Battery Contactor-Fuse Coordination for Coverage Gap Isolation
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Solution Overview
Problem
Existing battery protection systems in electric and hybrid vehicles fail to effectively isolate the battery system from loads during current spikes within a 'coverage gap' region, where currents exceed the threshold for contactors but are below the threshold for fuses, potentially leading to prolonged exposure to fault conditions.
Innovation Solution
A protection system incorporating an auxiliary protection module that forms a short circuit between terminals using silicon controlled rectifier-based crowbar circuitry when currents are within the coverage gap region, ensuring timely disconnection of the battery system from loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contactors are used to isolate the battery system from loads, then protection against low-level overcurrent is provided, but protection is insufficient for currents within the coverage gap region (greater than contactor threshold but less than fuse threshold)
Solution Approach 1:
The protection system is segmented into multiple protective components with distinct current thresholds: contactors for low-level overcurrent (first current range), auxiliary protection module for intermediate currents (coverage gap region), and fuses for high-level overcurrent (second current range). Each component operates independently within its designated current range, providing comprehensive protection without requiring a single complex device to handle all current levels.
Solution Approach 2:
The auxiliary protection module acts as an intermediary component between the contactor and the fuse. It specifically addresses the coverage gap region by detecting currents that exceed the contactor threshold but remain below the fuse threshold, and responds by triggering the fuse to open. This intermediary component ensures continuous protection coverage without leaving gaps in the protection spectrum.
2Reliability
If fuses are used to protect against high current, then protection against severe overcurrent is provided, but response time is delayed compared to contactors for lower current ranges
Solution Approach 1:
Different protective responses are applied to different current ranges: the contactor provides rapid mechanical disconnection for low-level overcurrent, the auxiliary protection module provides electronic detection and fuse triggering for intermediate currents in the coverage gap region, and the fuse provides thermal-magnetic interruption for high-level overcurrent. Each component is optimized for its specific current range, ensuring appropriate response time and protection level for each scenario.
3Device complexity
If the protection system uses only contactor and fuse, then simple structure is maintained, but coverage gap region creates vulnerability to prolonged fault exposure
Solution Approach 1:
The auxiliary protection module continuously monitors current and is pre-configured with the exact thresholds for the coverage gap region (greater than first threshold, less than second threshold). When current enters this vulnerable range, the module immediately triggers the fuse to open, preventing prolonged fault exposure. This preliminary action ensures that the coverage gap vulnerability is eliminated without requiring complex real-time decision-making during fault conditions.
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
The auxiliary protection module effectively isolates the battery system from loads during current spikes within the coverage gap region, preventing damage by triggering fuses and ensuring timely disconnection, thus enhancing the safety and reliability of battery systems in vehicles.
Implementation Method 1
A protection system incorporating an auxiliary protection module that forms a short circuit between terminals using silicon controlled rectifier-based crowbar circuitry when currents are within the coverage gap region
Implementation Method 2
The auxiliary protection module effectively isolates the battery system from loads during current spikes within the coverage gap region, preventing damage by triggering fuses
Data Source
AI summary
A protection system for a battery system includes a battery control module configured to selectively open at least one contactor to isolate the battery system from a load in response to a sensed current being greater than a first threshold and within a first current range, at least one fuse connected between first and second terminals of the battery system and configured to open to isolate the battery system from the load in response to the sensed current being greater than a second threshold and within a second current range that is greater than and offset from the first current range, and an auxiliary protection module configured to selectively form a short circuit between first and second terminals in response to the sensed current being greater than the first threshold, less than the second threshold, and within a coverage gap region between the first and second current ranges.