EV Brake Pressure Control With Regenerative Torque Balancing
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Solution Overview
Problem
Existing brake systems for electrically driven vehicles are complex, costly, and lack fail-safe mechanisms for controlling brake pressures and recovering kinetic energy, particularly in systems with central control of multiple axles and steering systems.
Innovation Solution
A brake system with a central brake management system and slave control devices for electric axles, using open-loop and closed-loop control to manage brake pressures and recover energy, incorporating multiplex and PWM control for precise pressure regulation, and redundancy for fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a brake system with central control for multiple axles and energy recovery is implemented, then energy recovery capability and driving dynamics are improved, but system complexity and cost increase
Solution Approach 1:
The brake system is divided into independent brake circuits for different axles, with each circuit having its own pressure supply device. This segmentation allows the system to manage complexity by modularizing the control architecture while maintaining central coordination through the brake management system, enabling energy recovery without requiring a completely centralized complex system
Solution Approach 2:
The pressure supply device is designed to serve multiple functions: it can build up pressure for braking, reduce pressure for energy recovery, and operate in both directions (forward and backward piston movement or reversible rotary pump operation). This multi-functionality reduces the need for separate components for each function, thereby managing system complexity while achieving energy recovery
2Loss of energy
If a pressure supply device with bidirectional pressure control is used, then energy recovery capability is improved, but device complexity increases
Solution Approach 1:
Instead of using separate devices for pressure buildup and pressure reduction, the invention inverts the approach by using a single pressure supply device that can operate in reverse. The piston-cylinder unit moves backward, or the rotary pump reverses rotation direction, to reduce pressure in the brake circuit, enabling energy recovery without adding complex separate reduction mechanisms
Solution Approach 2:
The pressure supply device serves itself by using its own bidirectional capability to both build up and reduce pressure. The same electric motor and pump mechanism that generates pressure for braking can reverse to create negative pressure for energy recovery, eliminating the need for separate service devices and reducing overall system complexity
3Reliability
If redundant control systems are implemented for fail-safe operation, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The brake management system combines open-loop and closed-loop control functions into a single integrated control architecture. The central brake management coordinates with axle-specific slave control devices, merging redundancy at the control logic level rather than requiring completely separate physical systems. This integration achieves fail-safe operation while managing complexity through unified control software and shared hardware resources
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
Enables precise control of brake pressures, efficient energy recovery, and enhanced driving dynamics with redundancy for fail-safe operation, suitable for high-performance vehicles and autonomous driving.
Implementation Method 1
the pressure supply can both build up pressure and reduce pressure, in particular by forward and backward movement of the piston of the piston-cylinder unit or reversal of the direction of rotation of the rotary pump
Implementation Method 2
energy can be recovered by means of the traction motor during braking
Data Source
AI summary
A brake device for a motor vehicle with two axles in which at least one axle has an electric traction motor for driving and braking at least one wheel arranged on an axle, and in which energy can be recovered by means of the traction motor during braking, each wheel having a wheel brake. The brake device includes a pressure supply having an electric motor-driven pump in the form of a piston-cylinder unit or a rotary pump, which can both build up pressure and reduce pressure, and which is part of a pressure supply device. An open-loop and closed-loop control device controls the traction motor and components of the pressure supply device such that a braking deceleration can be set by closed-loop control individually for each brake circuit, each axle or wheel brakes of an axle, with different braking torques at the respective axles or wheel brakes of an axle.