Overcurrent Protection Circuit With Latched Fault Diagnostics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing overcurrent protection circuits in switch devices lack effective diagnostic output functions, leading to inadequate abnormality notification, particularly in cases of short circuits to ground, which can result in false reactions and failure to maintain a consistent abnormal state indication.
Innovation Solution
An overcurrent protection circuit is designed with an overcurrent detection unit, an output activation detection unit, and a logic unit that generates a diagnostic output signal. The logic unit shifts to an abnormal state when an overcurrent is detected and holds this state unless the output activation detection signal indicates a return to normal, preventing false reactions by ensuring the diagnostic output remains high even after the overcurrent detection signal returns to normal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the overcurrent protection circuit uses a simple overcurrent detection signal to indicate abnormality, then the device complexity is reduced, but the reliability of abnormality notification deteriorates due to false reactions during transient overcurrent conditions
Solution Approach 1:
The patent introduces an output activation detection signal as an intermediary to mediate between the overcurrent detection signal and the final diagnostic output. This intermediary signal helps distinguish between transient overcurrent conditions (normal operation) and genuine abnormalities (short circuits), thereby improving notification accuracy without significantly increasing circuit complexity
Solution Approach 2:
The patent implements a feedback mechanism where the output activation detection signal feeds back to the logic unit to modulate the diagnostic output based on the actual operational state. This feedback loop ensures that the diagnostic output accurately reflects genuine abnormalities while filtering out false reactions during transient conditions
2Speed
If the circuit immediately resets the diagnostic output when the overcurrent detection signal returns to normal, then the response speed is improved, but the reliability deteriorates due to false reactions during transient short circuits
Solution Approach 1:
The patent performs preliminary detection of the output activation state before resetting the diagnostic output. By checking whether the output is actually activated (indicating a genuine short circuit) before resetting, the circuit avoids false reactions during transient conditions while maintaining appropriate response speed for genuine abnormalities
3Reliability
If the circuit adds multiple detection signals and logic operations to improve diagnostic accuracy, then the reliability of abnormality notification is improved, but the device complexity increases
Solution Approach 1:
The patent makes the output activation detection signal serve multiple functions: it indicates whether the output is activated, helps distinguish transient from genuine overcurrent conditions, and modulates the diagnostic output. This multi-functionality improves diagnostic accuracy without proportionally increasing circuit complexity
Data Source
AI summary
Provided is an overcurrent protection circuit including an overcurrent detection unit configured to compare an output current flowing through a switch element and a predetermined overcurrent detection value to generate an overcurrent detection signal, an output activation detection unit configured to compare an output voltage and a predetermined threshold voltage to generate an output activation detection signal, a logic unit configured to combine the overcurrent detection signal and the output activation detection signal to generate a logic operation signal, and a diagnostic output unit configured to provide diagnostic output, the logic unit shifting the logic operation signal to a logic level of abnormal state when the overcurrent detection signal is shifted to a logic level of overcurrent detection state and holding the logic operation signal at that logic level, unless the output activation detection signal is shifted to a logic level of output activation state.