Wheel-Specific Brake Control for Regenerative Deceleration Limits
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Solution Overview
Problem
Existing electric drive systems in motor vehicles face limitations in regenerative power, leading to reduced steerability, increased braking distance, and longitudinal acceleration disturbances due to the structural inability to control wheel-specific deceleration on non-ideal surfaces and uneven normal force distributions.
Innovation Solution
A centralized control system specifies torque target values and rotational speed limit values for each wheel and axle, coordinating actuators including wheel brake devices and drive devices to achieve optimal deceleration by dynamically distributing power between friction brakes and electric drives, ensuring high-frequency actuation at the wheel level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electric drive systems are used for deceleration, then energy recovery is improved, but deceleration power is limited due to regenerative power constraints
Solution Approach 1:
The braking system is segmented into multiple independent actuators: electric drive devices for energy recovery and friction brake devices for additional deceleration power. Each actuator can be controlled independently to optimize the balance between regenerative braking and friction braking based on current operating conditions.
Solution Approach 2:
The patent combines electric drive devices with friction brake devices into a unified braking system. This merging allows the system to leverage both regenerative braking capabilities and friction braking power, achieving superior overall deceleration performance while maintaining energy recovery benefits.
2Power
If electric drive systems are used for deceleration, then steerability is reduced on non-ideal surfaces, but friction brakes provide better wheel-specific control
Solution Approach 1:
The system segments the braking function to the wheel level by equipping each wheel with both electric drive and friction brake actuators. This segmentation enables independent control of each wheel's deceleration, maintaining steerability and handling characteristics even on non-ideal surfaces by allowing differential braking between left and right wheels.
Solution Approach 2:
The patent implements local quality by providing wheel-specific control capabilities through individual actuators at each wheel. This allows the system to apply different braking forces to different wheels based on local road conditions, maintaining optimal steerability and stability.
3Power
If electric drive systems are used for deceleration, then braking distance increases on non-ideal surfaces, but coordinated control can optimize performance
Solution Approach 1:
The system incorporates feedback mechanisms that continuously monitor wheel speeds, vehicle deceleration, and road conditions. This feedback enables the control system to dynamically adjust the contribution of electric drive and friction brake actuators, optimizing braking distance by maximizing deceleration power while preventing wheel lockup and maintaining steering control.
Solution Approach 2:
The patent implements dynamic control that continuously adapts the braking strategy based on real-time operating conditions. The system dynamically switches between electric drive deceleration and friction brake deceleration, and between proportional and individual wheel braking, to optimize braking distance across varying road surfaces and vehicle states.
4Power
If multiple actuators are coordinated for deceleration, then control complexity increases, but deceleration performance is improved
Solution Approach 1:
The control system is segmented into hierarchical levels: a central control unit that manages overall deceleration strategy and individual wheel control units that execute specific actuator commands. This segmentation reduces control complexity by distributing computational tasks and allowing modular development of control algorithms.
Solution Approach 2:
The patent implements a universal control architecture that can manage multiple types of actuators (electric drive and friction brakes) using common control principles and algorithms. This multi-functionality reduces control complexity by providing a unified framework that handles different actuator types consistently rather than requiring separate control systems for each actuator type.
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 maximum deceleration power and stability across varying road conditions by independently controlling actuators, minimizing wheel slip and maintaining optimal deceleration performance.
Implementation Method 1
the first wheel, in particular assigned to a left-hand side of the motor vehicle, is assigned a first wheel brake device with a controllable first actuator, in particular an electric machine
Implementation Method 2
the friction brake takes over not only the power difference but also the high-frequency torque modulation
Data Source
AI summary
A method for operating a motor vehicle. The motor vehicle has at least one axle with a first and a second wheel, wherein the first wheel, assigned to a left-hand side of the motor vehicle, is assigned a first wheel brake device with a controllable first actuator, the second wheel, assigned to a right-hand side of the motor vehicle, is assigned a second wheel brake device with a controllable second actuator. As a function of a braking request for a maximum deceleration of the motor vehicle, at least one torque target value and one rotational speed limit value are specified, and, for fulfilling the braking request, the actuators are controlled as a function of the specified torque target value and the specified rotational speed limit value.