EV Battery Contactor Protection Using an Active Sacrificial Fuse
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Solution Overview
Problem
Power control systems for electric vehicles face challenges in coordinating protection using contactors and fuses due to coverage gaps and difficulty in operating them within a desired reaction time, especially during current spikes and other fault conditions.
Innovation Solution
The implementation of an active sacrificial protection device (ASPD) with a sacrificial contactor and fuse, connected in parallel with main contactors, which creates a current divider to reduce current through the main contactors and allows them to be opened, preventing damage from high current spikes, and can be controlled based on battery state of charge, health, and temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contactors and fuses are used to protect battery packs from current spikes, then component protection is improved, but coordination difficulty and response time worsen
Solution Approach 1:
The patent introduces an intermediary control system with current sensors and a controller that mediates between the fault condition and the protection devices. The controller receives current signals, determines fault conditions, and selectively opens contactors based on the nature and location of faults, thereby simplifying the coordination complexity while maintaining reliable protection.
Solution Approach 2:
The system employs feedback through current sensors that continuously monitor current flow and provide signals to the controller. This feedback mechanism enables real-time detection of current spikes and fault conditions, allowing the controller to respond appropriately by opening specific contactors, thus improving both protection reliability and response time.
2Reliability
If traditional fuses and contactors are used for protection, then component isolation is achieved, but response time to fault conditions worsens
Solution Approach 1:
Current sensors provide real-time feedback on current conditions to the controller, enabling immediate detection of fault conditions. This feedback loop eliminates the delay inherent in passive fuse operation, allowing the active control system to open contactors rapidly in response to detected faults, thereby reducing response time while maintaining effective isolation.
Solution Approach 2:
The patent replaces the purely mechanical/passive fuse operation with an active electronic control system. The controller uses electronic switching via contactors instead of relying solely on mechanical fuse blowout, enabling faster and more precise response to fault conditions, thus reducing reaction time while achieving the same isolation function.
3Reliability
If contactors are opened during fault conditions, then component protection is improved, but coverage gaps in protection worsen
Solution Approach 1:
The protection system is segmented into multiple independent contactors (first contactor, second contactor, third contactor) that can be selectively opened based on the specific fault location and nature. This segmentation allows the system to provide targeted protection for different circuit segments, eliminating coverage gaps by ensuring that at least one protective path is available for each potential fault scenario.
Solution Approach 2:
The system dynamically adapts its protection strategy based on real-time fault detection. The controller selectively opens specific contactors based on the detected fault location and type, providing optimized protection coverage for each scenario. This dynamic response ensures comprehensive protection without the fixed limitations of traditional fuse-only approaches.
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 ASPD effectively reduces the risk of damage from current spikes by providing an alternate current path, allowing the main contactors to be opened before the sacrificial fuse blows, thus protecting the battery pack and other components, and improving protection response times.
Implementation Method 1
A current sensor is configured to sense a measured load current flowing through one of the first contactor and the second contactor
Implementation Method 2
An active sacrificial protection device (ASPD) with a sacrificial contactor and fuse, connected in parallel with main contactors, which creates a current divider to reduce current through the main contactors
Data Source
AI summary
A power control system for a battery system of a vehicle includes a first contactor, a second contactor, N fuses and N vehicle loads. An active sacrificial protection device includes a third contactor and a first fuse. The active sacrificial protection device is connected to a positive or negative terminal of the battery system. A current sensor is configured to sense a measured load current flowing through one of the first contactor and the second contactor. A battery management module is configured to selectively close the third contactor to reduce current flowing through one of the first contactor or the second contactor and selectively open the one of the first contactor or the second contactor after closing the third contactor.