PV Input Protection Circuit With Misconnection Interlock
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Solution Overview
Problem
In direct current power generation or distribution systems, misconnections at the input end, such as inverted or incorrectly connected positive and negative poles, lead to faults like short circuits, current backflow, overheating, and potential safety hazards like explosions or fires.
Innovation Solution
A protection circuit with a misconnection detection unit and a mechanical interlocking unit that prevents the switch from closing if a misconnection is detected, ensuring the switch remains locked in a disconnected state until the connection is corrected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct current switches of multiple loops are disposed in a same combiner box for convenience of installation and maintenance, then ease of operation is improved, but misconnection faults occur more frequently leading to reduced reliability
Solution Approach 1:
The patent applies preliminary action by performing misconnection detection before the direct current switch is closed. The detection unit checks for correct polarity connection in advance, and only allows the switch to close if the connection is verified as correct. This prevents misconnection faults from occurring in the first place, thereby maintaining high reliability while still allowing multiple switches to be disposed in a single combiner box for ease of installation.
2Device complexity
If misconnection detection is performed after the loop is connected, then device complexity is reduced, but security and reliability are insufficient
Solution Approach 1:
The patent implements preliminary detection before the switch closes and before the loop is fully connected. The detection unit is integrated into the circuit and automatically checks for misconnection before allowing current flow. This preliminary action approach enhances security and reliability without significantly increasing device complexity, as the detection function is built into the existing switch structure.
Solution Approach 2:
The patent replaces manual connection verification with an automated detection unit that uses electrical measurement to identify misconnections. Instead of relying on manual checking or mechanical interlocks, the system uses electrical detection of polarity correctness, which enhances reliability while keeping the device complexity manageable through automated electronic detection.
3Device complexity
If no detection mechanism is implemented, then device complexity is minimized, but short circuits and current backflow cause overheating and safety hazards
Solution Approach 1:
The patent applies preliminary anti-action by detecting potential misconnections before they can cause harmful effects. The detection unit identifies incorrect polarity connections in advance, preventing short circuits, current backflow, and subsequent overheating before they occur. This approach effectively counteracts the harmful factors by eliminating their root cause through prior detection.
Solution Approach 2:
The patent introduces a detection unit as an intermediary between the connection and the switch closing action. This intermediary component verifies the correctness of the connection before allowing the circuit to be activated. The detection unit acts as a mediator that prevents harmful effects by blocking incorrect connections from proceeding to the switching stage, thereby protecting the system without requiring complex protective devices.
Data Source
AI summary
This application discloses a protection circuit for preventing a misconnection at an input end and a photovoltaic power generation system, and relates to the field of power electronics technologies. The protection circuit includes an input end, a misconnection detection unit, a mechanical interlocking unit, and a switch unit. The input end is configured to connect to an output end of a direct current power supply. A first input end of the misconnection detection unit is connected to a first port of the input end, and a second input end of the misconnection detection unit is connected to a second port of the input end. An output end of the misconnection detection unit is coupled to the mechanical interlocking unit. The mechanical interlocking unit is connected to the switch unit. A first end of the switch unit is configured to connect to the input end, and a second end of the switch unit is configured to connect to a next circuit. The misconnection detection unit is configured to: when connection wires of the first port and the second port are incorrect, control the mechanical interlocking unit to keep the first end of the switch unit and the second end of the switch unit in a disconnected state. When positive and negative poles of a power supply connected to the input end are misconnected, the protection circuit can be used to prevent a circuit from being affected by the misconnection.