Heavy-Duty Brake Blending for Regenerative Slip Control
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Solution Overview
Problem
Existing methods for brake blending in heavy-duty vehicles face challenges in efficiently combining service brakes and regenerative brakes, requiring refined control strategies to handle different types of braking systems effectively.
Innovation Solution
A method for controlling a vehicle brake system that determines a total brake torque request, utilizes the electrical machine for slip control below a threshold, applies a baseline torque by the service brake system when the request exceeds the electrical machine's capability, and switches to service brake slip control for high demands, ensuring efficient and safe braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative brake system is used for light to moderate braking force and service brake system for moderate braking, then energy recovery is improved, but control complexity increases due to coordination between different brake types
Solution Approach 1:
The patent segments the braking operation into distinct phases: regenerative braking handles light to moderate braking forces, while service brakes handle moderate to hard braking. This segmentation allows each brake type to operate in its optimal range, simplifying the overall control strategy by clearly defining when to use each system.
Solution Approach 2:
The control system dynamically switches between regenerative and service braking based on real-time conditions including brake torque requests, vehicle speed, and brake system state. This dynamic adaptation allows the system to optimize energy recovery while maintaining simple control logic through condition-based decision making.
2Device complexity
If electrical machine handles slip control during most operations, then control simplicity is improved, but braking capability may be insufficient during high torque demands
Solution Approach 1:
The patent implements dynamic switching between electrical machine slip control and service brake slip control based on the magnitude of brake torque requests. For normal operations, the electrical machine handles slip control to simplify the system. When high torque demands are detected, the system dynamically transitions to service brake slip control, ensuring adequate braking capability while maintaining control simplicity through condition-based switching.
3Reliability
If service brake system is used for hard braking, then response time is reduced improving safety, but energy recovery capability is lost
Solution Approach 1:
The patent segments braking operations by intensity level, assigning regenerative braking to light to moderate forces and service brakes to moderate to hard forces. This segmentation ensures that energy recovery is maximized during conditions where it is effective, while service brakes provide rapid response for hard braking situations where safety is the priority and energy recovery is secondary.
Solution Approach 2:
The system accepts that service brakes cannot recover energy during hard braking events, but this limitation is converted into a benefit by using service brakes only when necessary for safety-critical high-torque situations. The clear distinction between regenerative and service brake operating ranges allows the system to optimize energy recovery during normal operations while ensuring safety during emergency braking.
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 simplifies control by allowing the electrical machine to handle slip during most operations, ensuring safe vehicle operation with reduced response time and enhanced safety through coordinated brake torque management.
Implementation Method 1
Electrically powered vehicles comprise one or more electrical machines arranged to power the vehicle. These electrical machines are often also capable of generating a decelerating force. Such braking may be regenerative in the sense that energy may be generated from the braking
Implementation Method 2
The service brakes on heavy duty vehicles are normally friction brakes, such as disc brakes or drum brakes
Data Source
AI summary
A method for controlling a vehicle brake system of a heavy duty vehicle, the brake system comprising a service brake system and an electrical machine brake system. The method includes determining a total brake torque request for braking a wheel of the vehicle, obtaining a brake torque capability of the electrical machine, determining if the total brake torque request exceeds the brake torque capability of the electrical machine, and if the total brake torque request exceeds the brake torque capability of the electrical machine but is below a threshold level, applying a baseline brake torque by the service brake system, wherein the baseline brake torque is configured to compensate for a difference between total brake torque request and brake torque capability of the electrical machine, and controlling wheel slip by the electrical machine brake system.