Overcurrent Protection Circuit With Dynamic Current Limit Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing overcurrent protection circuits in switch devices fail to effectively combine instantaneous current securing at start-up with safety designs for output limiting, leading to potential overheating and reduced versatility due to fixed overcurrent limit values and rates of rise.
Innovation Solution
An overcurrent protection circuit that dynamically adjusts the overcurrent limit value and rate of rise of the output current, reducing the limit value and rate of rise upon detection of an overcurrent, and implements hiccup driving to manage peak currents, allowing for safer operation and reduced peak current impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed overcurrent limit value is used to ensure safety during output limiting, then safety is improved, but the ability to secure instantaneous current at start-up deteriorates
Solution Approach 1:
The overcurrent limit value is changed from a fixed parameter to a dynamic parameter that varies with operating conditions. The circuit switches between a first overcurrent limit value (higher) for start-up conditions and a second overcurrent limit value (lower) for normal operation, allowing the system to adapt to different operational phases and resolve the contradiction between safety and instantaneous current capability.
Solution Approach 2:
The patent changes the parameter of overcurrent limit value based on detection of current magnitude and duration. By monitoring whether the current exceeds the limit and how long it persists, the circuit dynamically adjusts the limit value to appropriate levels, enabling both high instantaneous current tolerance during start-up and strict safety limiting during abnormal conditions.
2Device complexity
If a fixed rate of rise is used for output current, then control simplicity is improved, but the ability to handle peak currents safely deteriorates
Solution Approach 1:
The rate of rise of output current is changed from a fixed parameter to a dynamic parameter. The circuit detects when current reaches the overcurrent limit value and responds by adjusting the rate of rise, enabling the system to handle peak currents safely during start-up while preventing dangerous current increases during fault conditions.
3Reliability
If overcurrent protection is implemented to prevent overheating, then reliability is improved, but versatility of the switch device deteriorates
Solution Approach 1:
The overcurrent protection function is segmented into distinct operational modes: a permissive mode during start-up that allows high instantaneous currents, and a protective mode during normal operation that enforces strict current limits. This segmentation allows the device to maintain versatility for different applications while ensuring safety through condition-dependent protection.
Solution Approach 2:
The circuit performs preliminary detection of current magnitude and duration before enforcing protection. By monitoring current conditions in advance and only activating protection when abnormal conditions are confirmed, the device maintains versatility for legitimate high-current applications while preventing overheating through timely protective action.
Data Source
AI summary
Disclosed herein is an overcurrent protection circuit configured to, upon detection of an output current that flows through a switch element reaching a first overcurrent limit value, reduce an overcurrent limit value for the output current from the first overcurrent limit value to a second overcurrent limit value smaller than the first overcurrent limit value.