Dynamic Overcurrent Threshold Adjustment in Power Supply Circuits
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Solution Overview
Problem
Power supply circuits face issues where low output voltage during activation leads to premature shutdown due to overly conservative overcurrent detection, causing the circuit to fail to operate appropriately while trying to protect itself from overcurrents.
Innovation Solution
A switching control circuit that includes an overload detection circuit, an overcurrent detection circuit, an adjustment circuit, and a control circuit to dynamically adjust the detection thresholds and manage transistor switching to maintain target output voltage levels while preventing overcurrents and overloads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the predetermined current value for overcurrent detection is decreased to improve detection reliability under overload conditions, then the overcurrent detection becomes more reliable, but the power supply circuit may stop activation due to low output voltage during startup
Solution Approach 1:
The patent applies the dynamics principle by making the predetermined current value dynamic rather than fixed. The control circuit adjusts the predetermined current value based on the output voltage level: when the output voltage is below a threshold during activation, a first (higher) current value is used; when the output voltage reaches the threshold, a second (lower) current value is used. This dynamic adjustment resolves the contradiction by adapting the detection threshold to the operational state, ensuring reliable detection under overload while preventing false shutdown during normal activation.
Solution Approach 2:
The patent applies parameter changes by modifying the predetermined current value parameter based on the output voltage parameter. The control circuit monitors the output voltage and changes the current threshold parameter accordingly - maintaining a higher threshold during low-voltage activation phases and switching to a lower threshold during stable operation phases. This parameter adaptation allows the system to achieve both activation reliability and overcurrent detection accuracy.
2Reliability
If the power supply circuit stops operation to protect from overcurrent, then the circuit is protected from damage, but the productivity and continuous operation capability are reduced
Solution Approach 1:
The patent applies dynamics by implementing a dynamic response strategy rather than a static stop-all approach. The control circuit dynamically evaluates multiple parameters (output voltage, load current, predetermined current value) and selectively stops only the switching transistor when overcurrent is detected, while maintaining other circuit operations. This dynamic selective stopping protects the circuit from damage while preserving continuous operation capability and productivity.
Solution Approach 2:
The patent applies segmentation by dividing the circuit operation into separable components - specifically, stopping only the switching transistor (a discrete component) rather than shutting down the entire power supply circuit. This segmented approach allows the protective function to be isolated to the necessary component while maintaining overall system productivity and continuous operation of non-affected circuit sections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the power supply circuit to operate effectively while protecting itself from overcurrents and overloads by adjusting detection thresholds and managing transistor switching, preventing premature shutdown and ensuring reliable operation.
Implementation Method 1
a transformer including a primary coil provided on a primary side thereof, and a secondary coil provided on a secondary side thereof, and generating an output voltage at a target level on the secondary side
Data Source
AI summary
A switching control circuit for controlling switching of a transistor in a power supply circuit, such that the power supply circuit generates an output voltage at a target level. The switching control circuit includes an overload detection circuit detecting that a load of the power supply circuit is in an overload condition, when a voltage according to the output voltage reaches a predetermined level, an overcurrent detection circuit detecting that a load current is an overcurrent, when a current according to the load current reaches a predetermined value, an adjustment circuit decreasing the predetermined value, when a first time period has elapsed since the load becomes in the overload condition, a drive circuit driving the transistor such that the output voltage reaches the target level, and a control circuit causing the drive circuit to stop driving the transistor, after the load becomes in the overload condition or the load current becomes the overcurrent.