Adaptive Temporal Filtering for Regenerative Braking Signal Stability
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Solution Overview
Problem
Regenerative braking in electric vehicles can cause abrupt transitions in active safety systems, leading to oscillations and reactivations, compromising vehicle steerability and safety, while high engine braking simulation values aim to maximize energy recovery.
Innovation Solution
A method involving temporal filtering of arbitrated braking signals to attenuate sudden variations, reconciling high engine braking with safety and comfort by integrating signals from the accelerator pedal and active safety systems, using linear or non-linear filters to manage transitions and setpoints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If high engine braking simulation values are used to maximize energy recovery, then energy recovery is improved, but abrupt transitions in active safety systems occur causing oscillations and reactivations
Solution Approach 1:
The patent applies dynamics by making the filtering time constant adjustable rather than fixed. The time constant is adapted based on the operating state of the vehicle and the magnitude of the regenerative braking torque, allowing the system to dynamically balance between energy recovery and safety system stability. When safety systems are active, a larger time constant smooths transitions; when inactive, a smaller time constant maximizes energy recovery.
Solution Approach 2:
The patent changes the parameter of filtering time constant based on system state. By adjusting this parameter according to whether active safety systems are in control state or normal state, and according to the regenerative braking torque magnitude, the system optimizes both energy recovery and prevents safety system oscillations.
2Reliability
If temporal filtering is applied to attenuate sudden variations in braking signals, then active safety system stability is improved, but energy recovery is reduced due to smoothed transitions
Solution Approach 1:
The filtering time constant is made dynamic rather than fixed. It increases when active safety systems are in control state or when regenerative braking torque is high, providing stronger smoothing. When these conditions are not met, the time constant decreases, allowing more aggressive braking and better energy recovery.
Solution Approach 2:
The system preliminarily applies stronger filtering when detecting that active safety systems are in control state or when regenerative braking torque exceeds a threshold, preventing potential oscillations before they occur. This proactive adjustment of the time constant ensures safety system stability while allowing maximum energy recovery when conditions permit.
Data Source
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AI summary
The invention relates to a method for adapting the engine-braking simulation for a vehicle provided with regenerative braking means, comprising: generating an arbitrated braking signal (Carb) based on a simulated engine-braking signal (Cfm) developed from signals from an acceleration pedal, and based on at least one signal (Formula I) from at least one active safety system; and generating a braking instruction (C) for the regenerative braking means by time filtration of the arbitrated braking signal.