Over-Current Protection Circuit Using Digital Counter
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Solution Overview
Problem
Existing over-current protection methods, such as fuses, often result in irreversible events and may not accurately manage current pulses, leading to potential system malfunctions or safety hazards due to variations in tripping thresholds and characteristics.
Innovation Solution
A method and circuit that emulate the current handling capabilities of a power cable by monitoring current flow and using a digital counter with adjustable counting speeds and thresholds to control a switch, ensuring that the current does not exceed the cable's capabilities, thereby preventing over-current events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuse is used for over-current protection, then the cable is protected from over-current events, but the protection is irreversible and requires replacement after tripping
Solution Approach 1:
The patent implements a reusable over-current protection circuit that can recover and reset after detecting an over-current event. The circuit uses a microcontroller to monitor current conditions and control a solid-state switch, allowing the system to resume normal operation after the fault condition is cleared, eliminating the need for component replacement required by traditional fuses.
2Reliability
If a fuse with high current rating is used, then the cable's current capability is fully utilized, but the tripping threshold varies and may not accurately protect against over-current events
Solution Approach 1:
The patent employs a feedback mechanism where a current sense resistor continuously monitors the current flowing through the cable, and a microcontroller processes this information to detect over-current conditions. The system compares the measured current against predefined thresholds and provides precise control of the solid-state switch, ensuring accurate protection that fully utilizes the cable's current capability without the threshold variations inherent in fuse designs.
3Measurement precision
If a digital counter with adjustable thresholds is used, then the current monitoring precision is improved, but the device complexity increases
Solution Approach 1:
The patent integrates multiple functions into a single microcontroller unit that performs current monitoring, threshold comparison, counter operations, and switch control. This multi-functional approach achieves precise current monitoring with adjustable thresholds while minimizing overall circuit complexity by consolidating what would otherwise require separate discrete components into one programmable device.
Data Source
AI summary
A method of over-current protection includes: determining a current flowing through a first element to be protected, comparing the determined current with a plurality of thresholds, controlling a counter based on the comparing the determined current with a plurality of thresholds, and stopping the current flowing through the first element by activating a switch in series with the first element when an output of the counter reaches a predetermined counter threshold.