on real-time road condition detection. This dynamic control allows the system to optimize the balance between deceleration feel and slip risk for each specific road condition, resolving the contradiction by adapting the torque profile to match the available friction.
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
The system effectively suppresses slip and strangeness in deceleration feel by adjusting regenerative torque based on road friction, maintaining consistent deceleration experience across different road conditions and reducing rear wheel locking, while ensuring equal maximum deceleration values regardless of road friction.
Implementation Method 1
a regenerative braking control apparatus that performs braking by driving a generator using the rotational energy of wheels
Data Source
AI summary
A regenerative torque control unit is configured to reduce a regenerative torque and increase a rising gradient of the regenerative torque at a start of regeneration when a road surface friction coefficient acquired by a road surface friction coefficient acquisition unit is low as compared to when the road surface friction coefficient is high. Thus, it is possible to suppress occurrence of a slip on a low μ road, and it is less likely to provide a feeling of strangeness from a change between a low μ road and a high μ road.