Load Control Circuit Detecting System with Thermal Fuse
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Solution Overview
Problem
Existing load control circuits are vulnerable to burn damage or ignition due to undetected faults, particularly when the fault current is below the rated current of the fuse, leading to potential system failures.
Innovation Solution
A detecting system comprising a main fuse, a switching element, a thermal fuse attached to the switching element, and a controller that monitors the thermal fuse's state to generate a fault signal and interrupt power supply when the thermal fuse opens, effectively detecting micro short circuits that the main fuse cannot detect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only a main fuse is used for protection, then the device complexity is low, but the reliability is insufficient because faults below the fuse's rated current cannot be detected
Solution Approach 1:
The protection function is segmented into two levels: the main fuse handles overcurrent protection above its rated current, while the thermal fuse specifically detects micro-short circuits below the main fuse's rated current. This segmentation allows each component to specialize in a specific protection range, improving overall reliability without requiring complete redesign of the protection system.
Solution Approach 2:
The thermal fuse acts as an intermediary detection element between the switching element and the controller. It mediates the detection of abnormal heat generation caused by micro-short circuits, converting thermal effects into an electrical signal that the controller can recognize and respond to, thereby enabling detection capabilities that neither the main fuse alone nor the controller could achieve independently.
2Reliability
If a thermal fuse is added to detect micro short circuits, then the reliability improves, but the device complexity increases
Solution Approach 1:
The thermal fuse is merged with the switching element by attaching it directly to the switching element's surface. This spatial merging allows the thermal fuse to directly sense the temperature of the switching element without requiring separate mounting structures or additional thermal coupling components, thereby adding detection capability while minimizing the increase in overall device complexity.
Solution Approach 2:
The thermal fuse utilizes the inherent thermal field generated by the switching element during normal operation. Instead of requiring an external heat source or additional energy input, the thermal fuse passively detects abnormal temperature rises caused by micro-short circuits, allowing the system to self-diagnose faults using the thermal energy already present in the operating circuit.
3Measurement precision
If the thermal fuse is attached to the switching element surface, then the detection precision improves, but the manufacturing precision requirements increase
Solution Approach 1:
The thermal fuse is designed with a melting temperature parameter that corresponds to the maximum safe operating temperature of the switching element. By selecting a thermal fuse with an appropriate temperature rating, the system achieves reliable detection of abnormal temperature rises without requiring extremely precise attachment positioning, as the thermal conduction path naturally provides sufficient thermal coupling over the attachment area.
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
The system enhances safety by detecting and interrupting power to prevent secondary accidents and protect the load control circuit from faults that would otherwise go undetected by the main fuse.
Implementation Method 1
a thermal fuse attached to a surface of the switching element and configured to open when a temperature of the switching element exceeds a preset temperature
Implementation Method 2
The thermal fuse may be attached to the surface of the switching element by a heat transfer adhesive material.
Data Source
AI summary
A detecting system for a load control circuit includes: a main fuse connected on a main current path between a power supply and a load that receives power supplied from the power supply; a switching element connected on the main current path between the main fuse and the load; a thermal fuse attached to a surface of the switching element and configured to open when a temperature of the switching element exceeds a preset temperature; a controller configured to control the switching element to be turned on/off, detect an open state of the thermal fuse, and generate a fault signal; and a system controller configured to interrupt the power supplied from the power supply when the fault signal is received from the controller.