Dynamic Overcurrent Limiting for Start-Up and Hiccup Protection
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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, initiating hiccup driving when the first overcurrent limit is reached, with separate limit values and rates for normal and hiccup operation phases to manage peak currents and ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed overcurrent limit value is used to ensure safety, then overheating is prevented, but instantaneous current at start-up cannot be secured
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 normal operation and a second overcurrent limit value (lower) for hiccup operation, allowing the system to adapt to different operational phases and resolve the contradiction between safety and start-up performance.
Solution Approach 2:
The patent changes the parameter of overcurrent limit value based on operational state. By detecting overcurrent conditions and transitioning between different limit values (first limit value during normal operation, second limit value during hiccup operation), the system achieves both safety protection and adequate start-up current capability.
2Device complexity
If a fixed rate of rise is used for output current, then circuit simplicity is maintained, but peak currents cannot be effectively managed
Solution Approach 1:
The rate of rise of output current is changed from a fixed parameter to a dynamic parameter. The circuit employs a first rate of rise for normal operation and a second rate of rise for hiccup operation, enabling effective management of peak currents while maintaining reasonable circuit complexity through the use of standard electronic components.
3Reliability
If overcurrent protection is activated, then safety is ensured, but versatility is reduced due to limited current handling capability
Solution Approach 1:
The patent implements hiccup operation as a periodic action with alternating ON and OFF periods. During the ON period, current flows through the load with the second (lower) overcurrent limit value applied, and during the OFF period, the switch element is turned off. This periodic operation mode maintains safety while enabling the circuit to handle various load types and conditions, thereby preserving versatility.
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.