PV Input Protection Circuit for DC Polarity Misconnection
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Solution Overview
Problem
In photovoltaic power generation systems, misconnections at the input end, such as inverted or incorrectly connected positive and negative poles of direct current switches, lead to faults like short circuits and overheating, posing safety risks such as explosions and fires.
Innovation Solution
A protection circuit with a misconnection detection unit, mechanical interlocking unit, and switch unit that prevents misconnections by locking the switch in a disconnected state before closure, using electrical parameter detection to ensure correct polarity before connecting loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If direct current switches are disposed in a same combiner box for convenience of installation and maintenance, then ease of operation is improved, but reliability deteriorates due to increased risk of misconnection
Solution Approach 1:
The patent applies preliminary action by detecting the polarity of direct current switches before closing the switch. The detection unit measures the polarity in advance, and only when the polarity is confirmed correct is the switch allowed to close. This prevents misconnection faults before they can occur, resolving the contradiction by maintaining ease of operation while improving reliability through pre-closure verification.
2Device complexity
If misconnection detection is performed after direct current switch closure, then device complexity is reduced, but harmful factors increase due to short circuit and overheating risks
Solution Approach 1:
The patent applies preliminary anti-action by detecting misconnection polarity before the switch closes. The detection unit identifies incorrect polarity connections in advance, and the control unit prevents switch closure when misconnection is detected. This proactive approach eliminates short circuit and overheating risks before they can manifest, resolving the contradiction by keeping the detection system simple while preventing harmful effects.
3Measurement precision
If misconnection detection unit is connected to input end ports, then measurement precision is improved for polarity detection, but device complexity increases
Solution Approach 1:
The patent applies feedback by using the misconnection detection unit to continuously monitor the polarity of direct current switches. The detection unit's output feeds back to the control unit, which automatically opens the switch when misconnection is detected. This feedback mechanism ensures high measurement precision for polarity detection while keeping the overall device complexity manageable through automated control.
Data Source
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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.