Overcurrent Protection Circuit With Current-Dependent Blanking Time
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Solution Overview
Problem
Overcurrent protection circuits struggle with high peak-to-average current ratios, leading to either undetected currents causing damage or false tripping, due to fixed and magnitude-independent blanking timers.
Innovation Solution
The overcurrent protection circuit modulates the blanking time based on the magnitude of the current exceeding the set current, with the blanking time being inversely or proportionally related to the magnitude of the overcurrent, mimicking the behavior of a traditional fuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed blanking timer is used in overcurrent protection circuits, then the circuit can prevent false tripping during normal operation, but it cannot accurately distinguish between small overcurrent conditions and large overcurrent conditions, leading to either undetected damage or false tripping
Solution Approach 1:
The patent applies the dynamics principle by making the blanking time variable rather than fixed. The blanking time stage dynamically adjusts the blanking time value based on the magnitude of the load current. When the load current exceeds the predefined set current, the blanking time is modulated according to how much the current exceeds the threshold, allowing the protection circuit to adapt its response to different overcurrent conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the blanking time parameter based on the overcurrent magnitude. The compare stage determines that the blanking time value is higher than a reference value when the load current exceeds the set current by a certain magnitude. This changes the temporal parameter of the protection response based on the severity of the overcurrent condition, enabling differentiated protection responses.
2Ease of operation
If the trip current is set higher than the peak current to avoid false tripping, then false tripping is reduced, but small overcurrent conditions that are larger than the average current but smaller than the peak current go undetected and may cause system damage
Solution Approach 1:
The patent applies feedback by continuously monitoring the load current and comparing it against the predefined set current. The comparison result feeds back to the blanking time stage, which adjusts the blanking time value accordingly. This closed-loop feedback mechanism ensures that the protection circuit responds appropriately to different overcurrent magnitudes, preventing both false tripping and undetected damage conditions.
Solution Approach 2:
The patent implements preliminary action by establishing a predefined set current threshold before operation begins. The blanking time stage is pre-configured to start generating the blanking time value when the load current exceeds this predefined threshold. This preliminary setup enables the circuit to immediately respond to overcurrent conditions without requiring real-time calculation or adjustment of the threshold.
3Reliability
If a traditional fuse is used, then the circuit provides simple and reliable overcurrent protection, but it requires physical replacement after melting and cannot be reset automatically
Solution Approach 1:
The patent replaces the mechanical fuse system with an electronic protection circuit. Instead of using a physical element that melts and breaks the circuit, the invention uses semiconductor devices and electronic components to detect and respond to overcurrent conditions. The protection is achieved through electronic switching and control signals, eliminating the need for physical replacement and enabling automatic resetting.
Solution Approach 2:
The patent implements self-service by enabling the protection circuit to automatically detect, respond to, and reset from overcurrent conditions without human intervention. The electronic fuse can be reset automatically after the overcurrent condition is cleared, eliminating the need for manual replacement. The system serves itself by continuously monitoring and self-correcting when abnormal conditions occur.
Data Source
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AI summary
An over current protection circuit arranged for providing an over current signal (OC), the over current protection circuit includes a compare stage (5) arranged for determining that a blanking time value is higher than a predefined reference value, an output stage(7) arranged for outputting the over current signal based on the determination, a blanking time stage (1-4) arranged for generating the blanking time value, and the blanking time stage is arranged to start generating the blanking time value upon a load current exceeding a predefined set current, the blanking time stage is further arranged to modulate the blanking time value based on a magnitude in which the load current exceeds the predefined set current.