EV Braking Control With Non-Linear Deceleration to Reduce Vibration
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Solution Overview
Problem
Longitudinal vibration occurs in electric vehicles during automatic braking due to the combination of motor and hydraulic brake operations, affecting braking quality and marketability.
Innovation Solution
A non-linear deceleration profile is generated for automatic braking, determining motor-alone braking feasibility based on motor temperature and battery state of charge, and using hydraulic brakes to minimize vibration by adjusting deceleration rates and operation timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If motor and hydraulic brake are connected for automatic braking, then braking functionality is improved, but longitudinal vibration occurs
Solution Approach 1:
The patent applies dynamics by implementing a non-linear deceleration profile that dynamically adjusts deceleration rates across different braking phases. The profile transitions from high deceleration at the beginning to low deceleration in later stages, preventing the constant force application that causes longitudinal vibration while maintaining effective braking functionality throughout the stopping process.
Solution Approach 2:
The patent changes the deceleration parameter from a constant linear rate to a variable non-linear rate. By modifying the deceleration profile to have different rates in different phases (higher initially, lower subsequently), the system achieves smooth braking without the vibrations caused by uniform deceleration, while still utilizing both motor and hydraulic brake components.
2Object-affected harmful factors
If non-linear deceleration profile is used, then longitudinal vibration is minimized, but control complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-defining the non-linear deceleration profile before actual braking occurs. The control system has predetermined the optimal deceleration curve with its characteristic high-initial-rate and low-later-rate sections, allowing the system to simply follow this pre-planned trajectory during braking rather than calculating complex real-time adjustments, thus minimizing vibration without excessive control complexity.
3Reliability
If motor-alone braking is used, then braking quality is improved, but braking force may be insufficient at high temperatures
Solution Approach 1:
The patent applies dynamics by adaptively selecting between motor-alone braking and hybrid braking based on real-time motor temperature conditions. When the motor is within normal temperature ranges, motor-alone braking with non-linear profile provides smooth high-quality braking. When temperature exceeds thresholds, the system dynamically transitions to hybrid braking with the hydraulic brake to maintain sufficient braking force, ensuring reliable performance across all thermal conditions.
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
Minimizes longitudinal vibration, enhances braking quality, and improves marketability by optimizing deceleration profiles and brake usage.
Implementation Method 1
Electric vehicles can implement automatic braking through regenerative braking of a motor
Implementation Method 2
when a vehicle approaches a stop state, a hydraulic brake is used to achieve a complete stop state
Data Source
AI summary
A braking control method for electric vehicles, involving a non-linear deceleration profile for enhanced automatic braking, includes generating the present profile by a control device, assessing the feasibility of motor-alone braking, and implementing braking based on the profile using only the motor when appropriate. Additionally, the control device evaluates if the motor speed stays within a predetermined range during a set time before the expected stop. If the speed is within the range, the vehicle is brought to a complete stop using only the motor. This approach aims to optimize energy efficiency and ensure safe braking performance.