Reverse-Polarity Relay Circuit for DC Power Input Protection
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Solution Overview
Problem
Existing electronic devices are prone to malfunction due to reverse connection of a direct-current (DC) power source, which can occur when the positive terminal of the power source is connected to the negative terminal of the power input terminal, causing a reverse voltage.
Innovation Solution
A protection device is implemented between the DC power source and the electronic device, utilizing switches, relays, and diodes to ensure proper connection and prevent reverse voltage by disconnecting the power source when a reverse connection is detected, and indicating the correct connection direction through light-emitting diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DC power source is directly connected to the power input terminal of the electronic device, then the electronic device can operate normally, but reverse connection may occur causing malfunction
Solution Approach 1:
The protection device is divided into multiple functional modules: switching elements (first and second switches) for connection control, detecting elements (first and second detecting elements) for polarity detection, and indicating elements (first and second indicating elements) for visual feedback. Each module performs a specific function, allowing the system to detect and respond to reverse connection conditions while maintaining a manageable structural complexity.
Solution Approach 2:
The protection device acts as an intermediary component between the DC power source and the electronic device. It includes switching elements that can disconnect the power source from the electronic device when reverse connection is detected, and indicating elements that provide visual feedback about connection status. This intermediary structure protects the electronic device without requiring modification of the power source or the device itself.
2Reliability
If switching elements are used to disconnect power source during reverse connection, then reverse voltage is blocked, but the device structure becomes more complex
Solution Approach 1:
The protection device combines multiple functions into a single integrated structure: the switching elements are controlled by detecting elements that monitor the same power input terminal, and indicating elements provide visual feedback about the connection status. The first switch connects/disconnects the positive terminal while the second switch handles the negative terminal, with both switches being controlled by a unified detection and indication system, reducing overall system complexity.
Solution Approach 2:
The detecting elements continuously monitor the polarity of the power source before and during connection. When reverse connection is detected, the switching elements are activated to disconnect the power source before reverse voltage can damage the electronic device. The indicating elements provide advance visual warning of the connection status, allowing users to correct improper connections before damage occurs.
3Reliability
If detecting elements continuously monitor power source polarity, then reverse connection is detected promptly, but energy consumption increases
Solution Approach 1:
The detecting elements perform polarity detection at periodic intervals rather than continuously. The system checks the polarity of the power source when connection is made and at regular intervals thereafter, activating the switching elements only when reverse connection is detected. This periodic detection approach maintains reliable reverse connection protection while significantly reducing the energy consumption compared to continuous monitoring.
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
Prevents reverse connection and ensures safe, reliable power supply to the electronic device by blocking reverse voltage and providing visual indication for correct wiring, thereby preventing device malfunction.
Implementation Method 1
indicating the correct connection direction through light-emitting diodes
Data Source
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AI summary
Provided is a protection device of an electronic device to which a first switch includes an input terminal connected to a positive or negative wiring, a first output terminal connected to a first node, and a second output terminal connected to a second node, and a second switch includes an input terminal connected to the positive or negative wiring, a first output terminal connected to a third node, and a second output terminal connected to a fourth node. In a first relay, a relay switch is connected between the first node and a positive input terminal of the electronic device, and an input terminal of a first driver is connected to the first node. In a second relay, a relay switch is connected between a negative input terminal of the electronic device and the third node, and a second driver includes an input terminal connected to an output terminal of the first driver and an output terminal connected to the third node.