DC Overcurrent Protection Using Electromagnetic Switch-Off
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Solution Overview
Problem
Conventional DC overcurrent protection devices are prone to false triggering or failure due to electromagnetic interference, consume permanent power, and have a high failure rate, making them insufficiently quick in responding to overcurrent conditions.
Innovation Solution
A DC overcurrent protection device utilizing an ignition-current-controlled irreversible high-current disconnection element, an overcurrent detection unit, and control contacts that are electrically connected via an electromagnetic force caused by overcurrent, eliminating the need for continuous power and reducing the complexity and failure rate by using a simple structure that only draws energy from the high-current path during overcurrent events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fuse is used for overcurrent protection, then the device structure is simple, but the response time is too slow to protect components against overload
Solution Approach 1:
The patent replaces the thermal-mechanical operation of conventional fuses with an electromagnetic field-based detection system. The overcurrent detection unit uses electromagnetic forces to actuate control contacts that trigger a pyrotechnical switch-off element, eliminating the slow thermal response mechanism while maintaining structural simplicity.
2Speed
If a pyrotechnical switch-off element with ignition electronics is used, then the response speed is improved, but the device complexity and failure rate increase
Solution Approach 1:
The patent extracts and eliminates the complex electronic measurement and evaluation circuitry from the detection unit. Instead of using electronic sensors and processing systems, the invention uses a purely electromagnetic field-based detection mechanism where overcurrent directly generates electromagnetic forces to actuate the control contacts, significantly simplifying the device structure.
Solution Approach 2:
The overcurrent itself serves as the triggering mechanism. The excessive current directly generates the electromagnetic force needed to actuate the control contacts and initiate the shutdown sequence, eliminating the need for separate sensing, processing, and control electronics.
3Reliability
If continuous power is supplied to the detection circuit, then the detection reliability is improved, but the power consumption increases
Solution Approach 1:
The detection unit operates in a passive state during normal conditions and only activates during overcurrent events. The electromagnetic detection mechanism is triggered periodically or event-driven by the actual overcurrent condition rather than requiring continuous power supply for active sensing, thereby minimizing power consumption while maintaining detection reliability.
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 solution provides a robust, fail-safe, and quick response to overcurrent conditions, being insensitive to electromagnetic interference and minimizing power consumption, with a low failure rate and rapid activation.
Implementation Method 1
the control contacts are electrically connected to one another due to an electromagnetic force caused by the overcurrent
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
DC overcurrent protection apparatus (100) which comprises an ignition current-controlled irreversible high-current switch-off element (2), an overcurrent detection unit (1) which is electrically connected in a high-current path (4) in series with the ignition current-controlled irreversible high-current switch-off element (2), and control contacts (11, 11A-11F) for controlling the ignition current-controlled irreversible high-current switch-off element (2), which are arranged such that they can be electrically connected to one another. The overcurrent detection unit (1) is designed such that when an overcurrent with a value equal to or greater than a predetermined current value flows in the high-current path (4), the control contacts (11, 11A-11F), on account of an electromagnetic force which is created by the overcurrent, are electrically connected to one another in such a way that an ignition current (15) is transmitted to the ignition current-controlled irreversible high-current switch-off element (2), so that the ignition current-controlled irreversible high-current switch-off element (2) is switched by control to a switched-off state (16).