Braking Torque Distribution for Electric Vehicle Energy Recovery
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Solution Overview
Problem
Current braking systems in electric vehicles face inefficiencies in distributing braking torque to maximize energy recovery while maintaining driving stability and dynamics, particularly in varying stability conditions.
Innovation Solution
A method that dynamically adjusts the distribution of braking torque between axles based on the efficiency of electric machines and driving stability, using a combination of recuperation torque from electric machines and friction torque from brakes, with different distribution sequences for non-critical, imminent instability, and critical driving situations to ensure maximum energy recovery and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If braking torque is distributed to maximize recuperation torque from electric machines, then brake energy recovery efficiency is improved, but driving stability may deteriorate in critical situations
Solution Approach 1:
The patent implements dynamic switching between different braking torque distribution strategies based on real-time driving stability assessment. The system transitions from an efficiency-optimized distribution (maximizing recuperation) to a stability-optimized distribution (ensuring safe braking) when instability is detected, and vice versa when stability is confirmed. This dynamic adaptation resolves the contradiction by allowing the system to prioritize energy recovery during stable conditions while switching to stability prioritization when needed.
Solution Approach 2:
The system changes the distribution parameters of braking torque between axles based on detected driving stability conditions. When instability is detected, the control unit modifies the torque distribution ratios to ensure stable braking, otherwise it optimizes for maximum energy recovery. This parameter adjustment allows the system to balance between energy efficiency and driving stability across different operating conditions.
2Stability of the object's composition
If braking torque is distributed to ensure vehicle stability, then driving safety is improved, but brake energy recovery efficiency deteriorates
Solution Approach 1:
The system dynamically adjusts the braking torque distribution strategy based on real-time stability assessment. During stable driving conditions, it switches to an efficiency-optimized mode that maximizes energy recovery. When instability is detected, it transitions to a stability-optimized mode. This dynamic switching resolves the contradiction by allowing the system to prioritize energy recovery when safe, while ensuring stability when needed.
Solution Approach 2:
The control unit modifies the torque distribution parameters between axles based on the detected stability condition. In stable conditions, parameters are optimized for maximum recuperation torque. When instability is detected, parameters are adjusted to ensure stable braking distribution. This parameter adaptation allows the system to balance energy recovery and stability across different operating states.
3Stability of the object's composition
If friction braking torque is used to ensure stable braking, then driving dynamics are improved, but energy recovery from electric machines is reduced
Solution Approach 1:
The system implements dynamic switching between recuperation-optimized braking and friction-optimized braking based on real-time stability assessment. During stable driving, it maximizes electric machine recuperation torque. When instability is detected, it increases friction braking torque to ensure stable deceleration. This dynamic adjustment resolves the contradiction by allowing friction braking to supplement or replace recuperation braking only when necessary for stability.
Solution Approach 2:
The control unit dynamically adjusts the ratio of friction braking torque to total braking torque based on detected stability conditions. In stable conditions, the friction braking ratio is minimized to maximize energy recovery. When instability is detected, the friction braking ratio is increased to ensure stable braking. This parameter modulation allows the system to balance energy recovery and braking stability.
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
This approach ensures high efficiency in braking energy recovery across a wide range of driving stabilities, reduces the need for additional friction torque, and maintains stable driving dynamics by optimizing torque distribution between electric machines and friction brakes.
Implementation Method 1
an electric machine assigned to the first axle... a second friction brake device and a second electric machine... a first recuperation torque component to be provided by the first electric machine... a second recuperation torque component to be provided by the second electric machine
Data Source
Figure 1
AI summary
The invention relates to a method for distributing a braking torque (FBM), requested by a driver, over the axles (A1, A2) of a motor vehicle, wherein the wheels (12, 14) of the first axle (A1) are associated with a first friction braking device (20-1) and a first electrical machine (22-1) having a first efficiency (n1), and the wheels (16, 18) of the second axle (A2) are associated with a second friction braking device (20-2) and a second electrical machine (22-2) having a second efficiency (n2). In accordance with the method, the requested braking torque (FBM) is distributed over the first and/or second axle (A1, A2) and the proportions of the recovery torques (RK1, RK2) available from the first and/or second electrical machine (22-1, 22-2) at the requested braking torque (FBM) are determined by taking into account the current driving stability of the motor vehicle.