Dual-Path Battery Charge Management for ASIL D Safety
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Solution Overview
Problem
Current battery management systems for electric vehicles cannot reliably prevent overvoltage-induced ignition of traction batteries, limiting their safety rating to ASIL C, despite the use of more reliable components, due to architectural constraints.
Innovation Solution
A dual-path management system is implemented, using separate means to compare voltage and control actuators to interrupt charging, ensuring that even if one path fails, the other can still detect and prevent overvoltage, with distinct microprocessors, analog-digital interfaces, and actuators to reduce the risk of simultaneous failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two separate paths are implemented to measure and interrupt charge, then safety rating is improved to ASIL D, but device complexity increases
Solution Approach 1:
The system is segmented into two independent functional paths, each capable of complete overvoltage detection and interruption. This segmentation achieves the ASIL D safety rating through functional redundancy while maintaining clear separation of components to manage complexity.
Solution Approach 2:
Each path is designed with specific local characteristics - the first path uses a charger as actuator while the second path uses relays as actuators. This local differentiation allows each path to be optimized independently, managing overall system complexity while achieving the required safety rating.
2Reliability
If distinct microprocessors and actuators are used in each path, then fault tolerance is improved, but manufacturing complexity increases
Solution Approach 1:
The system segments the control architecture into two independent microprocessors, each managing its own path with distinct actuators. This segmentation achieves high fault tolerance by ensuring that failures in one microprocessor or actuator do not affect the other path, while the modular nature facilitates standardized manufacturing processes.
Solution Approach 2:
The system uses two different types of microprocessors and different types of actuators (charger and relays) to create functional copies that are not identical but achieve the same safety objective. This approach to copying with variation reduces manufacturing complexity by allowing the use of different but equally reliable components from different suppliers.
Data Source
Figure 1
AI summary
The invention relates to a system (50) for managing the charging of at least one cell (11) of a storage battery (10), comprising: two separate means (110, 121, 122) for comparing the voltage (U) across the terminals of said cell (11) with a threshold voltage (Us); and two separate controlling means (122, 221) adapted to control two actuators (12, 13, 14), respectively, in order to interrupt the charging of the storage battery when said first or second comparing means detects that the voltage across the terminals of said cell exceeds the threshold voltage. One of the actuators is formed by a charger (14) that is connected to said storage battery in order to recharge said cells.