Resettable Electronic Fuse for High-Power Overcurrent Protection
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Solution Overview
Problem
Conventional fuses in battery packs and chargers can become permanently inoperable when they open due to high or excessive currents, leading to device malfunction and the need for repair, especially in high-power applications like power tools and battery pack chargers.
Innovation Solution
Implementing a resettable electronic fuse that can selectively interrupt current based on detected fault conditions and reset itself or be reset by a controller, replacing conventional fuses and semiconductor switches, thereby providing a smaller, cost-effective, and more efficient solution that complies with safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fuse is used to protect against high currents, then device protection is achieved, but the device becomes permanently inoperable when the fuse opens
Solution Approach 1:
The fuse is transformed from a static, one-time-use component to a dynamic, resettable component. The electronic fuse can transition between conductive and non-conductive states multiple times, allowing the device to be protected against overcurrent while maintaining operability after fault clearance through reset signals.
Solution Approach 2:
The electrical parameters of the protective device are made changeable. The electronic fuse's resistance changes from low (conductive) to high (non-conductive) state during fault conditions, and can be restored to its original state through resetting, unlike conventional fuses which permanently change state.
2Reliability
If conventional fuses and semiconductor switches are used together, then adequate protection is provided, but heat generation and space requirements increase
Solution Approach 1:
The functions of the conventional fuse and semiconductor switch are merged into a single electronic fuse component. This integrated component provides both overcurrent protection and switching capability, eliminating the need for separate heat-generating components and reducing overall heat generation in the circuit.
Solution Approach 2:
The electronic fuse is designed to perform multiple functions: overcurrent protection, circuit switching, and fault detection. This multi-functional component replaces what previously required multiple specialized components, reducing the total heat generation from multiple active elements.
3Reliability
If conventional fuses are used in high-power devices, then basic protection is achieved, but the devices require larger space and higher cost
Solution Approach 1:
Multiple protective and switching functions are combined into a single electronic fuse component, significantly reducing the circuit footprint. The integrated design eliminates the need for separate fuse holders, semiconductor switches, and associated mounting hardware, providing compact protection for high-power devices.
4Device complexity
If conventional fuses are used, then simple design is maintained, but repair requirements increase when fuses open
Solution Approach 1:
The electronic fuse provides self-service functionality by automatically detecting fault conditions and transitioning to a protective state without requiring external intervention. After the fault is cleared, the system can automatically or manually reset the fuse, eliminating the need for physical replacement and simplifying maintenance.
Data Source
AI summary
A resettable electronic fuse for a high-power device such as a power tool, a battery pack for the power tool, or a battery pack charger. The resettable electronic fuse is connected in a current path of the device and is operable or configured to selectively interrupt current through the resettable electronic fuse based on a detected condition of the device (e.g., a detected fault condition of the device). The resettable electronic fuse is also configured to be reset after a detected fault condition has ended. In some embodiments, the resettable electronic fuse is configured to reset itself. In other embodiments, the resettable electronic fuse is configured to receive a signal (e.g., from a device controller) to reset.