Regenerative Braking Control During Controller Link Interruptions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In vehicles with one pedal drive and combined regenerative and friction braking systems, communication issues between controllers can lead to ineffective braking torque distribution, necessitating a strategy to ensure safe vehicle slowdown without driver input.
Innovation Solution
A master controller calculates and distributes torque requests between regenerative and friction braking systems based on link tests and ramp schedules, adjusting ratios and values to ensure overall torque fulfillment, either by reducing regenerative braking or increasing friction braking as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the vehicle uses both regenerative and friction braking systems for one pedal drive, then braking control and energy recovery are improved, but system complexity and communication requirements increase
Solution Approach 1:
The braking system is divided into independent regenerative braking controller and friction braking controller modules, each handling specific braking functions. The master controller segments the overall braking torque request into regenerative and friction components, allowing independent control and fault isolation of each subsystem while maintaining simplified one-pedal drive operation.
Solution Approach 2:
The master controller acts as an intermediary between the driver's braking request and the two separate braking systems. It receives the overall braking torque request, calculates appropriate regenerative and friction braking distributions, and sends commands to respective controllers. This intermediary role simplifies the driver's operation while managing the complexity of coordinating multiple braking systems.
2Reliability
If the system continuously monitors communication links between controllers, then reliability is improved, but computational load and processing time increase
Solution Approach 1:
The system performs link tests between controllers at predetermined intervals rather than continuously, and pre-establishes default braking values and ramp schedules for fault scenarios. This preliminary preparation allows the system to quickly respond to communication failures without requiring complex real-time calculations, thus improving reliability while minimizing processing time delays.
Solution Approach 2:
Communication link monitoring is implemented as a periodic check at predetermined time intervals rather than continuous monitoring. This periodic approach maintains adequate communication reliability assessment while significantly reducing computational load and processing time compared to continuous monitoring, allowing the system to efficiently detect and respond to communication failures.
3Reliability
If the system reduces regenerative braking during communication issues, then safety is improved, but energy recovery efficiency decreases
Solution Approach 1:
During communication link failures, the system applies partial regenerative braking rather than complete disengagement, using a reduced regenerative braking ratio determined by ramp schedules. This partial action maintains some energy recovery capability while prioritizing safety by relying more on friction braking, achieving a compromise that recovers available energy without compromising braking reliability.
Solution Approach 2:
The system dynamically changes the regenerative braking ratio parameter based on communication link status. During normal operation, maximum regenerative braking is utilized for optimal energy recovery. When communication issues are detected, the regenerative braking ratio is reduced according to predetermined ramp schedules, allowing the system to adapt energy recovery levels to safety requirements while still maintaining partial regenerative braking capability.
Data Source
AI summary
A braking control system includes a regenerative brake controller, a friction brake controller, and a master controller. The regenerative brake controller, in response to absence of expected communication between the master controller and regenerative brake controller, decreases regenerative braking. The master controller, in response to detecting the decrease in regenerative braking, commands the friction brake controller to increase friction braking.